This command administratively disables the entity. When disabled, an entity does not change, reset, or remove any configuration settings or statistics. Many entities must be explicitly enabled using the no shutdown command.
The operational state of the entity is disabled as well as the operational state of any entities contained within. Many objects must be shut down before they can be deleted.
Unlike other commands and parameters where the default state is not indicated in the configuration file, shutdown and no shutdown are always indicated in system-generated configuration files.
The no form of the command puts an entity into the administratively enabled state.
IS-IS Global - the IS-IS protocol is created in the no shutdown state
IS-IS Interface - when an IP interface is configured as an IS-IS interface, IS-IS on the interface is in the no shutdown state by default
This command activates an IS-IS instance on the router and enables access to the context to define IS-IS parameters.
Instance 0, the base instance, is enabled when the isis command is run without specifying an isis-instance. Multiple IS-IS instances are enabled by including an isis-instance value.
The no form of the command deletes the IS-IS instance and removes all configuration parameters.
no isis
This command enables advertisement of a router’s capabilities to its neighbors for informational and troubleshooting purposes. A TLV as defined in RFC 4971 advertises the TE Node Capability Descriptor capability.
The parameters (area and as) control the scope of the capability advertisements.
The no form of this command disables this capability.
no advertise-router-capability
This command enables the forwarding adjacency feature. With this feature, IS-IS advertises an RSVP-TE LSP as a link so that other routers in the network can include it in their SPF calculations. The RSVP-TE LSP is advertised as an unnumbered point-to-point link and the link-state PDU (LSP) has no traffic engineering opaque sub-TLVs as per RFC 3906.
The forwarding adjacency feature can be enabled independently from the IGP shortcut feature (rsvp-shortcut). If both features are enabled for a given IS-IS instance, the forwarding adjacency feature takes precedence.
When this feature is enabled, each node advertises a point-to-point unnumbered link for each best-metric tunnel to the router ID of any endpoint node. The node does not include the tunnels as IGP shortcuts in the SPF calculation directly. Instead, when the LSP advertising the corresponding point-to-point unnumbered link is installed in the local routing database, the node performs an SPF calculation using the link like any other link LSP.
The link bidirectional check requires that a regular link or tunnel link exists in the reverse direction for the tunnel to be used in the SPF calculation.
An RSVP-TE LSP can be excluded from being used as a forwarding adjacency with the config>router>mpls>lsp>no igp-shortcut command.
The no form of this command disables forwarding adjacency and therefore disables the advertisement of RSVP-TE LSPs into IS-IS.
no advertise-tunnel-link
This command configures the area ID portion of the Network Service Access Point (NSAP) address, which identifies a point of connection to the network, such as a router interface.
Addresses in the IS-IS protocol are based on the ISO NSAP addresses and Network Entity Titles (NETs), not IP addresses. NET addresses are constructed similarly to NSAPs with the exception that the selector ID is always 00. NET addresses are exchanged in Hello and LSP PDUs. All NET addresses configured on the node are advertised to its neighbors.
Up to three area addresses can be configured.
NSAP addresses are divided into three parts. Only the area ID portion is configurable:
For level 1 interfaces, neighbors can have different area IDs, but they must have at least one area ID (AFI + area) in common. Sharing a common area ID, they become neighbors and area merging between the potentially different areas can occur.
For level 2 interfaces, neighbors can have different area IDs. However, if they have no area IDs in common, they become only level 2 neighbors and only level 2 LSPs are exchanged.
For level 1/2 interfaces, neighbors can have different area IDs. If they have at least one area ID (AFI + area) in common, they become neighbors. In addition to exchanging level 2 LSPs, area merging between potentially different areas can occur.
If multiple area-id commands are entered, the system ID of all subsequent entries must match the system ID of the first area address.
The no form of the command removes the area address.
n/a — no area address is assigned
This command associates an authentication keychain with the IS-IS instance or level. The keychain is a collection of keys used to authenticate IS-IS messages from remote peers. The keychain allows the rollover of authentication keys during the lifetime of a session and also supports stronger authentication algorithms than clear text and MD5.
The keychain must already be defined in the config>system>security>keychain context.
Either the authentication-key command or the auth-keychain command can be used by IS-IS, but both cannot be supported at the same time. If both commands are configured, the auth-keychain configuration will be applied and the authentication-key command will be ignored.
By default, authentication is not enabled.
no auth-keychain
This command sets an authentication check to reject PDUs that do not match the type or key requirements.
The default behavior when authentication is configured is to reject all IS-IS protocol PDUs that have a mismatch in either the authentication type or authentication key.
When no authentication-check is configured, authentication PDUs are generated and IS-IS PDUs are authenticated on receipt. However, although mismatches cause an event to be generated, the mismatches will not be rejected.
authentication-check
This command sets the authentication key used to verify PDUs sent by neighboring routers on the interface. Neighboring routers use passwords to authenticate PDUs sent from an interface. For authentication to work, both the authentication key and the authentication type on a segment must match. The authentication-type command must also be entered.
To configure authentication on the global level, configure this command in the config>router>isis context. When this parameter is configured on the global level, all PDUs are authenticated, including the Hello PDU.
To override the global setting for a specific level, configure the authentication-key command in the config>router>isis>level context. When configured within the specific level, Hello PDUs are not authenticated.
By default, no authentication key is configured.
Either the authentication-key command or the auth-keychain command can be used by IS-IS, but both cannot be supported at the same time. If both commands are configured, the auth-keychain configuration will be applied and the authentication-key command will be ignored.
The no form of the command removes the authentication key.
no authentication-key
This is useful when a user must configure the parameter, but for security purposes, the actual unencrypted key value is not provided.
This command enables either simple password or message-digest authentication in the global IS-IS or IS-IS level context. Both the authentication key and the authentication type on a segment must match. The authentication-key command must also be entered.
Configure the authentication type at the global level in the config>router>isis context. Configure or override the global setting by configuring the authentication type in the config>router>isis>level context.
The no form of the command disables authentication.
no authentication-type
This command enables authentication of individual IS-IS packets of complete sequence number PDUs (CSNPs).
The no form of the command suppresses authentication of CSNP packets.
csnp-authentication
This command enables the population of the extended TE database (TE-DB) with the link-state information from the IS-IS instance.
The extended TE-DB is used as a central point for importing all link-state, link, node, and prefix information from IGP instances on the router and exporting the information to BGP-LS on the router. This information includes the IGP, TE, SID sub-TLV, and adjacency SID sub-TLV.
The no form of this command disables database exportation.
no database-export
The BGP-LS identifier is optional and is only sent in a BGP-LS NLRI if configured in the IGP instance of an IGP domain.
If this IGP instance participates in traffic engineering with RSVP-TE or SR-TE, the traffic-engineering option is not strictly required because enabling the extended TE-DB populates this information automatically. However, it is recommended that the user enable traffic engineering to make the configuration consistent with other routers in the network that do not require enabling of the extended TE-DB.
This command disables the IGP-LDP synchronization feature on all interfaces participating in the OSPF or IS-IS routing protocol. When this command is executed, the IGP immediately advertises the actual value of the link cost for all interfaces that have the IGP-LDP synchronization enabled if the currently advertised cost is different. IGP-LDP synchronization will then be disabled for all interfaces. This command does not delete the interface configuration.
The no form of this command restores the default settings and re-enables IGP-LDP synchronization on all interfaces participating in the OSPF or IS-IS routing protocol and for which the ldp-sync-timer is configured (refer to the 7705 SAR Router Configuration Guide for information on configuring the ldp-sync-timer).
no disable-ldp-sync
This command enables the context for the configuration of entropy label capabilities (ELC) for the routing protocol.
This command configures the ability to override any received entropy label capability advertisements. When enabled, the system assumes that all nodes for an IGP domain are capable of receiving and processing the entropy label on segment routed tunnels. This command can only be configured if entropy-label is enabled via the config>router>isis>segment-routing>entropy-label command.
The no version of this command disables the override. The system assumes entropy label capability for other nodes in the IGP instance if capability advertisements are received.
no override-tunnel-elc
This command associates export route policies to determine which routes are exported from the route table to IS-IS.
If no export policy is specified, non-IS-IS routes are not exported from the routing table manager to IS-IS.
If multiple policy names are specified, the policies are evaluated in the order they are specified. The first policy that matches is applied. If multiple export commands are issued, the last command entered will override the previous command. A maximum of five policy names can be specified.
The no form of the command removes all policies from the configuration.
Refer to the 7705 SAR Router Configuration Guide for information on defining route policies.
n/a — no export route policies specified
The specified names must already be defined.
This command enables authentication of individual IS-IS Hello PDUs.
