LDP global commands

ldp

Syntax

[no] ldp

Context

config>router

Platforms

Supported on all 7210 SAS platforms as described in this document.

Description

Commands in this context configure LDP parameters. LDP is not enabled by default and must be explicitly enabled (no shutdown).

To suspend the LDP protocol, use the shutdown command. Configuration parameters are not affected.

The no form of this command deletes the LDP protocol instance, removing all associated configuration parameters. The LDP instance must first be disabled using the shutdown command before being deleted.

aggregate-prefix-match

Syntax

[no] aggregate-prefix-match

Context

config>router>ldp

Platforms

Supported on all 7210 SAS platforms as described in this document.

Description

This command enables LDP to use the aggregate prefix match function instead of requiring an exact prefix match.

When this command is enabled, LDP performs the following procedures for all prefixes. When an LSR receives a FEC-label binding from an LDP neighbor for a specific FEC1 element, it installs the binding in the LDP FIB if:

  • it is able to perform a successful longest IP match of the FEC prefix with an entry in the routing table

  • the advertising LDP neighbor is the next hop to reach the FEC prefix

When the FEC-label binding has been installed in the LDP FIB, LDP programs a next-hop label forwarding entry (NHLFE) in the egress datapath 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 routing table, 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, LDP may have to update the NHLFE for this FEC.

When a prefix is removed from the routing table, 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, it updates the NHLFE accordingly. If not, it sends a label withdraw message to its LDP neighbors to remove the binding.

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 for these FEC elements.

The no form of this command disables the use of the aggregate prefix match function and deletes the configuration. LDP then performs only exact prefix matching for FEC elements.

Default

no aggregate-prefix-match

prefix-exclude

Syntax

prefix-exclude policy-name [policy-name...(up to 5 max)]

no prefix-exclude

Context

config>router>ldp>aggregate-prefix-match

Platforms

Supported on all 7210 SAS platforms as described in this document.

Description

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 this prefix occurs in the routing table.

The no form of this command removes all policies from the configuration.

Default

no prefix-exclude

Parameters

policy-name

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 (#, $, spaces, and so on), the entire string must be enclosed within double quotes.

export

Syntax

export policy-name [policy-name … up to 5 max]

no export

Context

config>router>ldp

Platforms

Supported on all 7210 SAS platforms as described in this document.

Description

This command specifies the export route policies that determine which routes are exported to LDP. Policies are configured in the config>router>policy-options context.

If no export policy is specified, non-LDP routes are not exported from the routing table manager to LDP, and LDP-learned routes are exported only to LDP neighbors. The current implementation of the export policy (outbound filtering) can be used only to add FECs for label propagation. The export policy does not control propagation of FECs that an LSR receives from its 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. Specified names must already be defined.

The no form of this command removes all policies from the configuration.

Default

no export

Parameters

policy-name

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

The specified names must already be defined.

fast-reroute

Syntax

fast-reroute

no fast-reroute

Context

config>router>ldp

Platforms

Supported on all 7210 SAS platforms as described in this document.

Description

This command enables LDP Fast-Reroute (FRR). When enabled, LDP uses both the primary next hop and LFA next hop, when available, for resolving the next hop of an LDP FEC against the corresponding prefix in the routing table. This results in LDP programming a primary NHLFE and a backup NHLFE into the forwarding engine for each next hop of a FEC prefix for the purpose of forwarding packets over the LDP 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. In this case, LDP sends a neighbor/next-hop down message to the IOM for each LDP peer it has adjacency with over this interface.

  • An LDP session to a peer goes down because the Hello or keepalive timer has expired over a specific interface. In this case, LDP sends a neighbor/next-hop down message to the IOM for this LDP peer only.

  • The TCP connection used by a link LDP session to a peer goes down because, for example, next-hop tracking of the LDP transport address in RTM brings down the LDP session. In this case, LDP sends a neighbor/next-hop down message to the IOM for this LDP peer only.

  • A BFD session, enabled on a T-LDP session to a peer, times out and causes the link LDP session to the same peer, which uses the same TCP connection as the T-LDP session, to also go down. In this case, LDP sends a neighbor/next-hop down message to the IOM for this LDP peer only.

