OSPF global commands

Context

config>router

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

This command configures the router ID for OSPF.

The router ID configured in the base instance of OSPF overrides the router ID configured in the config>router context.

The default value for the base instance is inherited from the configuration in the config>router context. When that is not configured the following applies:

• The system uses the system interface address (which is also the loop-back address).

• If a system interface address is not configured, use the last 32 bits of the chassis MAC address.

This is a required command when configuring multiple instances and the instance being configured is not the base instance. When configuring multiple instances of OSPF, there is a risk of loops because networks are advertised by multiple domains configured with multiple interconnections to one another. To avoid this from happening all routers in a domain should be configured with the same domain-id. Each domain (OSPF instance) should be assigned a specific bit value in the 32-bit tag mask.

The default value for non-base instances is 0.0.0.0 and is invalid, in this case the instance of OSPF will not start. When configuring a new router ID, the instance is not automatically restarted with the new router ID.

The next time the instance is initialized, the new router ID is used.

Issue the shutdown and no shutdown commands for the instance for the new router ID to be used, or reboot the entire router

The no form of this command reverts to the default value.

Default

no ospf

Parameters

ospf-instance

Specifies a unique integer that identifies a specific instance of a version of the OSPF protocol running in the router instance specified by the router ID.

Values

0 to 31

Context

config>router

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

Commands in this context configure OSPF to support IPv6.

Before OSPFv3 can be activated on the router, the router ID must be configured. The router ID is derived by one of the following methods:

• defining the value using the config>router>router-id ip-address command

• defining the system interface using the config>router>interface ip-int-name command (used if the router ID is not specified with the config>router>router-id ip-address command)

• inheriting the last 4 bytes of the MAC address

When configuring a new router ID, protocols are not automatically restarted with the new router ID. The next time a protocol is initialized, the new router ID is used. To force the new router ID, issue the shutdown and no shutdown commands for OSPFv3 or restart the entire router.

The no form of this command disables OSPF support for IPv6.

Context

config>router>ospf

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

This command enables the advertisement of router capabilities to its neighbors for informational and troubleshooting purposes. A router information (RI) LSA as defined in RFC 4970 advertises the following capabilities:

• OSPF graceful restart capable: no

• OSPF graceful restart helper: yes, when enabled

• OSPF stub router support: yes

• OSPF traffic engineering support: yes, when enabled

• OSPF point-to-point over LAN: yes

• OSPF experimental TE: no

The link, area, and as keywords control the scope of the capability advertisements.

The no form of this command disables this advertisement capability.

Default

no advertise-router-capability

Parameters

link

Keyword specifying to advertise only over local links and not flood beyond.

area

Keyword specifying to advertise only within the area of origin.

as

Keyword specifying to advertise throughout the entire autonomous system.

Context

config>router>ospf

config>router>ospf3

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

This command configures the router as an Autonomous System Boundary Router (ASBR) if the router is to be used to export routes from the Routing Table Manager (RTM) into this instance of OSPF. When a router is configured as an ASBR, the export policies into this OSPF domain take effect. If no policies are configured, no external routes are redistributed into the OSPF domain.

The no form of this command removes the ASBR status and withdraws the routes redistributed from the RTM into this OSPF instance from the link state database.

When configuring multiple instances of OSPF, there is a risk of loops because networks are advertised by multiple domains configured with multiple interconnections to one another. To avoid loops, all routers in a domain should be configured with the same domain ID. Each domain (OSPF instance) should be assigned a specific bit value in the 32-bit tag mask.

When an external route is originated by an ASBR using an internal OSPF route in a specific domain, the corresponding bit is set in the AS-external LSA. As the route gets redistributed from one domain to another, more bits are set in the tag mask, each corresponding to the OSPF domain the route visited. Route redistribution looping is prevented by checking the corresponding bit as part of the export policy; if the bit corresponding to the announcing OSPF process is already set, the route is not exported there. The following figure shows the checking of the corresponding bit.