The no form of the command suppresses authentication of Hello PDUs.
hello-authentication
This command specifies that this level 1 router will ignore the attached (ATT) bit in received level 1 link-state PDUs (LSPs) and therefore will not install the default route to the level 1/2 router that set the ATT bit.
The no form of the command specifies that the router will install the default route to the closest level 1/2 router.
no ignore-attached-bit
This command specifies that the router will ignore LSPs with internal checksum errors rather than purging the LSPs.
The no form of the command specifies that LSPs with internal checksum errors will be purged, which will cause the originator to resend the LSPs.
no ignore-lsp-errors
This command specifies whether the Instance Identifier (IID) TLV is enabled or disabled for this IS-IS instance so an interface can be used in multiple IS-IS instances.
When enabled, each IS-IS instance marks its packets with the IID TLV containing its unique 16-bit IID for the routing domain. You must use a shutdown/no shutdown command sequence on the IS-IS instance to make the change operational.
The no form of the command disables the IID TLV marking of packets.
no iid-tlv-enable
This command enables or disables IPv4 routing on the IS-IS instance.
ipv4-routing
This command enables or disables single topology (native) IPv6 routing on the IS-IS instance. In native mode, IPv6 routing information is exchanged within IS-IS using IS-IS IPv6 TLVs.
no ipv6-routing
This command enables the context to configure IS-IS level 1 or level 2 area attributes.
To reset global and/or interface level parameters to the default, the following commands must be entered independently:
level 1 or level 2
This command configures the preference for IS-IS external routes for the IS-IS level. The preference for internal routes is set with the preference command.
The command configures the preference level for either level 1 or level 2 external routes. The default preferences are listed in Table 63.
A route can be learned by the router from different protocols, in which case, the costs are not comparable. When this occurs, the preference is used to decide which route will be used.
Different protocols should not be configured with the same preference. If this occurs, the tiebreaker is based on the default preferences as listed in Table 63.
Route Type | Preference | Configurable |
Direct attached | 0 | No |
Static routes | 5 | Yes |
OSPF internal | 10 | Yes |
IS-IS level 1 internal | 15 | Yes |
IS-IS level 2 internal | 18 | Yes |
OSPF external | 150 | Yes |
IS-IS level 1 external | 160 | Yes |
IS-IS level 2 external | 165 | Yes |
If multiple routes are learned with an identical preference using the same protocol, the lowest-cost route is used. If multiple routes are learned with an identical preference using the same protocol and the costs (metrics) are equal, the decision of which route to use is determined by the configuration of ECMP in the config>router context. Refer to the 7705 SAR Router Configuration Guide for information on ECMP.
![]() | Note: To configure a preference for static routes, use the config>router>static-route-entry context. Refer to the 7705 SAR Router Configuration Guide for information. |
The no form of the command reverts to the default value.
external-preference 160 — for IS-IS level 1 external routes
external-preference 165 — for IS-IS level 2 external routes
This command instructs IS-IS to exclude a specific interface or all interfaces participating in a specific IS-IS level from the LFA SPF calculation. The LFA SPF calculation can therefore be run only where it is needed.
If an interface is excluded from the LFA SPF in IS-IS, it is excluded in both level 1 and level 2.
no loopfree-alternate-exclude
This command configures the preference for IS-IS level 1 or level 2 internal routes.
A route can be learned by the router from different protocols, in which case, the costs are not comparable. When this occurs, the preference is used to decide which route will be used.
Different protocols should not be configured with the same preference. If this occurs, the tiebreaker is based on the default preferences as listed in Table 63. If multiple routes are learned with an identical preference using the same protocol and the costs (metrics) are equal, the decision of which route to use is determined by the configuration of ECMP in the config>router context. Refer to the 7705 SAR Router Configuration Guide for information on ECMP.
The no form of the command reverts to the default value.
preference 15 — for IS-IS level 1 internal routes
preference 18 — for IS-IS level 2 internal routes
This command enables the exclusive use of wide metrics in the LSPs for the level number. Narrow metrics can have values between 1 and 63. IS-IS can generate two TLVs, one for the adjacency and one for the IP prefix. In order to support traffic engineering, wider metrics are required. When wide metrics are used, a second pair of TLVs are added for the adjacency and the IP prefix.
By default, both sets of TLVs are generated. When wide-metrics-only is configured, IS-IS only generates the pair of TLVs with wide metrics for that level.
The no form of the command reverts to the default value.
no wide-metrics-only
This command configures the routing level for the IS-IS instance.
An IS-IS router and IS-IS interface can operate at level 1, level 2, or both level 1 and level 2.
A level 1 adjacency can be established if there is at least one area address shared by this router and a neighbor. A level 2 adjacency cannot be established over this interface.
A level 1/2 adjacency is created if the neighbor is also configured as a level 1/2 router and has at least one area address in common. A level 2 adjacency is established if there are no common area IDs.
A level 2 adjacency is established if another router is configured as a level 2 or level 1/2 router with interfaces configured as level 1/2 or level 2. Level 1 adjacencies will not established over this interface.
Table 64 lists capability combinations and the potential adjacencies that can be formed.
Global Level | Interface Level | Potential Adjacency |
Level 1/2 | Level 1/2 | Level 1 and/or level 2 |
Level 1/2 | Level 1 | Level 1 only |
Level 1/2 | Level 2 | Level 2 only |
Level 2 | Level 1/2 | Level 2 only |
Level 2 | Level 2 | Level 2 only |
Level 2 | Level 1 | None |
Level 1 | Level 1/2 | Level 1 only |
Level 1 | Level 2 | None |
Level 1 | Level 1 | Level 1 only |
The no form of the command removes the level capability from the configuration.
level-1/2
This command enables Loop-Free Alternate (LFA) computation by SPF for the IS-IS routing protocol.
When this command is enabled, it instructs the IGP SPF to attempt to precompute both a primary next hop and an LFA backup next hop for every learned prefix. When found, the LFA next hop is populated into the routing table along with the primary next hop for the prefix.
The user enables the remote LFA next-hop calculation by the IGP LFA SPF by using the remote-lfa option. When this option is enabled in an IGP instance, SPF performs the additional remote LFA computation that follows the regular LFA next-hop calculation when the latter calculation results in no protection for one or more prefixes that resolve to a particular interface.
Remote LFA extends the protection coverage of LFA-FRR to any topology by automatically computing and establishing or tearing-down shortcut tunnels, also referred to as repair tunnels, to a remote LFA node that puts the packets back into the shortest path without looping them back to the node that forwarded them over the repair tunnel. The remote LFA node is referred to as a PQ node. A repair tunnel can, in theory, be an RSVP-TE LSP, an LDP-in-LDP tunnel, or a segment routing (SR) tunnel. In this command, remote-lfa is restricted to using an SR repair tunnel to the remote LFA node.
The remote LFA algorithm is a per-link LFA SPF calculation and not a per-prefix calculation like the regular LFA algorithm. The remote LFA algorithm provides protection for all destination prefixes that share the protected link by using the neighbor on the other side of the protected link as a proxy for all the destinations.
The Topology-independent LFA (TI-LFA) further improves the protection coverage of a network topology by computing and automatically instantiating a repair tunnel to a Q node that is not in the shortest path from the computing node. The repair tunnel uses the shortest path to the P node and a source-routed path from the P node to the Q node.
The TI-LFA repair tunnel can have a maximum of three labels pushed in addition to the label of the destination node or prefix. The user can set a lower maximum value for the additional FRR labels by configuring the max-sr-frr-labels option. The default value is 2.
The no form of this command disables the LFA computation by the IGP SPF.
no loopfree-alternate
This command excludes from the LFA SPF calculation any prefixes that match a prefix entry in a prefix policy. If a prefix is excluded, it is not included in the LFA SPF calculation, regardless of its priority. Prefix policies are created with the command config>router> policy-options>prefix-list (for information on prefix lists, refer to the 7705 SAR Router Configuration Guide, “Route Policies”).
The default action of the loopfree-alternate-exclude command, when not explicitly specified in the prefix policy, is to “reject”. Therefore, even if the default-action reject statement was not explicitly stated for the prefix policy, a prefix that does not match any entry in the policy will be used in the LFA SPF calculation.
The no form of the command deletes the excluded prefix policy.
no loopfree-alternate-exclude
This command sets the time interval for LSPs originated by the router to be considered valid by other routers in the domain.
Each LSP received is maintained in an LSP database until the LSP lifetime expires, unless the originating router refreshes the LSP. Each router refreshes its LSPs at the half-life of the lsp-lifetime value (by default, every 10 min (600 s)), so that other routers will not age out the LSP.
The no form of the command reverts to the default value.