  • A BFD session enabled on the LDP interface to a directly connected peer times out and brings down the link LDP session to this peer. In this case, LDP sends a neighbor/next-hop down message to the IOM for this LDP peer only. BFD support on LDP interfaces is a recent feature that provides faster tracking of link LDP peers.

The tunnel-down-dump-time option or the label-withdrawal-delay option, 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 will switch to the LFA next hop while IGP is still using the primary next hop. Also, when the interface for the previous primary next hop is restored, 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.

When the SPF computation determines there is more than one primary next hop for a prefix, it does not program an LFA next hop in RTM. The LDP FEC will resolve to the multiple primary next hops that provide the required protection.

The no form of this command disables LDP FRR.

Default

no fast-reroute

fec-originate

Syntax

fec-originate ip-prefix/mask [advertised-label in-label] [swap-label out-label] interface interface-name

fec-originate ip-prefix/mask [advertised-label in-label] next-hop ip-address [swap-label out-label]

fec-originate ip-prefix/mask [advertised-label in-label] next-hop ip-address [swap-label out-label] interface interface-name

fec-originate ip-prefix/mask [advertised-label in-label] pop

no fec-originate ip-prefix/mask interface interface-name

no fec-originate ip-prefix/mask next-hop ip-address

no fec-originate ip-prefix/mask next-hop ip-address interface interface-name

no fec-originate ip-prefix/mask pop

Context

config>router>ldp

Platforms

Supported on all 7210 SAS platforms as described in this document.

Description

This command configures a way to originate a FEC (with a swap action) for which the LSR is not egress, or to originate a FEC (with a pop action) for which the LSR is egress.

Parameters

ip-prefix/mask

Specifies the information for the specified IP prefix and mask length.

Values

<ip-address/mask>

ipv4-prefix - a.b.c.d

ipv4-prefix-le - 0 to 32

ipv6-prefix

x:x:x:x:x:x:x:x (eight 16-bit pieces)

x:x:x:x:x:x:d.d.d.d

x - [0 to FFFF]H

d - [0 to 255]D

ipv6-prefix-le - 0 to 128

ip-address

Specifies the IP address of the next hop of the prefix.

Values

ipv4-address

a.b.c.d

ipv6-address

x:x:x:x:x:x:x:x (eight 16-bit pieces)

x:x:x:x:x:x:d.d.d.d

x - [0 to FFFF]H

d - [0 to 255]D

advertised-label

Keyword to specify the label advertised to the upstream peer. If not configured, the label advertised should be from the label pool. If the configured static label is not available, the IP prefix is not advertised.

out-label

Specifies the LSR to swap the label. If configured, the LSR should swap the label with the configured swap-label. If not configured, the default action is pop if the next-hop parameter is not defined.

The next-hop, advertised-label, and swap-label parameters are optional. If next-hop is configured but no swap-label specified, a swap occurs with label 3, such as, pop and forward to the next-hop. If the next-hop and swap-label are configured, a regular swap is performed. If no parameters are specified, a pop and route is performed.

Values

16 to 1048575

in-label

Specifies the number of labels to send to the peer associated with this FEC.

Values

32 to 1023

pop

Keyword to pop the label and transmit without the label.

interface interface-name

Specifies the name of the interface the label for the originated FEC is swapped to. For an unnumbered interface, this parameter is mandatory since there is no address for the next-hop. For a numbered interface, it is optional.

graceful-restart

Syntax

[no] graceful-restart

Context

config>router>ldp

Platforms

Supported on all 7210 SAS platforms as described in this document.

Description

This command enables graceful restart helper.

The no form of this command disables graceful restart.

Default

no graceful-restart

implicit-null-label

Syntax

[no] implicit-null-label

Context

config>router>ldp

Platforms

Supported on all 7210 SAS platforms as described in this document.

Description

This command enables the use of the implicit null label. Use this command to signal the implicit null option for all LDP FECs for which this node is the egress LER.

The no form of this command disables the signaling of the implicit null label.

Default

no implicit-null-label

maximum-recovery-time

Syntax

maximum-recovery-time interval

no maximum-recovery-time

Context

config>router>ldp

Platforms

Supported on all 7210 SAS platforms as described in this document.