Figure: Checking corresponding bit

Domain IDs are incompatible with any other use of normal tags. The domain ID should be configured with a value between 1 and 31 by each router in a specific OSPF domain (OSPF instance).

When an external route is originated by an ASBR using an internal OSPF route in a specific domain, the corresponding bit (1 to 31) is set in the AS-external LSA.

The no form of this command removes the ASBR status and withdraws the routes redistributed from the routing table into OSPF from the link-state database.

Default

no asbr

Parameters

domain-id

Specifies the domain ID.

Values

1 to 31

Default

0

Context

config>router>ospf

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

This command enables OSPF summary and external route calculations in compliance with RFC 1583 and earlier RFCs.

RFC 1583 and earlier RFCs use a different method to calculate summary and external route costs. To avoid routing loops, all routers in an OSPF domain should perform the same calculation method.

Although it would be favorable to require all routers to run a more current compliancy level, this command allows the router to use obsolete methods of calculation.

The no form of this command enables the post-RFC 1583 method of summary and external route calculation.

Default

compatible-rfc1583

Context

config>router>ospf

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

This command disables the IGP-LDP synchronization feature on all interfaces participating in the OSPF routing protocol. When this command is executed, 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. It will disable IGP-LDP synchronization for all interfaces. This command does not delete the interface configuration.

For information about LDP synchronization, see ‟IGP-LDP and static route-LDP Synchronization on the 7210 SAS-K 2F6C4T and 7210 SAS-K 3SFP+ 8C” and the ldp-sync and ldp-sync-timer commands in the 7210 SAS-D, Dxp, K 2F1C2T, K 2F6C4T, K 3SFP+ 8C Router Configuration Guide.

The no form of this command restores the default settings and re-enables IGP-LDP synchronization on all interfaces participating in the OSPF routing protocol and for which the ldp-sync-timer is configured.

Default

no disable-ldp-sync

Context

config>router>ospf

config>router>ospf3

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

This command associates export route policies to determine which routes are exported from the route table to OSPF or OSPFv3. Export polices are only in effect if OSPF or OSPFv3 is configured as an ASBR.

If no export policy is specified, non-OSPF or OSPFv3 routes are not exported from the routing table manager to OSPF or OSPFv3.

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 this command removes all policies from the configuration.

Default

no export

Parameters

policy-name

Specifies the export route policy name (the soecified name must already be defined). Allowed values are any string up to 32 characters composed of printable, 7-bit ASCII characters. If the string contains special characters (such #, $, spaces), the entire string must be enclosed within double quotes.

Context

config>router>ospf

config>router>ospf3

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

This command configures the maximum number of routes (prefixes) that can be exported into OSPF or OSPFv3 from the route table.

The no form of this command removes the parameters from the configuration.

Default

no export-limit

Parameters

number

Specifies the maximum number of routes (prefixes) that can be exported into OSPF or OSPFv3 from the route table.

Values

1 to 4294967295

log percentage

Specifies the percentage of the export-limit, at which a warning log message and SNMP notification would be sent.

Values

1 to 100

Context

config>router>ospf

config>router>ospf3

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

This command configures limits on the number of non-default AS-external LSA entries that can be stored in the link-state database (LSDB) and specifies a wait timer before processing these entries after the limit is exceeded.

The limit value specifies the maximum number of non-default AS-external LSA entries that can be stored in the LSDB. Placing a limit on the non-default AS-external LSAs in the LSDB protects the router from receiving an excessive number of external routes that consume excessive memory or CPU resources. If the number of routes reaches or exceeds the configured limit, the table is in an overflow state. When in an overflow state, the router will not originate any new AS-external LSAs and will withdraws all the self-originated non-default external LSAs.

The seconds value specifies the amount of time to wait after an overflow state before regenerating and processing non-default AS-external LSAs. The waiting period acts like a dampening period preventing the router from continuously running Shortest Path First (SPF) calculations caused by the excessive number of non-default AS-external LSAs.

