OcNOS-SP : Multi-Protocol Label Switching Guide : Multi-Protocol Label Switching Configuration Guide : MPLS LDP-IGP Synchronization : LDP-IGP Synchronization with IS-IS
LDP-IGP Synchronization with IS-IS
When IGP synchronization is enabled on an IS-IS enabled interfaces, IS-IS sends Maximum/Normal cost based on LDP session or Up state on interfaces until hold-down-timer expires or synchronization is achieved.
Before configuring LDP-IGP synchronization, the NSM, IS-IS and LDP configurations must be completed. The tables below contain examples of how this is done.
RTR1 - NSM
 
#configure terminal
Enter configuration mode.
(config)#interface xe11
Enter interface mode.
(config-if)#ip address 10.10.10.1/24
Set the IP address of the xe11 to 10.10.10.1/24.
(config-if)#label-switching
Enable label switching on xe11.
(config-if)#exit
Exit interface mode.
(config)#interface lo
Specify the loopback (lo) interface to be configured.
(config-if)#ip address 1.1.1.1/32 secondary
Set the IP address of the loopback interface to 1.1.1.1/32.
(config-if)#commit
Commit the transaction.
RTR1 - IS-IS
 
(config)#router isis 1
Configure the IS-IS routing instance and specify the TAG (1). The TAG should be a WORD - ISO routing area tag.
(config-router)#is-type level-1
Define the IS to the specified level of routing for router.
(config-router)#net 49.0001.0000.0000.0001.00
Configure the Network Entity Title (NET) for the instance.
(config-router)#exit
Exit the Router mode and return to the Configure mode.
(config)#interface xe11
Enter interface mode.
(config-if)#ip router isis 1
Configure IS-IS IPv4 routing on the interface with IS-IS tag instance 1.
(config-if)#isis circuit-type level-1
Define the circuit type for the interface on which IS-IS runs and associate the level 1.
(config-if)#exit
Exit interface mode.
(config)#interface lo
Enter interface mode for the loopback interface (lo).
(config-if)#ip router isis 1
Configure IS-IS IPv4 routing on the interface with IS-IS tag instance 1.
(config-if)#isis circuit-type level-1
Define the circuit type for the interface on which IS-IS runs and associate the level 1.
(config-if)#commit
Commit the transaction.
RTR1 - LDP
 
(config)#router ldp
Enter Router mode for LDP.
(config-router)#router-id 1.1.1.1
Set the router ID to IP address 1.1.1.1.
(config-router)#transport-address ipv4 1.1.1.1
Configure the transport address for IPV4 (for IPv6 use an IPv6 address) to use for a TCP session over which LDP will run.
Note: It is preferable to use the loopback address as transport address.
(config-router)#exit
Exit the Router mode and return to the Configure mode.
(config)#interface xe11
Enter interface mode.
(config-if)#enable-ldp ipv4
Enable LDP for IPv4 on xe11.
(config-if)#commit
Commit the transaction.
RTR2 - NSM
 
#configure terminal
Enter configuration mode
(config)#interface xe11
Enter interface mode.
(config-if)#ip address 10.10.10.2/24
Set the IP address of xe11 to 10.10.10.2/24
(config-if)#label-switching
Enable label switching on interface xe11.
(config-if)#exit
Exit interface mode.
(config)#interface lo
Specify the loopback (lo) interface to be configured.
(config-if)#ip address 2.2.2.2/32 secondary
Set the IP address of the loopback interface to 2.2.2.2/32.
(config-if)#commit
Commit the transaction.
RTR2 - IS-IS
 