Description

This command configures the local maximum recovery time.

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

Default

maximum-recovery-time 120

Parameters

interval

Specifies the length of time, in seconds.

Values

15 to 1800

neighbor-liveness-time

Syntax

neighbor-liveness-time interval

no neighbor-liveness-time

Context

config>router>ldp

Platforms

Supported on all 7210 SAS platforms as described in this document.

Description

This command configures the neighbor liveness time.

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

Default

neighbor-liveness-time 120

Parameters

interval

Specifies the length of time in seconds.

Values

5 to 300

import

Syntax

import policy-name [policy-name … up to 5 max]

no import

Context

config>router>ldp

Platforms

Supported on all 7210 SAS platforms as described in this document.

Description

This command configures import route policies to determine which label bindings (FECs) are accepted from LDP neighbors. Policies are configured in the config>router>policy-options context.

If no import policy is specified, LDP accepts all label bindings 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 no form of this command removes all policies from the configuration.

Default

no import

Parameters

policy-name

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

label-withdrawal-delay

Syntax

label-withdrawal-delay seconds

Context

config>router>ldp

Platforms

Supported on all 7210 SAS platforms as described in this document.

Description

This command configures the time interval, in seconds, that LDP will delay the withdrawal of the FEC-label bindings it distributed to its neighbors when FEC is deactivated. When the timer expires, LDP sends a label withdrawal for the FEC to all its neighbors. This is applicable only to LDP transport tunnels (IPv4 prefix FECs) and is not applicable to pseudowires (service FECs).

Default

no label-withdrawal-delay

Parameters

seconds

Specifies the time that LDP delays the withdrawal of the FEC-label binding it distributed to its neighbors when FEC is deactivated.

Values

3 to 120

tunnel-down-damp-time

Syntax

tunnel-down-damp-time seconds

no tunnel-down-damp-time

Context

config>router>ldp

Platforms

Supported on all 7210 SAS platforms as described in this document.

Description

This command configures 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 datapath. 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), are not immediately notified. Traffic is still blackholed because the forwarding engine NHLFE has been deprogrammed.

If the FEC gets resolved before the tunnel-down-damp-time timer expires, LDP programs the forwarding engine with the new NHLFE and performs a tunnel modify event in 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.

When there is an upper layer (user of LDP) that depends on the LDP control plane for failover detection, the label-withdrawal-delay and tunnel-down-damp-time options must be set to 0; for example, where a primary pseudowire does not have its own fast failover detection mechanism, and the node depends on the LDP tunnel down event to activate the standby PW.

The no form of this command specifies that tunnel-down events are not damped.

Parameters

seconds

Specifies the time interval, in seconds, that LDP waits before posting a tunnel down event to the TTM.

Values

0 to 20

keepalive

Syntax

keepalive timeout factor

no keepalive

Context

config>router>ldp>interface-parameters>interface>ipv4

config>router>ldp>interface-parameters>ipv4

config>router>ldp>interface-parameters>interface>ipv6 (supported only on 7210 SAS-Mxp)

config>router>ldp>interface-parameters>ipv6 (supported only on 7210 SAS-Mxp)

config>router>ldp>targ-session>ipv4

config>router>ldp>targ-session>ipv6 (supported only on 7210 SAS-Mxp)

config>router>ldp>targ-session>peer

Platforms

Supported on all 7210 SAS platforms as described in this document.

Description

This command configures the time interval, in seconds, that LDP waits before tearing down the session. The value of the keepalive interval is derived from the factor parameter.

If no LDP messages are exchanged for the configured amount of time, the LDP session is torn down. The keepalive timeout is usually three times the value of the keepalive interval. To maintain the session permanently, regardless of the activity, set the timeout value to zero.

When the LDP session is being set up, the keepalive timeout is negotiated to the lower of the two peers. When an operational value is agreed upon, the keepalive factor derives the value of the keepalive interval. The session must be flapped for the new settings to take effect.

The no form of this command at the interface level sets the timeout and factor to the values defined under the interface-parameters level.

The no form of this command at the peer level sets the timeout and factor to the values defined under the targeted-session level.

Default

The keepalive timeout factor default values, which are dependent on the CLI context, are listed in the following table.