The external-db-overflow command must be set identically on all routers attached to any regular OSPF or OSPFv3 area. OSPF or OSPFv3 stub areas and not-so-stubby areas (NSSAs) are excluded.

The no form of this command disables limiting the number of non-default AS-external LSA entries.

Default

no external-db-overflow

Parameters

limit

Specifies the maximum number of non-default AS-external LSA entries that can be stored in the LSDB before going into an overflow state expressed as a decimal integer.

Values

1 to 2147483674

interval

Specifies the number of seconds after entering an overflow state before attempting to process non-default AS-external LSAs, expressed as a decimal integer.

Values

0 to 2147483674

Context

config>router>ospf

config>router>ospf3

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

This command configures the preference for OSPF or OSPFv3 external 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 determined by the default preference as defined in the Table: Route preference defaults by route type. If multiple routes are learned with an identical preference using the same protocol, the lowest cost route is used.

The no form of this command reverts to the default value.

Default

150

Parameters

preference

Specifies the preference for external routes expressed as a decimal integer. Defaults for different route types are listed in the following table.

Table: Route preference defaults by route type

Route type	Preference	Configurable
Direct attached	0	No
Static routes	5	Yes
OSPF/ OSPFv3 internal	10	Yes
IS-IS level 1 internal	15	Yes
IS-IS level 2 internal	18	Yes
OSPF/OSPFv3 external	150	Yes
IS-IS level 1 external	160	Yes
IS-IS level 2 external	165	Yes
BGP	170	Yes

Note:

Preference for OSPF or OSPFv3 internal routes is configured with the preference command.

Values

1 to 255

Context

config>router>ospf

config>router>ospf3

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

This command enables graceful-restart for OSPF or OSPFv3. When the control plane of a GR-capable router fails, the neighboring routers (GR helpers) temporarily preserve adjacency information, so packets continue to be forwarded through the failed GR router using the last known routes. If the control plane of the GR router comes back up within the GR timer, the routing protocols reconverges to minimize service interruption.

The no form of this command disables graceful restart and removes all graceful restart configurations in the OSPF or OSPFv3 instance.

Default

no graceful-restart

Context

config>router>ospf>graceful-restart

config>router>ospf3>graceful-restart

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

This command disables the helper support for graceful restart.

When graceful-restart is enabled, the router can be a helper (meaning that the router is helping a neighbor to restart) or be a restarting router or both. The router supports only helper mode. This facilitates the graceful restart of neighbors but will not act as a restarting router.

The no form of this command enables helper support and is the default when graceful-restart is enabled.

Default

helper-disable

Context

config>router>ospf3

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

This command specifies the import route policy for an OSPF3 instance.

The no form of this command removes the policy association with the OSPF3 instance.

Default

no import

Parameters

policy-name

Specifies the export route policy name (the soecified name must already be defined). Allowed values are any string up to 32 characters composed of printable, 7-bit ASCII characters. If the string contains special characters (such #, $, spaces), the entire string must be enclosed within double quotes.

Context

config>router>ospf

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

This command enables Loop-Free Alternate (LFA) computation by SPF for the OSPF routing protocol instance.

This command instructs the IGP SPF to precompute both a primary next hop and an LFA 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 remote LFA next hop calculation by the IGP LFA SPF is enabled by using the remote-lfa option. When this option is enabled in an IGP instance, SPF performs the remote LFA additional computation following the regular LFA next-hop calculation when the latter results in no protection for one or more prefixes that are resolved to a specific 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. Doing this 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 LSP, an LDP-in-LDP tunnel, or a segment routing tunnel. Using segment routing repair tunnels is restricted to the remote LFA node.

The remote LFA algorithm is a per-link LFA SPF calculation and is not per-prefix, like the regular LFA calculation. It provides protection to all destination prefixes that share the protected link by using the neighbor on the other side of the protected link as a proxy for those prefixes.