1200
This command configures the LSP MTU size. If the MTU size is changed from the default value using the CLI or SNMP, IS-IS must be restarted in order for the change to take effect. This can be done by performing a shutdown command and then a no shutdown command in the config>router>isis context.
![]() | Note: If the MTU size is changed from the default value by using the exec command to execute a configuration file with the changed value, IS-IS will automatically bounce before the change takes effect. |
The no form of the command reverts to the default value.
1492
This command enables the submission of routes into the multicast Route Table Manager (RTM) by IS-IS.
The no form of the command disables the submission of routes into the multicast RTM.
no multicast-import ipv4
This command administratively sets the IS-IS router to operate in the overload state for a specific time period, in seconds, or indefinitely.
During normal operation, the router may be forced to enter an overload state due to a lack of resources. When in the overload state, the router is only used if the destination is reachable by the router and will not be used for other transit traffic.
If a time period is specified, the overload state persists for the configured length of time. If no time is specified, the overload state operation is maintained indefinitely.
The overload command can be useful in circumstances where the router is overloaded or used prior to executing a shutdown command to divert traffic around the router.
The no form of the command causes the router to exit the overload state.
no overload
This command configures IS-IS in the overload state upon boot-up until one of the following events occurs:
When the router is in an overload state, the router is used only if there is no other router to reach the destination.
The no overload command does not affect the overload-on-boot function. If the overload state is cleared with the no overload command, the router will still re-enter the overload state after rebooting.
If no timeout is specified, IS-IS will go into the overload state indefinitely after a reboot. After the reboot, the IS-IS status will display a permanent overload state:
This state can be cleared with the no overload command.
If a timeout value is specified, IS-IS will go into the overload state for the configured timeout after a reboot. After the reboot, the IS-IS status will display the remaining time that the system stays in overload:
The overload state can be cleared before the timeout expires with the no overload command.
The no form of the command removes the overload-on-boot functionality from the configuration.
no overload-on-boot
This command enables the use of the Purge Originator Identification (POI) TLV for this IS-IS instance. The POI is added to purges and contains the system ID of the router that generated the purge, which simplifies troubleshooting and determining what caused the purge.The no form of this command removes the POI functionality from the configuration.
no poi-tlv-enable
This command enables authentication of individual IS-IS packets of partial sequence number PDUs (PSNPs).
The no form of the command suppresses authentication of PSNP packets.
psnp-authentication
This command configures the reference bandwidth used to calculate the default costs of interfaces based on their underlying link speed.
The default interface cost is calculated as follows:
cost = reference bandwidth/bandwidth
If the reference bandwidth is configured as 10 Gbytes (10 000 000 000), a 100 Mb/s interface has a default metric of 100. In order for metrics in excess of 63 to be configured, wide metrics must be deployed (see the wide-metrics-only command).
If the reference bandwidth is not configured, all interfaces have a default metric of 10.
The no form of the command resets the reference bandwidth to the default value.
no reference-bandwidth (all interfaces have a metric of 10)
This command enables the use of an RSVP-TE shortcut for resolving IS-IS routes. When the command is enabled, IS-IS includes RSVP-TE LSPs originating on this node and terminating on the router ID of a remote node as direct links with a metric equal to the operational metric provided by MPLS.
The SPF algorithm will always use the IGP metric to build the SPF tree, and the LSP metric value does not update the SPF tree calculation. During the IP reach to determine the reachability of nodes and prefixes, LSPs are overlaid and the LSP metric is used to determine the subset of paths that are of an equal lowest cost to reach a node or a prefix. If the relative-metric option for this LSP is enabled (in the config>router>mpls>lsp>igp-shortcut context), IS-IS will apply the shortest cost between the endpoints of the LSP plus the value of the offset, instead of the LSP operational metric, when calculating the cost of a prefix that is resolved to the LSP.
When a prefix is resolved to a tunnel next hop, the packet is sent labeled with the label stack corresponding to the NHLFE of the RSVP-TE LSP. Any network event that causes an RSVP-TE LSP to go down will trigger a full SPF calculation, which may result in a new route being installed over another RSVP-TE LSP shortcut as a tunnel next hop or over a regular IP next hop.
When the rsvp-shortcut command is enabled, all RSVP-TE LSPs originating on this node are eligible by default as long as the destination address of the LSP, as configured with the config>router>mpls> lsp>to command, corresponds to a router ID of a remote node. A specific LSP can be excluded from being used as a shortcut with the config>router>mpls> lsp>no igp-shortcut command.
If ECMP is enabled on the system and multiple equal-cost paths exist for the route over a set of tunnel next hops (based on the hashing routine supported for IPv4 packets), there are two possibilities:
ECMP is not performed across both the IP and tunnel next hops.
IS-IS can populate the multicast RTM with the prefix IP next hop when both rsvp-shortcut and multicast-import are enabled. The unicast RTM can still use the tunnel next hop for the same prefix.
The forwarding adjacency feature (advertise-tunnel-link) can be enabled independently from the shortcuts feature. If both features are enabled for a given IS-IS instance, the forwarding adjacency feature takes precedence.
The no form of this command disables the resolution of IGP routes using RSVP shortcuts.
no rsvp-shortcut
This command enables the context to configure segment routing parameters within an IGP instance.
Segment routing adds to IS-IS and OSPF routing protocols the ability to perform shortest path routing and source routing using the concept of abstract segment. An abstract segment can represent a local prefix of a node, a specific adjacency of the node (interface or next-hop), a service context, or a specific explicit path over the network. For each segment, the IGP advertises an identifier referred to as the segment ID (SID).
When segment routing is used together with the MPLS data plane, the SID is a standard MPLS label. A router forwarding a packet using segment routing will push one or more MPLS labels.
Segment routing using MPLS labels can be used in both shortest path routing applications and traffic engineering applications. On the 7705 SAR, segment routing implements the shortest path forwarding application.
After segment routing is successfully enabled in the IS-IS or OSPF instance, the router will perform the following operations:
When the user enables segment routing in an IGP instance, the main SPF and LFA SPF are computed normally and the primary next hop and LFA backup next hop for a received prefix are added to the RTM without the label information advertised in the prefix SID sub-TLV.
This command configures a timer to hold the ILM or LTN of an adjacency SID following a failure of the adjacency.
When an adjacency to a neighbor fails, the IGP will withdraw the advertisement of the link TLV information as well as its adjacency SID sub-TLV. However, the ILM or LTN record of the adjacency SID must be kept in the data path to maintain forwarding using the LFA or remote LFA backup for a sufficient length of time to allow the ingress LER and other routers that use this adjacency SID to activate a new path after the IGP converges.
If the adjacency is restored before the timer expires, the timer is aborted as soon as the new ILM or LTN records are updated with the new primary and backup NHLFE information.
The no form of the command removes the adjacency SID hold time.
15
This command, when used with the force-disable keyword, instructs the system to ignore any received IGP advertisements of entropy label capability relating to remote nodes in the network. The command also prevents a user from configuring override-tunnel-elc for the IGP instance.
The no version of this command enables the processing of any received IGP advertisements of entropy label capability. Using the enable keyword has the same effect.
entropy-label enable
This command enables the exporting of LDP tunnels from the TTM to an IGP instance for the purpose of stitching an SR tunnel to an LDP FEC for the same destination IPv4 /32 prefix.
When this command is enabled, the IGP monitors the LDP tunnel entries in the TTM. Whenever an LDP tunnel destination matches a prefix for which IGP received a prefix SID sub-TLV from the mapping server, the IGP instructs the SR module to program the SR ILM and to stitch it to the LDP tunnel endpoint.
The no form of this command disables the exporting of LDP tunnels to the IGP instance.
no export-tunnel-table
This command enables the context to enable the SR mapping server feature for an IS-IS instance.
The mapping server feature allows the configuration and advertisement via IS-IS of the node SID index for IS-IS prefixes of routers that are in the LDP domain. The router that is acting as a mapping server uses a prefix SID sub-TLV within the SID/Label Binding TLV in IS-IS to advertise a node SID index.
The no form of this command deletes the mapping server.
This command configures the SR mapping server database for an IS-IS instance.
The node-sid index can be configured for one prefix or a range of prefixes by specifying the index value or a value range.
Only the first prefix in a consecutive range of prefixes must be entered. If the first prefix has a mask lower than 32, the SID/Label Binding TLV is advertised but the router does not resolve the prefix SIDs; a trap is originated instead.
The set-flags s option indicates to the IS-IS network routers that the flooding of the SID/Label Binding TLV applies to the entire domain. A router that receives the TLV advertisement leaks it between IS-IS levels 1 and 2. If leaked from level 2 to level 1, the D-flag must be set; this prevents the TLV from being leaked back into level 2. The S-flag is not defined by default; if it is not configured, the TLV is not leaked by routers receiving the mapping server advertisement.
