[no] ldp
config>router
This command enables the context to configure an LDP protocol instance.
When an LDP instance is created, the protocol is enabled (in the no shutdown state). To suspend the LDP protocol, use the shutdown command. Configuration parameters are not affected.
The no form of the command deletes the LDP protocol instance, removing all associated configuration parameters. The LDP instance must first be disabled with the shutdown command before being deleted.
n/a — LDP must be explicitly enabled
[no] aggregate-prefix-match
config>router>ldp
This command enables LDP to use the aggregate prefix match function instead of requiring an exact prefix match.
When this command is enabled and an LSR receives a FEC-label binding from an LDP neighbor for a prefix-address FEC element, FEC1, it installs the binding in the LDP FIB if:
the routing table (RIB) contains an entry that matches FEC1. Matching can either be a longest IP match of the FEC prefix or an exact match.
the advertising LDP neighbor is the next hop to reach FEC1
When the FEC-label binding has been installed in the LDP FIB, LDP programs an NHLFE entry in the egress data path to forward packets to FEC1. LDP also advertises a new FEC-label binding for FEC1 to all its LDP neighbors.
When a new prefix appears in the RIB, LDP checks the LDP FIB to determine if this prefix is a closer match for any of the installed FEC elements. If a closer match is found, this may mean that the LSR used as the next hop changes; if so, the NHLFE entry for that FEC must be changed.
When a prefix is removed from the RIB, LDP checks the LDP FIB for all FEC elements that matched this prefix to determine if another match exists in the routing table. If another match exists, LDP must use it. This may mean that the LSR used as the next hop also changes; if so, the NHLFE entry for that FEC must be changed. If another match does not exist, the LSR removes the FEC binding and sends a label withdraw message to its LDP neighbors.
If the next hop for a routing prefix changes, LDP updates the LDP FIB entry for the FEC elements that matched this prefix. It also updates the NHLFE entry for the FEC elements.
The no form of this command disables the use of the aggregate prefix match function. LDP then only performs an exact prefix match for FEC elements.
no aggregate-prefix-match
prefix-exclude policy-name[policy-name …(up to 5 max)]
no prefix-exclude
config>router>ldp>aggregate-prefix-match
This command specifies the policy name containing the prefixes to be excluded from the aggregate prefix match function. Against each excluded prefix, LDP performs an exact match of a specific FEC element prefix, instead of a longest prefix match of one or more LDP FEC element prefixes, when it receives a FEC-label binding or when a change to the prefix occurs in the routing table.
The no form of this command removes all policies from the configuration; therefore, no prefixes are excluded.
no prefix-exclude
specifies the import route policy name. Allowed values are any string up to 32 characters long composed of printable, 7-bit ASCII characters. If the string contains special characters (such as #, $, spaces), the entire string must be enclosed within double quotes.
egress-statistics
config>router>ldp
This command enters the context to enable egress data path statistics at the ingress LER for this FEC.
n/a
[no] fec-prefix ip-prefix[/mask]
config>router>ldp>egress-statistics
This command configures statistics in the egress data path at the ingress LER or LSR for an LDP FEC. The user must also execute the no shutdown command in this context to enable statistics collection.
The no form of this command disables the statistics in the egress data path and removes the accounting policy association from the LDP FEC.
n/a
the IP prefix and prefix length associated with the prefix FEC
accounting-policy policy-id
no accounting-policy
config>router>ldp>egr-stats>fec-prefix
This command associates an accounting policy with an LDP FEC. Only one accounting policy at a time can be associated with an LDP FEC on a particular node.
An accounting policy must first be configured in the config>log>accounting-policy context before it can be associated; otherwise an error message is generated.
The no form of this command removes the accounting policy association.
no accounting policy
the accounting policy ID
[no] collect-stats
config>router>ldp>egr-stats>fec-prefix
This command enables accounting and statistical data collection.
The collected statistic counters can be retrieved via show and monitor commands or with the SNMPv3 interface. The counters can be saved to an accounting file if the specific statistics collection record is included in the default accounting policy or in a user-defined accounting policy.