Default

no loopfree-alternate

Parameters

remote-lfa

Keyword to enable the remote LFA next-hop calculation by the IGP LFA SPF.

value

Specifies the maximum IGP cost from the router that is performing the remote LFA calculation to the candidate P or Q node.

Values

0 to 4294967295

Context

config>router>ospf

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

This command excludes from LFA SPF calculation prefixes that match a prefix entry or a tag entry in a prefix policy.

The implementation already allows the user to exclude an interface in IS-IS or OSPF, an OSPF area, or an IS-IS level from the LFA SPF.

If a prefix is excluded from LFA, then it will not be included in LFA calculation regardless of its priority. The prefix tag will, however, be used in the main SPF. Note that prefix tags are defined for the IS-IS protocol but not for the OSPF protocol.

The default action of the loopfree-alternate-exclude command, when not explicitly specified by the user in the prefix policy, is a ‟reject”. Therefore, regardless if the user did or did not explicitly add the statement ‟default-action reject” to the prefix policy, a prefix that did not match any entry in the policy will be accepted into LFA SPF.

The no form of this command deletes the exclude prefix policy.

Parameters

prefix-policy

Specifies the name of the prefix policy. The specified name must have been previously defined. 32 characters maximum.

Context

config>router>ospf

config>router>ospf3

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

This command changes the overload state of the local router so that it appears to be overloaded. When overload is enabled, the router can participate in OSPF or OSPFv3 routing, but is not used for transit traffic. Traffic destined to directly attached interfaces continues to reach the router.

To put the IGP in an overload state, enter a timeout value. The IGP will enter the overload state until the timeout timer expires or a no overload command is executed.

If the overload command is encountered during the execution of an overload-on-boot command, this command takes precedence. This could occur as a result of a saved configuration file where both parameters are saved. When the file is saved by the system the overload-on-boot command is saved after the overload command. However, if overload-on-boot is configured under OSPF or OSPFv3 with no timeout value configured, the router will remain in overload state indefinitely after a reboot.

The no form of this command reverts to the default. When the no overload command is executed, the overload state is terminated regardless of the reason the protocol entered overload state.

Default

no overload

Parameters

timeout seconds

Specifies the number of seconds to reset overloading.

Values

60 to 1800

Default

60

Context

config>router>ospf

config>router>ospf3

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

This command determines whether the OSPF or OSPFv3 stub networks should be advertised with a maximum metric value when the system goes into overload state for any reason. When enabled, the system uses the maximum metric value. When this command is enabled and the router is in overload, all stub interfaces, including loopback and system interfaces, will be advertised at the maximum metric.

Default

no overload-include-stub

Context

config>router>ospf

config>router>ospf3

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

This command configures the IGP upon bootup in the overload state until one of the following events occurs:

• the timeout timer expires.

• a manual override of the current overload state is entered with the no overload command.

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.

The no form of this command removes the overload-on-boot function from the configuration.

Parameters

timeout seconds

Specifies the number of seconds to reset overloading.

Values

60 to 1800

Context

config>router>ospf

config>router>ospf3

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

This command configures the preference for OSPF or OSPFv3 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 preference as defined in Table: Route preference defaults by route type. If multiple routes are learned with an identical preference using the same protocol, the lowest cost route is used.

The no form of this command reverts to the default value.

Default

preference 10

Parameters

preference

Specifies the preference for internal routes, expressed as a decimal integer.

Values

1 to 255

Context

config>router>ospf

config>router>ospf3

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

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

The default reference-bandwidth is 100,000,000 Kb/s or 100 Gb/s, so the default auto-cost metrics for various link speeds are as follows:

• 10 Mb/s link default cost of 10000

• 100 Mb/s link default cost of 1000

• 1 Gb/s link default cost of 100

• 10 Gb/s link default cost of 10

The reference-bandwidth command assigns a default cost to the interface based on the interface speed. To override this default cost on a particular interface, use the metric metric command in the config>router>ospf>area>interface context.