The level option specifies the mapping server’s flooding scope for the generated SID/Label Binding TLV using t. The default flooding scope of the mapping server is level 1/2.
The no form of this command deletes the range of node SIDs beginning with the specified index value.
This command configures the prefix SID index range and offset label value for an IGP instance.
The key parameter is the configuration of the prefix SID index range and the offset label value that this IGP instance will use. Because each prefix SID represents a network global IP address, the SID index for a prefix must be unique network-wide. Therefore, all routers in the network are expected to configure and advertise the same prefix SID index range for an IGP instance. However, the label value used by each router to represent this prefix, that is, the label programmed in the ILM, can be local to that router by the use of an offset label, referred to as a start label:
Local Label (Prefix SID) = start-label + {SID index}
The label operation in the network is very similar to LDP when operating in the independent label distribution mode (RFC 5036, LDP Specification), with the difference that the label value used to forward a packet to each downstream router is computed by the upstream router based on the advertised prefix SID index using the above formula.
There are two mutually exclusive modes of operation for the prefix SID range on the router: global mode and per-instance mode.
In global mode, the user configures the global value and the IGP instance assumes that the start label value is the lowest label value in the Segment Routing Global Block (SRGB) and the prefix SID index range size is equal to the range size of the SRGB. When one IGP instance selects the global option for the prefix SID range, all IGP instances on the system must do the same. The user must shut down the segment routing context and disable the prefix-sid-range command in all IGP instances in order to change the SRGB. When the SRGB is changed, the user must re-enable the prefix-sid-range command. The SRGB range change will fail if an already allocated SID index/label goes out of range.
In per-instance mode, the user partitions the SRGB into non-overlapping sub-ranges among the IGP instances. The user configures a subset of the SRGB by specifying the start label value and the prefix SID index range size. All resulting net label values (start-label + index) must be within the SRGB or the configuration will fail. The 7705 SAR checks for overlaps of the resulting net label value range across IGP instances and will strictly enforce no overlapping of these ranges. The user must shut down the segment routing context of an IGP instance in order to change the SID index/label range of that IGP instance using the prefix-sid-range command. A range change will fail if an already allocated SID index/label goes out of range. The user can change the SRGB without shutting down the segment routing context as long as it does not reduce the current per-IGP instance SID index/label range defined with the prefix-sid-range command. Otherwise, the user must shut down the segment routing context of the IGP instance, and disable and re-enable the prefix-sid-range command.
no prefix-sid-range
This command configures the MTU of all SR tunnels within each IGP instance.
The MTU of an SR tunnel populated into the TTM is determined in the same way as the MTU of an IGP tunnel (for example, an LDP LSP) based on the outgoing interface MTU minus the label stack size. Remote LFA can add, at most, one more label to the tunnel for a total of two labels. There is no default value for this command. If the user does not configure an SR tunnel MTU, the MTU, in bytes, is determined by IGP as follows:
SR_Tunnel_MTU = MIN {Cfg_SR_MTU, IGP_Tunnel_MTU – (1 + frr-overhead)× 4}
where:
The SR tunnel MTU is dynamically updated whenever any of the above parameters used in its calculation changes. This includes if the set of the tunnel next hops changes or the user changes the configured SR MTU or interface MTU value.
no tunnel-mtu
This command configures the TTM preference of shortest path SR tunnels created by the IGP instance. This is used for BGP shortcuts, VPRN auto-bind, or BGP transport tunnel when the tunnel binding commands are configured to the any value, which parses the TTM for tunnels in the protocol preference order. The user can choose either the global TTM preference or explicitly list the tunnel types they want to use. If the user lists the tunnel types explicitly, the TTM preference is still used to select one type over the other. In both cases, a fallback to the next preferred tunnel type is performed if the selected type fails. A reversion to a more preferred tunnel type is performed as soon as one is available.
The segment routing module adds to the TTM an SR tunnel entry for each resolved remote node SID prefix and programs the data path having the corresponding LTN with the push operation pointing to the primary and LFA backup NHLFEs.
The default preference for shortest path SR tunnels in the TTM is set lower than LDP tunnels but higher than BGP tunnels to allow controlled migration of customers without disrupting their current deployment when they enable segment routing. The following list shows the value of the default preference for the various tunnel types. This includes the preference of SR tunnels based on shortest path (referred to as SR-ISIS and SR-OSPF).
![]() | Note: The preference of the SR-TE LSP is not configurable and is the second most preferred tunnel type after RSVP-TE. The preference is the same whether the SR-TE LSP was resolved in IS-IS or OSPF. |
The global default TTM preference for the tunnel types is as follows:
The default value for SR-ISIS or SR-OSPF is the same regardless of whether one or more IS-IS or OSPF instances programmed a tunnel for the same prefix. The selection of an SR tunnel in this case is based on the lowest IGP instance ID.
11
This command enables strict checking of address families (IPv4 and IPv6) for IS-IS adjacencies. When enabled, adjacencies will not come up unless both routers have exactly the same address families configured. If there is an existing adjacency with unmatched address families, it will be torn down. By ensuring that adjacencies are only established if both routers have the same address families, this command prevents the blackholing of traffic that may occur when IPv4 and IPv6 topologies are different.
When the command is disabled, both routers only need to have one common address family to establish the adjacency. A BFD session failure for either IPv4 or IPv6 will cause the routes for the other address family to be removed as well.
no strict-adjacency-check
This command creates summary addresses.
no summary-address
This command suppresses the setting of the attached (ATT) bit in level 1 LSPs originated by this level 1/2 router to prevent all level 1 routers in the area from installing a default route to this router.
The no form of the command enables the setting of the ATT bit.
no suppress-attached-bit
This command configures the IS-IS timer values.
This command is used to customize LSP generation throttling. Timers that determine when to generate the first, second, and subsequent LSPs can be controlled with this command. Subsequent LSPs are generated at increasing intervals of the second lsp-wait timer until a maximum value is reached.
![]() | Note: The IS-IS timer granularity is 100 ms. Timer values are rounded down to the nearest supported value; for example, a configured value of 550 ms is internally rounded down to 500 ms. |
lsp-wait 5000
This command defines the maximum interval, in milliseconds, between two consecutive SPF calculations. Timers that determine when to initiate the first, second, and subsequent SPF calculations after a topology change occurs can be controlled with this command.
Subsequent SPF runs (if required) will occur at exponentially increasing intervals of the spf-second-wait interval. For example, if the spf-second-wait interval is 1000, the next SPF will run after 2000 ms, the SPF after that will run after 4000 ms, and so on, until it reaches the spf-wait value. The SPF interval will stay at the spf-wait value until there are no more SPF runs scheduled in that interval. After a full interval without any SPF runs, the SPF interval will drop back to the spf-initial-wait value.
![]() | Note: The IS-IS timer granularity is 100 ms. Timer values are rounded down to the nearest supported value; for example, a configured value of 550 ms is internally rounded down to 500 ms. |
spf-wait 10000
This command enables traffic engineering and determines if IGP shortcuts are required.
The no form of the command disables traffic-engineered route calculations.
no traffic-engineering
This command allows one IGP to import its routes into the multicast RTM (also known as the RPF RTM [Reverse Path Forwarding - Route Table Manager]) while another IGP imports routes only into the unicast RTM. Import policies can redistribute routes from an IGP protocol into the RPF RTM. By default, the IGP routes will not be imported into the RPF RTM, since such an import policy must be explicitly configured.
The no form of the command enables importing IGP routes into the RPF RTM.
no unicast-import-disable ipv4
This command enables the context to configure an IS-IS interface.
When an area is defined, the interfaces belong to that area. Interfaces cannot belong to other areas.
If the interface is a POS channel, the OSI Network Layer Control Protocol (OSINLCP) is enabled when the interface is created and removed when the interface is deleted.
The no form of the command deletes the IS-IS interface configuration for this interface. The shutdown command in the config>router>isis>interface context can be used to disable an interface without removing the configuration for the interface.
no interface
This command enables the use of bidirectional forwarding (BFD) to control IPv4 adjacencies. By enabling BFD on a given IS-IS interface, the state of the interface is tied to the state of the BFD session between the local node and the remote node. The parameters used for BFD are set via the BFD command under the IP interface.
The no form of this command removes BFD from the associated IPv4 adjacency.
no bfd-enable ipv4
This command configures the interval, in seconds, to send complete sequence number PDUs (CSNPs) from the interface. IS-IS must send CSNPs periodically.