When the no form of this command is issued, statistics are still accumulated by the forwarding engine; however, the CPU does not obtain the results and write them to the accounting file. If a subsequent collect-stats command is issued, then the counters written to the accounting file also includes all the traffic that went through while the no collect-stats command was in effect.
no collect-stats
export policy-name[policy-name …(up to 5 max)]
no export
config>router>ldp
This command specifies export route policies that determine which routes are exported to LDP neighbors. Configuring an export policy allows the LSR (Label Switch Router) to advertise addresses other than the system IP address. Policies are configured in the config>router>policy-options context. See the ‟Route Policies” section in the 7705 SAR Router Configuration Guide.
If no export policy is specified, non-LDP routes are not be exported from the routing table manager to LDP, and only LDP-learned routes are exported to LDP neighbors.
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 overrides the previous command. A maximum of five policy names can be specified. The specified names must already be defined.
The no form of the command removes all policies from the configuration.
no export
specifies the export route policy name. Allowed values are any string up to 32 characters long composed of printable, 7-bit ASCII characters. If the string contains special characters (such as #, $, spaces), the entire string must be enclosed within double quotes.
export-tunnel-table policy-name [policy-name...(up to 5 max)]
no export-tunnel-table
config>router>ldp
This command enables exporting of SR tunnels from the TTM into LDP (IGP) for the purpose of stitching an LDP FEC to an SR tunnel for the same destination IPv4 /32 IS-IS prefix.
The no form of the command disables the exporting of SR tunnels to LDP.
no export-tunnel-table
the export-tunnel-table route policy name; must be an existing policy-statement name
fast-reroute [backup-sr-tunnel]
no fast-reroute
config>router>ldp
This command enables LDP Fast Reroute (FRR). LDP FRR provides local protection for an LDP FEC by precalculating and downloading a primary and a backup NHLFE for the FEC to the LDP FIB.
This command is limited to IPv4 /32 prefixes in both LDP and SR.
When LDP FRR is enabled and an LFA backup next hop exists for the FEC prefix in the RTM, or for the longest prefix the FEC prefix matches to when the aggregate-prefix-match command is enabled, LDP programs the data path with both a primary NHLFE and a backup NHLFE for each next hop of the FEC.
The backup NHLFE is enabled for each affected FEC next hop when any of the following events occurs:
an LDP interface goes operationally down or is administratively shut down
an LDP session to a peer goes down because the Hello timer or keepalive timer has expired over an interface
the TCP connection used by a link LDP session to a peer goes down
The tunnel-down-damp-time command, when enabled, does not cause the corresponding timer to be activated for a FEC as long as a backup NHLFE is still available.
Because LDP can detect the loss of a neighbor/next hop independently, it is possible that it can switch to the LFA next hop while the IGP (OSPF or IS-IS) is still using the primary next hop. As well, when the interface for the previous primary next hop is restored, the IGP may reconverge before LDP completes the FEC exchange with its neighbor over that interface. This may cause LDP to deprogram the LFA next hop from the FEC and blackhole traffic. To avoid this situation, IGP-LDP synchronization should be enabled on the LDP interface with the config>router>if>ldp-sync-timer command (see the 7705 SAR Router Configuration Guide, ‟IP Router Command Reference”, for information about configuring the ldp-sync-timer).
The backup-sr-tunnel option allows an SR tunnel to be used as a remote LFA or TI-LFA backup tunnel next hop by an LDP FEC. Before this option can be used, the LDP-to-SR stitching feature must be enabled. See LDP-to-Segment Routing Stitching for IPv4 /32 Prefixes (IS-IS) for more information about this feature.
The no form of this command disables LDP FRR.
no fast-reroute
allows an SR tunnel to be used as a remote LFA or TI-LFA backup tunnel next hop by an LDP FEC
fec-originate ip-address/mask [advertised-label in-label][swap-label out-label] interface interface-name
fec-originate ip-address/mask [advertised-label in-label] next-hop ip-address[swap-label out-label]
fec-originate ip-address/mask [advertised-label in-label] next-hop ip-address[swap-label out-label] interface interface-name
fec-originate ip-address/mask[advertised-label in-label] popno fec-originate ip-address/mask interface interface-name
no fec-originate ip-address/mask next-hop ip-address
no fec-originate ip-address/mask next-hop ip-address interface interface-name
no fec-originate ip-address/mask pop
config>router>ldp
This command adds a FEC to the LDP prefix database with a specific label operation on the node.