The no form of this command reverts to the default value.

Default

reference-bandwidth 100000000

Parameters

bandwidth-in-kbps

Specifies the reference bandwidth in kilobits per second, expressed as a decimal integer.

Values

1 to 4000000000

Tera-bps

Specifies the reference bandwidth in terabits per second, expressed as a decimal integer.

Values

1 to 4

Giga-bps

Specifies the reference bandwidth in gigabits per second, expressed as a decimal integer.

Values

1 to 4

Mega-bps

Specifies the reference bandwidth in megabits per second, expressed as a decimal integer.

Values

1 to 999

Kilo-bps

Specifies the reference bandwidth in kilobits per second, expressed as a decimal integer.

Values

1 to 999

Context

config>router>ospf

config>router>osp3

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

This command configures the router ID for the OSPF or OSPFv3 instance.

When configuring the router ID in the base instance of OSPF or OSPFv3, it overrides the router ID configured in the config>router context.

The default value for the base instance is inherited from the configuration in the config>router context. If the router ID in the config>router context is not configured, the following applies.

• The system uses the system interface address (which is also the loopback address).

• If a system interface address is not configured, use the last 32 bits of the chassis MAC address.

When configuring a new router ID, the instance is not automatically restarted with the new router ID. The next time the instance is initialized, the new router ID is used.

To force the new router ID to be used, issue the shutdown and no shutdown commands for the instance, or reboot the entire router.

The no form of this command reverts to the default value.

Default

router-id 0.0.0.0

Parameters

ip-address

Specifies a 32-bit unsigned integer uniquely identifying the router in the Autonomous System.

Context

config>router>ospf

config>router>ospf3

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

Commands in this context configure OSPF or OSPFv3 timers. Timers control the delay between receipt of an LSA requiring a Dijkstra (Shortest Path First (SPF)) calculation and the minimum time between successive SPF calculations.

Changing the timers affects CPU utilization and network reconvergence times. Lower values reduce the convergence time but increase CPU utilization. Higher values reduce CPU utilization but increase the reconvergence time.

Context

config>router>ospf>timers

config>router>ospf3>timers

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

This command defines the minimum delay that must pass between receipt of the same LSAs arriving from neighbors.

Nokia recommends that the neighbor configured lsa-generate lsa-second-wait interval is equal or greater than the lsa-arrival timer configured here.

The no form of this command reverts to the default value.

Default

no lsa-arrival

Parameters

lsa-arrival-time

Specifies the timer, in milliseconds. Values entered that do not match this requirement are rejected.

Values

0 to 600000

Context

config>router>ospf>timers

config>router>ospf3>timers

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

This command customizes the throttling of OSPF or OSPFv3 LSA generation. Timers that determine when to generate the first, second, and subsequent LSAs can be controlled with this command. Subsequent LSAs are generated at increasing intervals of the lsa-second-wait timer until a maximum value is reached.

Configuring the lsa-arrival interval to equal or less than the lsa-second-wait interval configured in the lsa-generate command is recommended.

The no form of this command reverts to the default value.

Default

no lsa-generate

Parameters

max-lsa-wait

Specifies the maximum interval, in milliseconds, between two consecutive ocurrences of an LSA being generated

Values

10 to 600000

Default

5000

lsa-initial-wait

Specifies the first waiting period between LSA originates, in milliseconds. When the LSA exceeds the lsa-initial-wait timer value and the topology changes, there is no wait period and the LSA is immediately generated.

When an LSA is generated, the initial wait period commences. If within the specified lsa-initial-wait period and another topology change occurs, the lsa-initial-wait timer applies.

Values

10 to 600000

Default

5000

lsa-second-wait

Specifies the hold time in milliseconds between the first and second LSA generation. The next topology change is subject to this second wait period. With each subsequent topology change, the wait time doubles (this is 2x the previous wait time.). This assumes that each failure occurs within the relevant wait period.