The no form of the command reverts to the default value.
csnp-interval 10 – CSN PDUs are sent every 10 s for LAN interfaces
csnp-interval 5 – CSN PDUs are sent every 5 s for point-to-point interfaces
This command associates a Hello authentication keychain with the IS-IS interface or interface level. The keychain is a collection of keys used to authenticate IS-IS messages from remote peers. The keychain allows the rollover of authentication keys during the lifetime of a session and also supports stronger authentication algorithms than clear text and MD5.
The keychain must already be defined in the config>system>security>keychain context.
Either the hello-authentication-key command or the hello-auth-keychain command can be used by IS-IS, but both cannot be supported at the same time. If both commands are configured, the hello-auth-keychain configuration will be applied and the hello-authentication-key command will be ignored.
no hello-auth-keychain
This command configures the authentication key (password) for Hello PDUs. Neighboring routers use the password to verify the authenticity of Hello PDUs sent from this interface. Both the Hello authentication key and the Hello authentication type on a segment must match. The hello-authentication-type command must also be entered.
To configure the Hello authentication key for all levels configured for the interface, use the hello-authentication-key command in the config>router>isis>interface context.
To configure or override the Hello authentication key for a specific level, use the hello-authentication-key command in the config>router>isis>interface>level context.
If both IS-IS authentication and Hello authentication are configured, Hello messages are validated using Hello authentication. If only IS-IS authentication is configured, it will be used to authenticate all IS-IS protocol PDUs, including Hello PDUs.
Either the hello-authentication-key command or the hello-auth-keychain command can be used by IS-IS, but both cannot be supported at the same time. If both commands are configured, the hello-auth-keychain configuration will be applied and the hello-authentication-key command will be ignored.
The no form of the command removes the hello authentication key from the configuration.
no hello-authentication-key
This is useful when a user must configure the parameter, but for security purposes, the actual unencrypted key value is not provided.
This command enables Hello authentication at either the interface or level context. Both the hello authentication key and the hello authentication type on a segment must match. The hello-auth-keychain command must also be entered.
To configure the hello authentication type for all levels configured for the interface, use the hello-authentication-type command in the config>router>isis>interface context.
To configure or override the hello authentication type for a specific level, use the hello-authentication-type command in the config>router>isis>interface>level context.
The no form of the command disables Hello PDU authentication.
no hello-authentication-type
This command configures the interval between IS-IS Hello PDUs issued on the interface at this level. The hello-interval, along with the hello-multiplier, is used to calculate a hold time, which is communicated to a neighbor in a Hello PDU.
![]() | Note: The neighbor hold time is (hello multiplier × hello interval) on non-designated intermediate system broadcast interfaces and point-to-point interfaces and is (hello multiplier × hello interval / 3) on designated intermediate system broadcast interfaces. Hello values can be adjusted for faster convergence, but the hold time should always be > 3 to reduce routing instability. |
The no form of this command reverts to the default value.
3 – for designated intermediate system interfaces
9 – for non-designated intermediate system interfaces and point-to-point interfaces
This command configures a hello multiplier. The hello-multiplier, along with the hello-interval, is used to calculate a hold time, which is communicated to a neighbor in a Hello PDU.
The hold time is the time in which the neighbor expects to receive the next Hello PDU. If the neighbor receives a Hello within this time, the hold time is reset. If the neighbor does not receive a Hello within the hold time, it brings the adjacency down.
![]() | Note: The neighbor hold time is (hello multiplier × hello interval) on non-designated intermediate system broadcast interfaces and point-to-point interfaces and is (hello multiplier × hello interval / 3) on designated intermediate system broadcast interfaces. Hello values can be adjusted for faster convergence, but the hold time should always be > 3 to reduce routing instability. |
The no form of this command reverts to the default value.
3
This command configures the interface type to be either broadcast or point-to-point.
Use this command to set the interface type of an Ethernet link to point-to-point to avoid having to carry the broadcast adjacency maintenance overhead of the Ethernet link, provided the link is used as a point-to-point link.
If the interface type is not known when the interface is added to IS-IS, and the IP interface is subsequently bound (or moved) to a different interface type, this command must be entered manually.
The no form of the command reverts to the default value.
broadcast – if the physical interface is Ethernet or unknown
point-to-point – if the physical interface is T1, E1, or SONET/SDH
This command assigns a node SID index or label value to the prefix representing the primary address of an IPv4 network interface of type loopback. Only a single node SID can be assigned to an interface. The secondary address of an IPv4 interface cannot be assigned a node SID index and does not inherit the SID of the primary IPv4 address.
This command fails if the network interface is not of type loopback or if the interface is defined in an IES or a VPRN context.
Assigning the same SID index or label value to the same interface in two different IGP instances is not allowed within the same node.
The value of the label or index SID is taken from the range configured for this IGP instance. When using the global mode of operation, the segment routing module checks that the same index or label value is not assigned to more than one loopback interface address. When using the per-instance mode of operation, this check is not required because the index, and therefore the label ranges, of IGP instances are not allowed to overlap.
no ipv4-node-sid
This command assigns a node SID index or label value to the prefix representing the primary address of an IPv6 network interface of type loopback. Only a single node SID can be assigned to an IPv6 interface. When an IPv6 interface has multiple global addresses, the primary address is always the first one in the list, as displayed by the interface info command.
This command fails if the network interface is not of type loopback or if the interface is defined in an IES or a VPRN context.
Assigning the same SID index or label value to the same interface in two different IGP instances is not allowed within the same node.
The value of the label or index SID is taken from the range configured for this IGP instance. When using the global mode of operation, the segment routing module checks that the same index or label value is not assigned to more than one loopback interface address. When using the per-instance mode of operation, this check is not required because the index, and therefore the label ranges, of IGP instances are not allowed to overlap.
no ipv6-node-sid
This command applies a route next-hop policy template to an IS-IS interface. When a route next-hop policy template is applied to an interface in IS-IS, it is applied in both level 1 and level 2.
If the interface has been excluded from LFA with the loopfree-alternate-exclude command, the LFA policy has no effect on the interface.
If the route next-hop policy template is applied to a loopback interface or to the system interface, the command will not be rejected, but the policy will have no effect on the interface.
The no form of the command deletes the mapping of a route next-hop policy template to an IS-IS interface.
no lfa-policy-map
This command configures the interval between link-state PDUs (LSPs) sent from this interface. Controlling the time between LSPs ensures that adjacent neighbors are not being bombarded with excessive data.
A value of 0 means that no LSPs are sent from the interface.
The no form of the command reverts to the default value.
100
This command assigns an interface to a mesh group. Mesh groups limit the amount of flooding that occurs when a new or changed LSP is advertised throughout an area.
All routers in a mesh group should be fully meshed. When LSPs need to be flooded, only a single copy is received rather than one copy per neighbor.
To create a mesh group, configure the same mesh group value for each interface that is part of the mesh group. All routers must have the same mesh group value configured for all interfaces that are part of the mesh group.
To prevent an interface from flooding LSPs, the optional blocked parameter can be specified.
![]() | Caution: Configure mesh groups carefully. It is easy to create isolated islands that will not receive updates if other links fail. |
The no form of the command removes the interface from the mesh group.
no mesh-group
This command configures the metric used for the level on this IS-IS interface.
To calculate the lowest cost to reach a given destination, each configured level on each interface must have a cost. The costs for each level on an interface may be different.
If the metric is not configured, the default value of 10 is used unless the reference-bandwidth is configured.
The no form of the command reverts to the default value.
no metric (10)
This command adds the passive attribute to the IS-IS interface, which causes the interface to be advertised as an IS-IS interface without running the IS-IS protocol. Normally, only interface addresses that are configured for IS-IS are advertised as IS-IS interfaces at the level that they are configured.
If the passive mode is enabled, the interface or the interface at the specified level ignores ingress IS-IS protocol PDUs and will not transmit IS-IS protocol PDUs.
The no form of the command removes the passive attribute.
no passive
This command configures the priority of the IS-IS interface that is used in an election of the designated router (DIS) on a multi-access network.
This parameter is only used if the interface is a broadcast type.
The priority is included in Hello PDUs transmitted by the interface on a multi-access network. The router with the highest priority becomes the designated router. The designated router is responsible for sending LSPs about the network and the routers attached to it.
The no form of the command reverts to the default value.
64
This command specifies the interval, in seconds, that IS-IS will wait before retransmitting an unacknowledged LSP to an IS-IS neighbor.
If the retransmit interval expires and no acknowledgment has been received, the LSP will be retransmitted.
The no form of this command reverts to the default interval.
5
This command enables or disables adjacency SID protection by LFA and remote LFA.