Permitted operations are swap to originate a FEC for which the LSR is not egress or pop to originate a FEC for which the LSR is egress.
For a swap operation, an incoming label can be swapped with a label in the range of 16 to 1048575. If a swap-label is not configured, the default value is 3.
A route-table entry is required for a FEC with a pop operation to be advertised. For a FEC with a swap operation, a route-table entry must exist and the user-configured next hop for the swap operation must match one of the next hops in the route-table entry.
The next-hop, advertised-label, and swap-label parameters are optional. If a next-hop is configured but no swap-label is specified, the swap occurs with label 3 (implicit null), then the label is popped and the packet is forwarded to the next hop. If the next-hop and swap-label parameters are configured, a regular swap occurs. If no parameters are specified, a pop and forwarding is performed.
no fec-originate
specifies the IP prefix and mask length
specifies the label advertised to the upstream peer. If not configured, the label that is advertised should be from the label pool. If the configured static label is not available, the IP prefix is not advertised.
the LSR to swap the label. If configured, the LSR should swap the label with the configured out-label. If not configured, the default action is pop if the next-hop parameter is not defined.
the number of labels to send to the peer associated with this FEC
specifies the name of the interface that the label for the originated FEC is swapped to. For an unnumbered interface, this parameter is mandatory because there is no address for the next hop. For a numbered interface, it is optional.
specifies the IP address of the next hop
specifies to pop the label and transmit the packet
[no] graceful-restart
config>router>ldp
This command enables graceful restart helper.
The no form of the command disables graceful restart.
graceful-restart
maximum-recovery-time interval
no maximum-recovery-time
config>router>ldp>graceful-restart
This command configures the local maximum recovery time, which is the time (in seconds) that the sender of the TLV would like the receiver to wait, after detecting the failure of LDP communication with the sender.
The no form of the command returns the default value.
120
specifies the maximum length of recovery time, in seconds
neighbor-liveness-time interval
no neighbor-liveness-time
config>router>ldp>graceful-restart
This command configures the neighbor liveness time, which is the time (in seconds) that the LSR retains its MPLS forwarding state. The time should be long enough to allow the neighboring LSRs to resynchronize all the LSPs in a graceful manner, without creating congestion in the LDP control plane.
The no form of the command returns the default value.
120
specifies the length of time, in seconds
[no] implicit-null-label
config>router>ldp
This command enables the implicit null label option for all LDP FECs for which the router is the eLER.
The implicit null label is signaled by the eLER to the previous-hop LSR during FEC signaling by the LDP control protocol. When the implicit null label is signaled to the LSR, it pops the outer label before sending the MPLS packet to the eLER; this is known as penultimate hop popping.
The no form of the command disables the signaling of the implicit null label.
no implicit-null-label
import policy-name[policy-name …(up to 5 max)]
no import
config>router>ldp
This command specifies import route policies that determine which routes are accepted from LDP neighbors. Policies are configured in the config>router>policy-options context. See the ‟Route Policies” section in the 7705 SAR Router Configuration Guide.
If no import policy is specified, LDP accepts all routes from configured LDP neighbors. Import policies can be used to limit or modify the routes accepted and their corresponding parameters and metrics.
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 import commands are issued, the last command entered overrides the previous command. A maximum of five policy names can be specified. The specified names must already be defined.
The no form of the command removes all policies from the configuration.
no import
specifies the import route policy name. Allowed values are any string up to 32 characters long composed of printable, 7-bit ASCII characters. If the string contains special characters (such as #, $, spaces), the entire string must be enclosed within double quotes.
hello timeoutfactor
no hello
config>router>ldp>if-params>ipv4
config>router>ldp>if-params>ipv6
config>router>ldp>if-params>if>ipv4
config>router>ldp>if-params>if>ipv6
config>router>ldp>targ-session>ipv4
config>router>ldp>targ-session>ipv6
config>router>ldp>targ-session>peer
This command configures the hold time. This is the time interval to wait before declaring a neighbor down. The factor parameter derives the hello interval.