Values

10 to 600000

Default

5000

Context

config>router>ospf>timers

config>router>ospf3>timers

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

This command defines the maximum interval between two consecutive SPF calculations in milliseconds. 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 milliseconds, and then next SPF will run after 4000 milliseconds, 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.

The timer must be entered in increments of 100 milliseconds. Values entered that do not match this requirement will be rejected.

The no form of this command reverts to the default value.

Default

no spf-wait

Parameters

max-spf-wait

Specifies the maximum interval, in milliseconds, between two consecutive SPF calculations.

Values

10 to 120000

Default

1000

spf-initial-wait

Specifies the initial SPF calculation delay, in milliseconds, after a topology change.

Values

10 to 100000

Default

1000

spf-second-wait

Specifies the hold time, in milliseconds, between the first and second SPF calculation.

Values

10 to 100000

Default

1000

Context

config>router>ospf

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

Commands in this context configure segment routing parameters within an IGP instance.

Segment routing adds to OSPF routing protocols the ability to perform shortest path routing and source routing using the concept of the abstract segment. A 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 a 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 pushes one or more MPLS labels.

Segment routing using MPLS labels is used in both shortest path routing applications and traffic engineering applications. This command configures the shortest path forwarding application.

After segment routing is configured in the OSPF instance, the router performs the following operations.

1. Advertises the segment routing capability sub-TLV to routers in all areas and levels of this IGP instance. However, only neighbors with which it established an adjacency will interpret the SID and label range information and use it for calculating the label to swap to or push for a given resolved prefix SID.

2. Advertises the assigned index for each configured node SID in the new prefix SID sub-TLV with the N-flag (node-SID flag) set. The segment routing module then programs the incoming label map (ILM) with a pop operation for each local node SID in the data path.

3. Automatically assigns and advertises an adjacency SID label for each formed adjacency over a network IP interface in the new adjacency SID sub-TLV. The segment routing module programs the ILM with a pop operation (in effect with a swap to an implicit null label operation), for each advertised adjacency SID.

4. Resolves received prefixes, and if a prefix SID sub-TLV exists, the segment routing module programs the ILM with a swap operation and an LTN with a push operation both pointing to the primary/LFA NHLFE. An SR tunnel is also added to the TTM.

When the user enables segment routing in an IGP instance, the main SPF and LFA SPF are computed, 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.

The no form of this command reverts to the default value.

Context

config>router>ospf>segment-routing

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

This command configures the prefix SID index range and offset label value for an IGP instance.

The user must configure the prefix SID index range and the offset label value that this IGP instance uses. Because each prefix SID represents a network global IP address, the SID index for a prefix must be unique in the network. 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, as in the following:

Local Label (Prefix SID) = start-label + {SID index}

The label operation in the network becomes similar to LDP when operating in the independent label distribution mode (RFC 5036), 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 preceding formula.

There are two mutually exclusive modes of operation for the prefix SID range on the router. In the global mode of operation, the user configures the global value and this IGP instance assumes the start label value is the lowest label value in the SRGB and the prefix SID index range size 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 are restricted to do the same. The user must shut down the segment routing context and delete the prefix-sid-range command in all IGP instances to change the SRGB. After the SRGB is changed, the user must re-enter the prefix-sid-range command. The SRGB range change fails if an already allocated SID index or label goes out of range.

In the per-instance mode of operation, the user partitions the SRGB into non-overlapping sub-ranges among the IGP instances. The user therefore 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 fails.

The code checks for overlaps of the resulting net label value range across IGP instances and strictly enforces that these ranges do not overlap. The user must shut down the segment routing context of an IGP instance to change the SID index or label range of that IGP instance using the prefix-sid-range command.

In addition, any range change will fail if an already allocated SID index or label goes out of range. The user can, however, change the SRGB on the fly as long as it does not reduce the current per-IGP instance SID index or label range defined in the prefix-sid-range command. Otherwise, the user must shut down the segment routing context of the IGP instance and delete and reconfigure the prefix-sid-range command.