LFA and remote LFA Fast Reroute (FRR) protection is enabled for all node SIDs and local adjacency SIDs when the user enables the loopfree-alternate option in IS-IS or OSPF at the LER and LSR. However, there may be applications where the user never wants traffic to divert from the strict hop computed by CSPF for an SR-TE LSP. In this case, the user can disable protection for all adjacency SIDs formed over a particular network IP interface using this command.
The protection state of an adjacency SID is advertised in the B flag of the IS-IS or OSPF Adjacency SID sub-TLV.
sid-protection
![]() | Note: The following command outputs are examples only; actual displays may differ depending on supported functionality and user configuration. |
This command enables the context to display IS-IS information.
This command displays information about IS-IS neighbors. If no parameters are specified, adjacencies for the specified IS-IS instance are displayed. If detail is specified, operational and statistical information is displayed.
To display adjacency information for all IS-IS instances, use the show router isis all context.
The following output is an example of IS-IS adjacency information, and Table 65 describes the fields for both summary and detailed outputs.
Label | Description |
System ID | System ID of the neighbor |
Usage/L. Circ Typ | Level on the interface: L1, L2, or L1/2 |
State | State of the adjacency: up, down, new, one-way, initializing, or rejected |
Hold/Hold Time | Hold time remaining for the adjacency |
Interface | Interface name associated with the neighbor |
MT-ID | Not applicable. The value 0 is always displayed. |
This command displays information about the capabilities for the specified IS-IS instance. If no parameters are specified, capabilities for the specified IS-IS instance are displayed. If level is specified, only information about the configured level is displayed.
To display capabilities information for all IS-IS instances, use the show router isis all context.
The following output is an example of IS-IS capabilities information, and Table 66 describes the fields.
Label | Description |
LSP ID | The LSP ID of the specified system ID or hostname |
Router Cap | The router IP address and capability |
TE Node Cap | The TE node capability |
SR Cap | The segment routing capability |
SRGB Base | The Segment Routing Global Block (SRGB) base index value and range |
SR Alg | The type of SR algorithm used for the specified LSP ID |
Level (n) Capability Count | The capability count for the specified level |
This command displays information about the IS-IS link-state database. If the system ID and LSP ID are not specified, database entries for the specified IS-IS instance are listed.
To display database information for all IS-IS instances, use the show router isis all context.
The following outputs are examples of IS-IS database information:
Label | Description |
LSP ID | LSP IDs are auto-assigned by the originating IS-IS node. The LSP ID consists of three sections: the first 6 bytes are the system ID for that node, followed by a single byte value for the pseudonode generated by that router, followed by a fragment byte that starts at 0. For example, if a router’s system ID is 1800.0000.0029, the first LSP ID is 1800.0000.0029.00-00. If there are too many routes, LSP ID 1800.0000.0029.00-01 is created to contain the excess routes. If the router is the designated router (or designated intermediate system ([DIS]) on a broadcast network, a pseudonode LSP is created. Usually the internal circuit ID is used to determine the ID assigned to the pseudonode. For instance, for circuit 4, an LSP pseudonode with ID 1800.0000.0029.04-00 is created. Note: The 7705 SAR learns hostnames and uses the hostname in place of the system ID. |
Sequence | The sequence number of the LSP that allows other systems to determine if they have received the latest information from the source |
Checksum | The checksum of the entire LSP packet |
Lifetime | Length of time, in seconds, that the LSP remains valid |
Attributes | OV: the overload bit is set |
L1: specifies a level 1 router | |
L2: specifies a level 2 router | |
L1L2: specifies a level 1/2 router | |
ATT: the attachment bit is set; when set, the router can act as a level 2 router and can reach other areas |
Label | Description |
LSP ID | LSP IDs are auto-assigned by the originating IS-IS node. The LSP ID consists of three sections: the first 6 bytes are the system ID for that node, followed by a single byte value for the pseudonode generated by that router, followed by a fragment byte that starts at 0. For example, if a router’s system ID is 1800.0000.0029, the first LSP ID is 1800.0000.0029.00-00. If there are too many routes, LSP ID 1800.0000.0029.00-01 is created to contain the excess routes. If the router is the designated router (or designated intermediate system ([DIS]) on a broadcast network, a pseudonode LSP is created. Usually the internal circuit ID is used to determine the ID assigned to the pseudonode. For instance, for circuit 4, an LSP pseudonode with ID 1800.0000.0029.04-00 is created. The 7705 SAR learns hostnames and uses the hostname in place of the system ID. |
Sequence | The sequence number of the LSP that allows other systems to determine if they have received the latest information from the source |
Checksum | The checksum of the entire LSP packet |
Lifetime | Length of time, in seconds, that the LSP remains valid |
Attributes | OV: the overload bit is set |
L1: specifies a level 1 router | |
L2: specifies a level 2 router | |
L1L2: specifies a level 1/2 router | |
ATT: the attachment bit is set; when set, the router can act as a level 2 router and can reach other areas | |
LSP Count | A sum of all the configured level 1 and level 2 LSPs |
LSP ID | A unique identifier for each LSP, consisting of the system ID, pseudonode ID, and LSP name |
Version | The version protocol ID extension – always set to 1 |
Pkt Type | The PDU type number |
PkT Ver | The version protocol ID extension – always set to 1 |
Max Area | The maximum number of area addresses supported |
Alloc Len | The amount of memory space allocated for the LSP |
SYS ID | The system ID |
SysID Len | The length of the system ID field (0 or 6) |
Used Len | The actual length of the PDU |
Area Address | The area addresses to which the router is connected |
Supp Protocols | The supported data protocols |
IS-Hostname | The name of the router from which the LSP originated |
Virtual Flag | 0: level 1 routers report this octet as 0 to all neighbors |
1: indicates that the path to a neighbor is a level 2 virtual path used to repair an area partition | |
Neighbor | The routers running interfaces to which the router is connected |
Internal Reach | A 32-bit metric A bit is added for the up/down transitions resulting from level 2 to level 1 route leaking |
IP Prefix | The IP addresses that the router knows about by externally originated interfaces |
Metrics | The routing metric used in the IS-IS link-state calculations |
This command displays the hostname database for the specified IS-IS instance.
To display hostname information for all IS-IS instances, use the show router isis all context.
The following output is an example of hostname database information, and Table 69 describes the fields.
Label | Description |
System ID | The system ID mapped to the hostname |
Hostname | The hostname for the specified system ID |
This command displays the details of the IS-IS interface, which can be identified by IP address or IP interface name. If neither is specified, in-service interfaces for the specified IS-IS instance are displayed.
To display interface information for all IS-IS instances, use the show router isis all context.
The following outputs are examples of IS-IS interface information:
Label | Description |
Interface | The interface name |
Level | The interface level: L1, L2, or L1L2 |
CircID | The circuit identifier |
Oper State | Up: the interface is operationally up |
Down: the interface is operationally down | |
L1/L2 Metric | Interface metric for level 1 and level 2, if none are set to 0 |
Label | Description |
Interface | The interface name |
Level Capability | The routing level for the IS-IS routing process |
Oper State | Up: the interface is operationally up |
Down: the interface is operationally down | |
Admin State | Up: the interface is administratively up |
Down: the interface is administratively down | |
Auth Type | The authentication type for the interface |
Circuit Id | The circuit identifier |
Retransmit Int. | The length of time, in seconds, that IS-IS will wait before retransmitting an unacknowledged LSP to an IS-IS neighbor |
Type | The interface type: point-to-point or broadcast |
LSP Pacing Int. | The interval between LSPs sent from this interface |
Mesh Group | Indicates whether a mesh group has been configured |
CSNP Int. | The time, in seconds, that complete sequence number PDUs (CSNPs) are sent from the interface |
LFA NH Template | Indicates whether an LFA next-hop policy template is applied to this interface |
BFD Enabled | Indicates whether BFD is enabled or disabled |
Topology | The network topology (unicast) |
TE Metric | The TE metric configured for this interface. This metric is flooded out in the TE metric sub-TLV in the IS-IS-TE LSPs. Depending on the configuration, either the TE metric value or the native IS-IS metric value is used in CSPF computations. |
TE State | The MPLS interface TE status from the IS-IS standpoint |
Admin Groups | The bitmap inherited from the MPLS interface that identifies the admin groups to which this interface belongs |
Ldp Sync | Specifies whether the IGP-LDP synchronization feature is enabled or disabled on all interfaces participating in the IS-IS routing protocol |
Ldp Sync Wait | The time to wait for the LDP adjacency to come up |
Ldp Timer State | The state of the LDP sync time left on the IS-IS interface |
LDP TM Left | The time left before IS-IS reverts back to advertising normal metrics for this interface |
Route Tag | The route tag for this interface |
LFA | Indicates whether the interface is included in the LFA SPF calculation |
Level | The interface level |
Adjacencies | The number of adjacencies for this interface |
Auth Type | The authentication type for the interface level |
Metric | Indicates whether a metric has been configured for the interface level |
Hello Timer | The interval between IS-IS Hello PDUs issued on the interface at this level |
IPv6-Ucast-Met | Not applicable |
Priority | The priority of the IS-IS interface that is used in an election of the designated router on a multi-access network |
Passive | Indicates if passive mode is enabled or disabled; if enabled, the interface is advertised as an IS-IS interface without running the IS-IS protocol |
SD-offset | Not applicable |
SF-offset | Not applicable |
Hello Mult. | Not applicable |
This command displays IS-IS LFA coverage information for the specified IS-IS instance.