Table: Keepalive timeout factor default values

Context

Timeout

Factor

config>router>ldp>if-params

30

3

config>router>ldp>targ-session

40

4

config>router>ldp>if-params>if

Inherits values from interface-parameters context

config>router>ldp>targ-session>peer

Inherits values from targeted-session context

Parameters

timeout

Specifies the time interval, in seconds, that LDP waits before tearing down the session.

Values

3 to 65535

factor

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.

Values

1 to 255

local-lsr-id

Syntax

local-lsr-id {system | interface | interface-name interface-name}

local-lsr-id interface-name interface-name

no local-lsr-id

Context

config>router>ldp>interface-parameters>interface>ipv4

config>router>ldp>interface-parameters>interface>ipv6 (supported only on 7210 SAS-Mxp)

Platforms

Supported on all 7210 SAS platforms as described in this document.

Description

This command configures the use of the local LDP interface address as the LSR ID to establish a link LDP adjacency and session with a directly connected LDP peer.

By default, the LDP session uses the system interface address as the LSR ID unless it is explicitly configured using this command. Although it is required to always configure the system interface on the router for the LDP protocol to come up on the node, there is no requirement to include the system interface in any routing protocol.

At initial configuration, the LDP session to the peer remains down while the interface is down.

If the user changes the LSR ID on the fly between system and interface values while the LDP session is up, LDP immediately tears down the session and attempts to re-establish it using the new LSR ID.

If the interface used as the LSR ID goes down, the LDP session goes down.

When the interface option is selected, the transport connection (TCP) for the link LDP session will also use the address of the local LDP interface as the transport address. If system is the value configured using the config>router>ldp>interface-parameters>interface>transport-address command, it is overridden.

The no form of this command returns to the default behavior of using the system interface address as the LSR ID.

Default

local-lsr-id system

Parameters

interface

Keyword to configure the local LDP interface address as the value of the LSR ID of this LDP LSR.

system

Keyword to configure the system interface address as the value of the LSR ID of this LDP LSR.

interface-name

Specifies the name of the network IP interface, up to 256 characters. An interface name cannot be in the form of an IP address. If the string contains special characters (#, $, spaces, and so on), the entire string must be enclosed within double quotes.

local-lsr-id

Syntax

local-lsr-id interface-name

no local-lsr-id

Context

config>router>ldp>targeted-session>peer

Platforms

Supported on all 7210 SAS platforms as described in this document.

Description

This command enables the use of the address of a specific interface as the LSR-ID for the hello adjacency of a T-LDP session. The interface can be a regular interface or a loopback interface, including the system interface.

By default, a T-LDP session uses the system interface address as the LSR-ID. The system interface must always be configured on the router or the LDP protocol will not come up on the node. There is no requirement to include the system interface in any routing protocol though.

At initial configuration, the T-LDP session will remain down while the specified interface is down. LDP will not try to bring it up using the system interface.

If the user changes the LSR-ID on the fly while the T-LDP session is up, LDP immediately tears down the session and attempts to establish one using the new LSR-ID, regardless of operational state of the newly specified interface.

If the interface used as the LSR-ID goes down, the T-LDP session goes down.

The user-configured LSR-ID is used exclusively for extended peer discovery to establish the T-LDP hello adjacency. It is also used as the transport address for the TCP session of the LDP session when it is bootstrapped by the T-LDP hello adjacency. The user-configured LSR-ID is not used in basic peer discovery to establish a link-level LDP hello adjacency.

The no form of this command returns to the default behavior where the system interface address is used as the LSR-ID.

Default

no local-lsr-id

Parameters

interface-name

Specifies the name of the network IP interface, up to 32 characters. An interface name cannot be in the form of an IP address. If the string contains special characters (#, $, spaces, and so on), the entire string must be enclosed within double quotes.

interface-parameters

Syntax

interface-parameters

Context

config>router>ldp

Platforms

Supported on all 7210 SAS platforms as described in this document.

Description

This command configures LDP interfaces and parameters applied to LDP interfaces.

bfd-enable

Syntax

bfd-enable

no bfd-enable

Context

config>router>ldp>targ-session

config>router>ldp>targ-session>peer

Platforms

Supported on all 7210 SAS platforms as described in this document.