Hold time is local to the system and is sent in the hello messages to the neighbor. Hold time cannot be less than three times the hello interval. The hold time can be configured globally (applies to all LDP interfaces) or per interface. The most specific value is used.
After an LDP session is being set up, the hold time is negotiated to the lower of the two peers. After an operational value is agreed upon, the hello factor is used to derive the value of the hello interval.
The no form of the command:
at the interface-parameters and targeted-session levels, sets the hello timeout and the hello factor to the default values
at the interface level, sets the hello timeout and the hello factor to the value defined under the interface-parameters level
at the peer level, sets the hello timeout and the hello factor to the value defined under the targeted-session level
The default value is dependent upon the CLI context. Table: Hello Timeout Factor Default Values lists the hello timeout factor default values.
Context |
Timeout |
Factor |
|---|---|---|
config>router>ldp>if-params>ipv4 config>router>ldp>if-params>ipv6 |
15 |
3 |
config>router>ldp>if-params>interface>ipv4 config>router>ldp>if-params>interface>ipv6 |
Inherits values from interface-parameters context |
|
config>router>ldp>targ-session>ipv4 config>router>ldp>targ-session>ipv6 |
45 |
3 |
config>router>ldp>targ-session>peer |
Inherits values from targeted-session IPv4 or IPv6 context |
|
configures the time interval, in seconds, that LDP waits before declaring a neighbor down
specifies the number of keepalive messages that should be sent on an idle LDP session in the hello timeout interval
keepalive timeoutfactor
no keepalive
config>router>ldp>if-params>ipv4
config>router>ldp>if-params>ipv6
config>router>ldp>if-params>if>ipv4
config>router>ldp>if-params>if>ipv6
config>router>ldp>targ-session>ipv4
config>router>ldp>targ-session>ipv6
config>router>ldp>targ-session>peer
This command configures the time interval, in seconds, that LDP waits before tearing down the session. The factor parameter derives the keepalive interval.
If no LDP messages are exchanged for the configured time interval, the LDP session is torn down. Keepalive timeout is usually three times the keepalive interval. To maintain the session permanently, regardless of the activity, set the value to zero.
After an LDP session is set up, the keepalive timeout is negotiated to the lower of the two peers. After an operational value is agreed upon, the keepalive factor is used to derive the value of the keepalive interval.
The no form of the command:
at the IPv4, IPv6, and targeted-session levels, sets the keepalive timeout and the keepalive factor to the default value
at the IPv4 or IPv6 interface level, sets the keepalive timeout and the keepalive factor to the value defined under the corresponding interface-parameters level
at the peer level, sets the keepalive timeout and the keepalive factor to the value defined under the targeted-session level
The default value is dependent upon the CLI context. Table: Keepalive Timeout Factor Default Values lists the keepalive timeout factor default values.
Context |
Timeout |
Factor |
|---|---|---|
config>router>ldp>if-params>ipv4 config>router>ldp>if-params>ipv6 |
30 |
3 |
config>router>ldp>if-params>interface>ipv4 config>router>ldp>if-params>interface>ipv6 |
Inherits values from interface-parameters context |
|
config>router>ldp>targ-session>ipv4 config>router>ldp>targ-session>ipv6 |
40 |
4 |
config>router>ldp>targ-session>peer |
Inherits values from targeted-session IPv4 or IPv6 context |
|
configures the time interval, expressed in seconds, that LDP waits before tearing down the session
specifies the number of keepalive messages, expressed as a decimal integer, that should be sent on an idle LDP session in the keepalive timeout interval
[no] legacy-ipv4-lsr-interop
config>router>ldp
This command allows interoperability with third-party legacy IPv4 LSR implementations that do not comply with RFC 5036 with respect to the processing of Hello TLVs with the U-bit set.
The command is a global LDP configuration that disables the Nokia proprietary Interface Info TLV (0x3E05) in the Hello message sent to the peer. Disabling this Hello TLV also results in the non-generation of the Nokia proprietary Hello Adjacency Status TLV (0x3E06) because the Interface Info TLV is not sent.