To display LFA coverage information for all IS-IS instances, use the show router isis all context.
The following output is an example of LFA coverage information, and Table 72 describes the fields.
Label | Description |
Topology | The type of network |
Level | The IS-IS level in which LFA is enabled |
Node | The number of nodes in the level on which LFA is enabled |
IPv4 | The number of IPv4 interfaces on the nodes on which LFA is enabled |
IPv6 | The number of IPv6 interfaces on the nodes on which LFA is enabled |
This command displays IS-IS mapping server information.
The following output is an example of mapping server information.
This command displays IS-IS prefix SID information for the specified IS-IS instance.
To display prefix SID information for all IS-IS instances, use the show router isis all context.
The following output is an example of prefix SIDs information, and Table 73 describes the fields.
Label | Description |
Prefix | The IP prefix for the SID |
SID | The segment routing identifier (SID) |
Lvl/Typ | The level and type of SR |
SRMS | Indicates whether the prefix SID is advertised by the SR mapping service: Y (yes) or N (no) |
MT | Not applicable. The value 0 is always displayed. |
AdvRtr | The advertised router name |
Flags | The flags related to the advertised router: R = Re-advertisement N = Node-SID nP = No penultimate hop POP E = Explicit-Null V = Prefix-SID carries a value L = value/index has local significance |
This command displays the routes in the IS-IS routing table for the specified IS-IS instance.
To display route information for all IS-IS instances, use the show router isis all context.
The following outputs are examples of IS-IS route information, and Table 74 describes the fields.
Label | Description |
Prefix (Flags) | The route prefix and mask, and the L/LFA flag (if applicable) |
Metric | The metric of the route |
Lvl/Typ | The level (1 or 2) and the route type (internal or external) |
Ver. | The SPF version that generated the route |
SysID/Hostname | The hostname for the specific system ID |
MT | Not applicable. The value 0 is always displayed. |
NextHop | The system ID of the next hop (or the hostname, if possible) |
AdminTag/SID[F] | The flags related to the SID: R = Re-advertisement N = Node SID nP = No penultimate hop POP E = Explicit null V = Prefix-SID carries a value L = Value/index has local significance |
Alt-Nexthop | The backup next hop |
Alt-Metric | The metric of the backup route |
Alt-Type | The type of backup route LP = Link protection NP = Node protection |
This command displays the last 20 SPF events for the specified IS-IS instance.
To display SPF log information for all IS-IS instances, use the show router isis all context.
The following output is an example of SPF events, and Table 75 describes the fields.
Label | Description |
When | The timestamp when the SPF run started on the system |
Duration | The time (in hundredths of seconds) required to complete the SPF run |
L1 Nodes | The number of level 1 nodes involved in the SPF run |
L2 Nodes | The number of level 2 nodes involved in the SPF run |
Trigger LSP | The LSP that triggered the SPF run |
Event Count | The number of SPF events that triggered the SPF calculation |
Type SPF Type | The SPF type: Reg (regular) or Lfa (Loopfree-Alternate) |
Reason | The reason(s) for the SPF run: ADMINTAGCHANGED: An administrative tag changed DBCHANGED: The LSP database was cleared by an administrator ECMPCHANGED: An ECMP path changed LFACHANGED: The LFS changed LSPCONTENT: The content of an LSP changed LSPEXPIRED: An LSP expired MANUALREQ: An SPF calculation was requested by an administrator NEWADJ: An adjacency changed NEWAREA: An area changed NEWLSP: A new LSP was received NEWMETRIC: A prefix metric changed NEWNLPID: The routed protocols (IPv4 or IPv6) changed NEWPREF: The external route preference changed NEWREACH: A prefix changed RESTART: The graceful restart exited TUNNELCHANGED: An MPLS tunnel changed |
Log Entries | The total number of log entries |
This command displays information about IS-IS traffic statistics for the specified IS-IS instance.
To display statistics information for all IS-IS instances, use the show router isis all context.
The following output is an example of IS-IS statistical information, and Table 76 describes the fields.
Label | Description |
ISIS Instance | The IS-IS instance |
Purge Initiated | The number of times that purges have been initiated |
LSP Regens | The number of LSP regenerations |
SID SRGB errors | The number of SIDs received that are outside of the Segment Routing Global Block (SRGB) label range |
SID dupl errors | The number of duplicate SIDs received from IS-IS nodes in the network |
CSPF Statistics | |
Requests | The number of CSPF requests made to the protocol |
Request Drops | The number of CSPF requests dropped |
Paths Found | The number of responses to CSPF requests for which paths satisfying the constraints were found |
Paths Not Found | The number of responses to CSPF requests for which paths not satisfying the constraints were found |
SPF Statistics | |
SPF Runs | The number of times that SPF calculations have been made |
Last scheduled | The timestamp of the last SPF run |
Partial SPF Runs | The total number of partial SPF runs |
Last scheduled | The timestamp of the last partial SPF run |
LFA Statistics | |
LFA Runs | The total number of incremental LFA SPF runs triggered by new or updated LSPs |
Last scheduled | The timestamp of the last SPF run |
Partial LFA Runs | The total number of partial LFA SPF runs triggered by new or updated LSPs |
RLFA Statistics | |
RLFA Runs | The total number of incremental remote LFA SPF runs triggered by new or updated LSPs |
TI-LFA Statistics | |
TI-LFA Runs | The total number of incremental topology-independent LFA SPF runs triggered by new or updated LSPs |
Other Statistics | |
PDU Type | The PDU (packet) type |
Received | The number of LSPs received by this instance of the protocol |
Processed | The number of LSPs processed by this instance of the protocol |
Dropped | The number of LSPs dropped by this instance of the protocol |
Sent | The number of LSPs sent out by this instance of the protocol |
Retransmitted | The number of LSPs that had to be retransmitted by this instance of the protocol |
This command displays the general status of IS-IS for the specified IS-IS instance.
To display statistics information for all IS-IS instances, use the show router isis all context.
The following output is an example of IS-IS status information, and Table 77 describes the fields.