Description

This command enables the use of bidirectional forwarding (BFD) to control the state of the associated protocol interface. By enabling BFD on a specific protocol interface, the state of the protocol interface is tied to the state of the BFD session between the local node and the remote node. The parameters used for the BFD are set via the BFD command under the IP interface.

The no form of this command removes BFD from the associated IGP/BGP protocol adjacency.

Default

no bfd-enable

p2mp-ipv4

Syntax

p2mp-ipv4 {enable | disable}

Context

config>router>ldp>interface-params>interface>ipv4>fec-type-capability

config>router>ldp>interface-params>interface>ipv6>fec-type-capability (supported only on 7210 SAS-Mxp)

Platforms

7210 SAS-T, 7210 SAS-Mxp, 7210 SAS-R6, and 7210 SAS-R12

Description

This command enables and disables the IPv4 P2MP FEC capability on the interface.

Parameters

enable

Keyword to enable the IPv4 P2MP FEC capability.

disable

Keyword to disable the IPv4 P2MP FEC capability.

prefix-ipv4

Syntax

prefix-ipv4 {enable | disable}

Context

config>router>ldp>interface-params>interface>ipv4>fec-type-capability

config>router>ldp>interface-params>interface>ipv6>fec-type-capability (supported only on 7210 SAS-Mxp)

Platforms

Supported on all 7210 SAS platforms as described in this document.

Description

This command enables and disables the IPv4 prefix FEC capability on the interface.

Parameters

enable

Keyword to enable the IPv4 prefix FEC capability.

disable

Keyword to disable the IPv4 prefix FEC capability.

prefix-ipv6

Syntax

prefix-ipv6 {enable | disable}

Context

config>router>ldp>interface-params>interface>ipv4>fec-type-capability

config>router>ldp>interface-params>interface>ipv6>fec-type-capability (supported only on 7210 SAS-Mxp)

Platforms

Supported on all 7210 SAS platforms as described in this document.

Description

This command enables and disables the IPv6 prefix FEC capability on the interface.

Parameters

enable

Keyword to enable the IPv6 prefix FEC capability.

disable

Keyword to disable the IPv6 prefix FEC capability.

hello

Syntax

hello timeout factor

no hello

Context

config>router>ldp>interface-parameters>interface>ipv4

config>router>ldp>interface-parameters>ipv4

config>router>ldp>interface-parameters>interface>ipv6 (supported only on 7210 SAS-Mxp)

config>router>ldp>interface-parameters>ipv6 (supported only on 7210 SAS-Mxp)

config>router>ldp>targ-session>ipv4

config>router>ldp>targ-session>ipv6 (supported only on 7210 SAS-Mxp)

config>router>ldp>targ-session>peer

Platforms

Supported on all 7210 SAS platforms as described in this document.

Description

This command configures the time interval to wait before declaring a neighbor down. The factor parameter derives the Hello interval.

The hold time is local to the system and sent in the Hello messages to the neighbor. The hold time cannot be less than three times the hello interval.

When the LDP session is being set up, the hold down 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 session must be flapped for the new settings to operate.

The no form of this command at the targeted-session level sets the hello timeout and the hello factor to the default values.

The no form of this command at the peer level sets the hello timeout and the hello factor to the value defined under the targeted-session level.

Default

The following table lists the default values for the timeout and factor parameters.

Table: Default values for hello parameters

Context

Timeout

Factor

config>router>ldp>if-params

15

3

config>router>ldp>targ-session

45

3

config>router>ldp>if-params>if

Inherits values from the interface-parameters context

config>router>ldp>targ-session>peer

Inherits values from the targeted-session context

Parameters

timeout

Specifies the time interval, in seconds, that LDP waits before a neighbor goes down.

Values

3 to 65535

factor

Specifies the number of keepalive messages that should be sent on an idle LDP session in the hello timeout interval.

Values

1 to 255

hello-reduction

Syntax

hello-reduction {enable factor | disable}

no hello-reduction

Context

config>router>ldp>targ-session>ipv4

config>router>ldp>targ-session>ipv6 (supported only on 7210 SAS-Mxp)

Platforms

Supported on all 7210 SAS platforms as described in this document.