In addition, this command disables the RFC 7552 standard dual-stack capability TLV (0x701) and the Nokia proprietary Adjacency capability TLV (0x3E07).
[no] mcast-upstream-frr
config>router>ldp
This command enables the mLDP fast upstream switchover feature.
When this command is enabled and LDP is resolving an mLDP FEC received from a downstream LSR, it checks whether an ECMP next hop or an LFA next hop to the root LSR node exists. If LDP finds one, it programs a primary ILM on the interface corresponding to the primary next hop and a backup ILM on the interface corresponding to the ECMP or LFA next hop. Then, LDP sends the corresponding labels to both upstream LSR nodes. Under normal operation, the primary ILM accepts packets while the backup ILM drops them. If the interface or the upstream LSR of the primary ILM goes down, causing the LDP session to go down, the backup ILM starts accepting packets.
To make use of the ECMP next hop, the user must configure the ecmp value in the system to at least ‟2”, using the following command:
config>router>ecmp
To make use of the LFA next hop, the user must enable LFA using the following commands (as needed):
config>router>isis>loopfree-alternates
config>router>ospf>loopfree-alternates
Enabling the IP FRR or LDP FRR feature is not strictly required because LDP only needs to know the location of the alternate next hop to the root LSR so it can send the Label Mapping message to program the backup ILM at the initial signaling of the tree. Therefore, enabling the LFA option is sufficient. However, if unicast IP and LDP prefixes need to be protected, then these features and the mLDP fast upstream switchover can be enabled concurrently.
The mLDP FRR fast switchover relies on the fast detection of a loss of an LDP session to the upstream peer to which the primary ILM label had been advertised. It is strongly recommended that the following be performed:
Enable BFD on all LDP interfaces to upstream LSR nodes. When BFD detects the loss of the last adjacency to the upstream LSR, it immediately brings down the LDP session, which causes the CSM to activate the backup ILM.
If there is a concurrent T-LDP adjacency to the same upstream LSR node, enable BFD on the T-LDP peer in addition to enabling it on the interface.
Enable the ldp-sync-timer option on all interfaces to the upstream LSR nodes. If an LDP session to the upstream LSR to which the primary ILM is resolved goes down for any reason other than a failure of the interface or of the upstream LSR, routing and LDP goes out of synchronization. This means that the backup ILM remains activated until the next time SPF is run by IGP. By enabling the IGP-LDP synchronization feature, the advertised link metric is changed to the maximum value as soon as the LDP session goes down. This, in turn, triggers an SPF, and LDP downloads a new set of primary and backup ILMs.
The no form of this command disables fast upstream switchover for mLDP FECs.
no mcast-upstream-frr
mp-mbb-time interval
no mp-mbb-time
config>router>ldp
This command configures the maximum time a point-to-multipoint transit or bud node must wait before switching over to the new path if the new node does not send an MBB TLV to inform the transit or bud node of the availability of the data plane.
The no form of the command sets the wait time to the default.
3 s
specifies the MP MBB wait time
tunnel-down-damp-time seconds
no tunnel-down-damp-time
config>router>ldp
This command specifies the time interval, in seconds, that LDP waits before posting a tunnel down event to the Tunnel Table Manager (TTM).
When LDP can no longer resolve a FEC and deactivates it, it deprograms the NHLFE in the data path; however, it delays deleting the LDP tunnel entry in the TTM until the tunnel-down-damp-time timer expires. This means that users of the LDP tunnel, such as SDPs (for all services) and BGP (for Layer 3 VPNs), is not be notified immediately. Traffic is still blackholed because the NHLFE has been deprogrammed.
If the FEC gets resolved before the tunnel-down-damp-time timer expires, LDP programs the IOM with the new NHLFE and posts a tunnel modify event to the TTM, updating the dampened entry in the TTM with the new NHLFE information.
If the FEC does not get resolved and the tunnel-down-damp-time timer expires, LDP posts a tunnel down event to the TTM, which deletes the LDP tunnel.
The no form of the command resets the damp timer value back to the default value of 3. If the timer value is set to 0, tunnel down events are not dampened but are reported immediately.
3
the time interval that LDP waits before posting a tunnel down event to the TTM