Label | Description |
ISIS Oper System Id | The operational system ID mapped to the hostname |
ISIS Cfg Router Id | The router ID configured for the router |
ISIS Oper Router Id | The operational router ID |
ASN | The autonomous system (AS) number |
Admin State | Up: IS-IS is administratively up Down: IS-IS is administratively down |
Oper State | Up: IS-IS is operationally up Down: IS-IS is operationally down |
IPv4 Routing | Enabled: IPv4 routing is enabled Disabled: IPv4 routing is disabled |
IPv6 Routing | Enabled: IPv6 routing is enabled Disabled: IPv6 routing is disabled |
Last Enabled | The date and time that IS-IS was last enabled on the router |
Level Capability | The routing level for the IS-IS routing process |
Authentication Check | True: all IS-IS mismatched packets are rejected False: authentication is performed on received IS-IS protocol packets but mismatched packets are not rejected |
Auth Keychain | Enabled: an authentication keychain is enabled Disabled: an authentication keychain is disabled |
Authentication Type | The method of authentication used to verify the authenticity of packets sent by neighboring routers on an IS-IS interface |
CSNP-Authentication | Indicates whether authentication of CSNP packets is enabled |
HELLO-Authentication | Indicates whether authentication of Hello packets is enabled |
PSNP Authentication | Indicates whether authentication of PSNP packets is enabled |
Traffic Engineering | Enabled: TE is enabled for the router Disabled: TE is disabled; TE metrics are not generated and are ignored when received by this node |
Overload-on-Boot Tim | The length of time that IS-IS is in the overload state upon boot-up |
LSP Lifetime | The length of time that the LSPs originated by the router are to be considered valid by other routers in the domain |
LSP Wait | The length of time that the router will generate the first, second, and subsequent LSPs |
LSP MTU Size | The MTU size for LSPs (configured and operational) |
L1 LSP MTU Size | The MTU size for level 1 LSPs (derived from the LSP MTU size) |
L2 LSP MTU Size | The MTU size for level 2 LSPs (derived from the LSP MTU size) |
Adjacency Check | Type of adjacency check – always “loose” |
L1 Auth Keychain | Enabled: an authentication keychain is enabled on the level 1 router Disabled: an authentication keychain is disabled on the level 1 router |
L1 Auth Type | The method of authentication used to verify the authenticity of packets sent by neighboring routers to an IS-IS level 1 router |
L1 CSNP-Authentication | Indicates whether authentication of CSNP packets is enabled on the level 1 router |
L1 HELLO-Authentication | Indicates whether authentication of Hello packets is enabled on the level 1 router |
L1 PSNP Authentication | Indicates whether authentication of PSNP packets is enabled on the level 1 router |
L1 Preference | The preference level for level 1 internal routes |
L1 Ext. Preference | The preference level for level 1 external routes |
L1 Wide Metrics | Indicates whether wide metrics are enabled or disabled for level 1 routers |
L1 LSDB Overload | Indicates whether link-state database overload is enabled or disabled for level 1 routers |
L1 LSPs | Number of LSPs sent on the level 1 router interface |
L1 Default Metric | The default metric for the level 1 router interface |
L1 IPv6 Def Metric | The default metric for the level 1 router IPv6 interface |
L1 Mcast IPv4 Def Metric | The default metric for the level 1 multicast IPv4 interface |
L1 Mcast IPv6 Def Metric | The default metric for the level 1 multicast IPv6 interface |
L1 Adv Router Cap | The level 1 advertised router capacity |
Last SPF | Date and time that the last SPF calculation was performed |
SPF Wait | Length of time that the first, second, and subsequent SPF calculations are initiated after a topology change occurs |
Area Addresses | The number of area addresses (area IDs) configured for the router |
Total Exp Routes(L1) | Total number of routes exported from the routing table to a level 1 router |
IID TLV | Indicates whether the IID TLV is enabled or disabled for this IS-IS instance |
All-L1-MacAddr | Indicates the MAC address used by this level 1 router interface. For the default (base) IS-IS instance, the MAC address is 01:80:c2:00:00:14. For all other IS-IS instances, the MAC address is 01:00:5e:90:00:02. |
L2 Auth Keychain | Enabled: an authentication keychain is enabled on the level 2 router Disabled: an authentication keychain is disabled on the level 2 router |
L2 Auth Type | The method of authentication used to verify the authenticity of packets sent by neighboring routers to an IS-IS level 2 router |
L2 CSNP-Authentication | Indicates whether authentication of CSNP packets is enabled on the level 2 router |
L2 HELLO-Authentication | Indicates whether authentication of Hello packets is enabled on the level 2 router |
L2 PSNP Authentication | Indicates whether authentication of PSNP packets is enabled on the level 2 router |
L2 Preference | The preference level for level 2 internal routes |
L2 Ext. Preference | The preference level for level 2 external routes |
L2 Wide Metrics | Indicates whether wide metrics are enabled or disabled for level 2 routers |
L2 LSDB Overload | Indicates whether link-state database overload is enabled or disabled for level 2 routers |
L2 LSPs | Number of LSPs sent on the level 2 router interface |
L2 Default Metric | The default metric for the level 2 router interface |
L2 IPv6 Def Metric | The default metric for the level 2 router IPv6 interface |
L2 Mcast IPv4 Def Metric | The default metric for the level 2 multicast IPv4 interface |
L2 Mcast IPv6 Def Metric | The default metric for the level 2 multicast IPv6 interface |
L2 Adv Router Cap | The level 2 advertised router capacity |
Export Policies | Indicates if export policies are applied to the router |
LFA Policies | Lists the defined LFA policies |
Ignore Attached Bit | Indicates whether the ATT bit is ignored on received level 1 LSPs and therefore the level 1 router does not install default routes |
Suppress Attached Bit | Indicates whether the ATT bit is suppressed on originating level 1 LSPs to prevent level 1 routers from installing default routes |
Default Route Tag | n/a |
Rib Prio List High | n/a |
Rib Prio Tag High | n/a |
LDP Sync Admin State | Indicates whether the IGP-LDP synchronization feature is enabled or disabled on all interfaces participating in the IS-IS routing protocol |
LDP-over-RSVP | Indicates whether LDP over RSVP processing is enabled in IS-IS |
RSVP-Shortcut | Indicates whether RSVP-TE shortcuts (IGP shortcuts) are enabled |
Advertise-Tunnel-Link | Indicates whether forwarding adjacencies are enabled |
Export Limit | The maximum number of routes that can be exported into IS-IS from the route table |
Exp Lmt Log Percent | The percentage of the maximum number of routes at which a warning message and SNMP notification is sent |
Total Exp Routes(L2) | Total number of routes exported from the routing table to a level 2 router |
All-L2-MacAddr | Indicates the MAC address used by this level 2 router interface. For the default (base) IS-IS instance, the MAC address is 01:80:c2:00:00:15. For all other IS-IS instances, the MAC address is 01:00:5e:90:00:03. |
Loopfree-Alternate | Indicates whether LFA is enabled |
Remote-LFA | Indicates if remote LFA is enabled or disabled under the loopfree-alternate command |
Max PQ Cost | Indicates the configured maximum PQ cost under the loopfree-alternate command |
TI-LFA | Indicates if TI-LFA is enabled or disabled under the loopfree-alternate command |
Max SR FRR Labels | The maximum number of segment routing FRR labels |
L1 LFA | Indicates whether interfaces in this level are included in the LFA SPF calculation |
L2 LFA | Indicates whether interfaces in this level are included in the LFA SPF calculation |
Advertise Router Cap | Indicates whether router capabilities are enabled |
Hello Padding | Indicates whether hello padding is enabled |
L1 Hello Padding | Indicates whether level 1 hello padding is enabled |
L2 Hello Padding | Indicates whether level 2 hello padding is enabled |
Ignore Lsp Errors | Indicates whether ignoring LSP errors is enabled |
Reference Bandwidth | Indicates configured reference bandwidth for calculating interface metrics |
Ucast Import Disable | Indicates whether ISIS is configured to import its routes into RPF RTM (the multicast routing table) |
Segment Routing | Indicates whether segment routing is enabled |
Mapping Server | Indicates whether server mapping is enabled |
Purge Originator Id | Indicates whether the Purge Originator Identification (POI) TLV is enabled |
Entropy Label | Indicates whether entropy label is enabled |
Override ELC | Indicates whether entropy label capability is enabled for BGP tunnels |
This command displays IS-IS summary addresses for the specified IS-IS instance.
To display statistics information for all IS-IS instances, use the show router isis all context.
The following output is an example of IS-IS summary address information, and Table 78 describes the fields.
Label | Description |
Address | The IP address |
Level | The IS-IS level from which the prefix should be summarized |
Tag | The IS-IS tag (if any) assigned to this summary address |
This command displays IS-IS topology information for the specified IS-IS instance.
To display statistics information for all IS-IS instances, use the show router isis all context.
The following outputs are examples of IS-IS topology information, and Table 79 describes the fields.
Label | Description |
Node | The IP address |
Interface | The interface name |
Nexthop | The next-hop IP address |
Metric | The route metric for the route |
SNPA | The subnetwork points of attachment (SNPA) where a router is physically attached to a subnetwork |
LFA intf LFA interface | The LFA interface name |
LFA Metric | The route metric for the LFA backup route |
LFA nh LFA nexthop | The LFA next hop |
LFA type | The LFA protection type: link protection or node protection |
This command enables the context to clear IS-IS information.
This command clears and resets the entries from the IS-IS adjacency database.
This command removes the entries from the IS-IS link-state database that contains information about PDUs.
This command re-evaluates the route policies for IS-IS.
This command clears the SPF log.
This command clears and resets all IS-IS statistics.
This command enables the context to debug IS-IS information.
This command enables or disables debugging for IS-IS adjacency.
This command enables or disables debugging for an IS-IS constraint-based shortest path first (CSPF).
This command enables or disables debugging for an IS-IS interface.
This command enables or disables debugging for IS-IS leaks.
This command enables or disables debugging for the IS-IS link-state database.
This command enables or disables debugging for miscellaneous IS-IS events.
This command enables or disables debugging for IS-IS packets.
This command enables or disables debugging for the IS-IS routing table manager.
This command enables or disables debugging for IS-IS SPF calculations.
This command enables the context to monitor IS-IS information.
This command enables monitoring statistics for IS-IS instances.
The following output is an example of statistics information for a router IS-IS instance.