Description

This command enables the suppression of periodic targeted Hello messages between LDP peers after the targeted LDP session is brought up.

When this feature is enabled, the target Hello adjacency is brought up by advertising the hold-time value configured in the hello timeout parameter for the targeted session. The LSR node starst advertising an exponentially increasing hold-time value in the Hello message as soon as the targeted LDP session to the peer is up. Each new incremented hold-time value is sent in a number of Hello messages equal to the value of the argument factor, which represents the dampening factor, before the next exponential value is advertised. This provides time for the two peers to settle on the new value. When the hold-time reaches the maximum value of 0xffff (binary 65535), the two peers send Hello messages at a frequency of every [(65535-1)/local helloFactor] seconds for the lifetime of the targeted LDP session. For example, if the local Hello factor is 3, Hello messages are sent every 21844 seconds.

The LSR node continues to compute the frequency of sending the Hello messages based on the minimum of its local hold-time value and the one advertised by its peer, as described in RFC 5036. Therefore, for the targeted LDP session to suppress the periodic Hello messages, both peers must bring their advertised hold-time to the maximum value. If one of the LDP peers does not, the frequency of the Hello messages sent by both peers continues to be governed by the smaller of the two hold-time values.

When the user enables the hello reduction option on the LSR node while the targeted LDP session to the peer is operationally up, the change takes effect immediately.That is, the LSR node starts advertising an exponentially increasing hold time value in the Hello message, starting with the current configured hold time value.

When the user disables the hello reduction option while the targeted LDP session to the peer is operationally up, the change in the hold time value from 0xffff (binary 65535) to the user-configured value for this peer takes effect immediately. The local LSR immediately advertises the value of the user-configured hold time and does not wait until the next scheduled time to send a Hello to make sure the peer adjusts its local hold timeout value immediately.

In general, any configuration change to the parameters of the T-LDP Hello adjacency (modifying the hello adjacency Hello timeout or factor, enabling or disabling hello reduction, or modifying the hello reduction factor) causes the LSR node to immediately trigger an updated Hello message with the updated hold-time value without waiting for the next scheduled time to send a Hello.

The no form of this command disables the hello reduction feature.

Default

no hello-reduction

Parameters

disable

Keyword to disable hello reduction.

factor

Specifies the hello reduction dampening factor.

Values

3 to 20

interface

Syntax

interface ip-int-name [dual-stack]

no interface ip-int-name

Context

config>router>ldp>if-params

Platforms

Supported on all 7210 SAS platforms as described in this document.

Description

This command enables LDP on the specified IP interface.

The LDP interface must be disabled using the shutdown command before it can be deleted.

The no form of this command deletes the LDP interface and all configuration information associated with the LDP interface.

Parameters

ip-int-name

Specifies the name of an existing interface. If the string contains special characters (#, $, spaces, and so on), the entire string must be enclosed within double quotes.

dual-stack

Optional keyword that allows the user to explicitly indicate whether this interface should automatically create the IPv4 context. With the introduction of LDP IPv6, the creation of the interface does not automatically imply it is used for IPv4, simular to earlier IPv4 only interfaces. Therefore, the dual-stack keyword is an indication to the system that the user manually enables the IPv4, IPv6, or the dual-stack IPv4 and IPv6 contexts.

The following applies to the dual-stack keyword:
  • If this keyword is configured, the IPv4 interface context is not created automatically. If it is not configured, the IPv4 interface context is created similar to the single stack LDP IPv4 interface behavior.
  • This keyword is always displayed in a configuration.
  • When entering an already configured interface, configuring this keyword is not required; it is ignored if configured.
  • When deleting a configured interface, this keyword is not accepted in the no form of this command.

bfd-enable

Syntax

bfd-enable

no bfd-enable

Context

config>router>ldp>interface-parameters>interface>ipv4

Platforms

Supported on all 7210 SAS platforms as described in this document.

Description

This command enables tracking of the Hello adjacency to an LDP peer using BFD.

When this command is enabled on an LDP interface, LDP registers with BFD and starts tracking the LSR ID of all peers with which it formed Hello adjacencies over that LDP interface. The LDP hello mechanism is used to determine the remote address to be used for the BFD session. The parameters used for the BFD session, that is, transmit-interval, receive-interval, and multiplier, are those configured under the IP interface in existing implementation: config>router>interface>bfd.