The no form of this command reverts to the default value.

Default

no prefix-sid-range

Parameters

start-label label-value

Specifies the label offset for the SR label range of this IGP instance.

Values

0 to 524287

max-index index-value

Specifies the maximum value of the prefix SID index range for this IGP instance.

Values

1 to 524287

global

Keyword to enable global operation mode.

Context

config>router>ospf>segment-routing

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

This command configures the maximum transmission unit (MTU) of all SR tunnels within each IGP instance.

The MTU of an SR tunnel populated into the TTM is determined like in the case of an IGP tunnel; for example, LDP LSP, based on the outgoing interface MTU minus the label stack size. Remote LFA can add at least two more labels to the tunnel for a total of three labels. There is no default value. If the user does not configure an SR tunnel MTU, the MTU is determined by IGP.

The MTU of the SR tunnel in bytes is determined as follows:

SR_Tunnel_MTU = MIN {Cfg_SR_MTU, IGP_Tunnel_MTU- (1+ frr-overhead)*4}

Where:

• Cfg_SR_MTU is the MTU configured by the user for all SR tunnels within a specific IGP instance using this command. If no value was configured by the user, the SR tunnel MTU will be determined by the following IGP interface calculation.

• IGP_Tunnel_MTU is the minimum of the IS-IS or OSPF interface MTU among all the ECMP paths or among the primary and LFA backup paths of this SR tunnel.

• frr-overhead is set to 1 if segment-routing and remote-lfa options are enabled in the IGP instance. Otherwise, it is set to 0.

The SR tunnel MTU is dynamically updated whenever any of the preceding parameters used in its calculation changes. This includes when the set of tunnel next hops changes, or the user changes the configured SR MTU or interface MTU value.

The no form of this command reverts to the default value.

Default

no tunnel-mtu

Parameters

bytes

Specifies the size of the MTU in bytes.

Values

512 to 9198

Context

config>router>ospf>segment-routing

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

This command configures the TTM preference of shortest path SR tunnels created by the IGP instance. The TMM preference is used in the case of VPRN auto-bind or BGP transport tunnels when the new tunnel binding commands are configured to the any value, which parses the TTM for tunnels in the protocol preference order. The user can either use the global TTM preference or list the tunnel types they want to use. When they list the tunnel types explicitly, the TTM preference is used to select one type over the other. In both cases, a fallback to the next preferred tunnel type is performed if the selected one fails. Also, a reversion to a more preferred tunnel type is performed as soon as one is available.

The segment routing module adds an SR tunnel entry to the TTM for each resolved remote node SID prefix and programs the datapath with 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 is the setting of the default preference for various tunnel types. This includes the preference of SR tunnels based on the shortest path (referred to as SR-OSPF).

The global default TTM preference for the tunnel types is as follows:

• ROUTE_PREF_RSVP 7

• ROUTE_PREF_SR_TE 8

• ROUTE_PREF_LDP 9

• ROUTE_PREF_OSPF_TTM 10

• ROUTE_PREF_ISIS_TTM 11

• ROUTE_PREF_BGP_TTM 12

• ROUTE_PREF_GRE 255

The default value for SR-OSPF is the same regardless of whether one or more 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.

The no form of this command reverts to the default value.

Default

no tunnel-table-pref

Parameters

preference

Specifies the integer value to represent the preference of OSPF SR tunnels in the TTM.

Values

1 to 255

Default

10

Context

config>router>ospf

Platforms

Supported on all 7210 SAS platforms as described in this document

Description

This command enables traffic engineering route calculations constrained by nodes or links.

Traffic engineering enables the router to perform route calculations constrained by nodes or links. The traffic engineering capabilities of this router are limited to calculations based on link and nodal constraints.

The no form of this command disables traffic-engineered route calculations.

Default

no traffic-engineering