When multiple links exist to the same LDP peer, a Hello adjacency is established over each link and a separate BFD session is enabled on each LDP interface. If a BFD session times out on a specific link, LDP will immediately associate the LDP session with one of the remaining Hello adjacencies and trigger the LDP FRR procedures. As soon as the last Hello adjacency goes down because of BFD timing out, the LDP session goes down and the LDP FRR procedures will be triggered.

The no form of this command disables BFD on the LDP interface.

Default

no bfd-enable

ipv4

Syntax

ipv4

Context

config>router>ldp>interface-parameters>interface

config>router>ldp>interface-parameters

config>router>ldp>targeted-session

Platforms

Supported on all 7210 SAS platforms as described in this document.

Description

Commands in this context configure IPv4 LDP parameters for the interface.

transport-address

Syntax

transport-address {interface | system}

no transport-address

Context

config>router>ldp>interface-parameters>interface>ipv4

config>router>ldp>interface-parameters>ipv4

config>router>ldp>interface-parameters>interface>ipv6 (supported only on the 7210 SAS-Mxp)

config>router>ldp>interface-parameters>ipv6 (supported only on the 7210 SAS-Mxp)

Platforms

Supported on all 7210 SAS platforms as described in this document.

Description

This command configures the transport address used when setting up LDP TCP sessions. The transport address, which can be set to interface or system, can be configured globally (applies to all LDP interfaces) or per interface. The most specific value is used.

With this command, you can set up the LDP interface to the connection, which can be set to the interface address or the system address. However, there can be an issue of which address to use when there are parallel adjacencies. This situation can also occur with a link and a targeted adjacency, because targeted adjacencies request the session to be set up only to the system IP address.

The transport-address value should not be interface if multiple interfaces exist between two LDP neighbors. The chosen TCP endpoint depends on the first adjacency to be formed. That is, if one LDP interface is set up as transport-address interface and another as transport-address system, the TCP endpoint addresses are determined depending on which adjacency was set up first, the TCP. After that, because the Hello message contains the LSR ID, the LDP session can be checked to verify that it is set up and match the adjacency to the session.

For any ILDP interface, as the local-lsr-id parameter is changed to interface, the transport-address configuration loses effectiveness because it is ignored and the ILDP sessions always uses the relevant interface IP address as transport address even though system is configured.

The no form of this command at the global level sets the transport address to the default value.

The no form of this command at the interface level sets the transport address to the value defined under the global level.

Default

system

Parameters

interface

Keyword to specify that the IP interface address is used to set up the LDP session between neighbors. The transport address interface cannot be used if multiple interfaces exist between two neighbors, because only one LDP session is set up between two neighbors.

system

Keyword to specify that the system IP address is used to set up the LDP session between neighbors.

prefer-tunnel-in-tunnel

Syntax

[no] prefer-tunnel-in-tunnel

Context

config>router>ldp

Platforms

Supported on all 7210 SAS platforms as described in this document.

Description

This command specifies to use tunnel-in-tunnel over a simple LDP tunnel. Specifically, the user packets for LDP FECs learned over this targeted LDP session can be sent inside an RSVP LSP, which terminates on the same egress router as the destination of the targeted LDP session. The user can specify an explicit list of RSVP LSP tunnels under the targeted LDP session or LDP will perform a lookup in the TTM for the best RSVP LSP. In the former case, only the specified LSPs will be considered to tunnel LDP user packets. In the latter case, all LSPs available to the TTM and that terminate on the same egress router as this targeted LDP session will be considered. In both cases, the metric specified under the LSP configuration is used to control this selection.

The lookup in the TTM will prefer an LDP tunnel over an LDP-over-RSVP tunnel if both are available. The tunneling operates on the data plane only. Control packets of this targeted LDP session are sent over the IGP path.

ipv6

Syntax

ipv6

Context

config>router>ldp>interface-parameters>interface

config>router>ldp>interface-parameters

config>router>ldp>targeted-session

Platforms

7210 SAS-Mxp

Description

Commands in this context configure IPv6 LDP parameters for the interface.