(config)#router isis 1
Configure the IS-IS routing instance and specify the TAG as 1. The TAG should be a WORD - ISO routing area tag.
(config-router)#is-type level-1
Define the IS to the specified level of routing for router.
(config-router)#net 49.0001.0000.0000.0002.00
Configure the Network Entity Title (NET) for the instance.
(config-router)#exit
Exit the Router mode and return to the Configure mode.
(config)#interface xe11
Enter interface mode.
(config-if)#ip router isis 1
Configure IS-IS IPv4 routing on the interface with is-is tag instance 1.
(config-if)#isis circuit-type level-1
Define the circuit type for the interface on which IS-IS runs and associate the level type (1).
(config-if)#exit
Exit interface mode.
(config)#interface lo
Enter interface mode for the loopback (lo) interface.
(config-if)#ip router isis 1
Configure IS-IS IPv4 routing on the interface with IS-IS tag instance 1.
(config-if)#isis circuit-type level-1
Define the circuit type for the interface on which IS-IS runs and associate the level 1.
(config-if)#commit
Commit the transaction.
RTR2 - LDP
 
(config)#router ldp
Enter Router mode for LDP.
(config-router)#router-id 2.2.2.2
Set the router ID to IP address 2.2.2.2.
(config-router)#transport-address ipv4 2.2.2.2
Configure the transport address for IPv4 (for IPv6 use an IPv6 address) to use for a TCP session over which LDP will run.
Note: It is preferable to use the loopback address as transport address.
(config-router)#exit
Exit the Router mode and return to the Configure mode.
(config)#interface xe11
Enter interface mode.
(config-if)#enable-ldp ipv4
Enable LDP for IPv4 on xe11.
(config-if)#commit
Commit the transaction.
Validation
R1#show clns neighbors
 
Total number of L1 adjacencies: 1
Total number of L2 adjacencies: 0
Total number of adjacencies: 1
Tag 1: VRF : default
System Id Interface SNPA State Holdtime Type Protocol
0000.0000.0002 xe11 6cb9.c5cf.da69 Up 24 L1 IS-IS
 
R2#show clns neighbors
 
Total number of L1 adjacencies: 1
Total number of L2 adjacencies: 0
Total number of adjacencies: 1
Tag 1: VRF : default
System Id Interface SNPA State Holdtime Type Protocol
0000.0000.0001 xe11 b86a.97d1.24d1 Up 9 L1 IS-IS
 
R1#show clns is-neighbors
 
Tag 1: VRF : default
System Id Interface State Type Priority Circuit Id
0000.0000.0002 xe11 Up L1 64 0000.0000.0001.01
 
R2#show clns is-neighbors
 
Tag 1: VRF : default
System Id Interface State Type Priority Circuit Id
0000.0000.0001 xe11 Up L1 64 0000.0000.0001.01
 
R1#show ldp session
Peer IP Address IF Name My Role State KeepAlive UpTime
2.2.2.2 xe11 Passive OPERATIONAL 30 00:08:08
 
R1#show ldp adjacency
IP Address Mode Intf Name Holdtime LDP-Identifier
10.10.10.2 Interface xe11 15 2.2.2.2:0
 
R2#show ldp session
Peer IP Address IF Name My Role State KeepAlive UpTime
1.1.1.1 xe11 Active OPERATIONAL 30 00:08:24
 
R2#show ldp adjacency
IP Address Mode Intf Name Holdtime LDP-Identifier
10.10.10.1 Interface xe11 15 1.1.1.1:0
 
R1#show isis interface xe11
xe11 is up, line protocol is up
Routing Protocol: IS-IS (1)
Network Type: Broadcast
Circuit Type: level-1
Local circuit ID: 0x01
Extended Local circuit ID: 0x0000271C
Local SNPA: b86a.97d1.24d1
IP interface address:
10.10.10.1/24
IPv6 interface address:
fe80::ba6a:97ff:fed1:24d1/64
Level-1 Metric: 10/10, Priority: 64, Circuit ID: 0000.0000.0001.01
Number of active level-1 adjacencies: 1
Level-1 LSP MTU: 1492
Next IS-IS LAN Level-1 Hello in 792 milliseconds
 
R2#show isis interface xe11
xe11 is up, line protocol is up
Routing Protocol: IS-IS (1)
Network Type: Broadcast
Circuit Type: level-1
Local circuit ID: 0x01
Extended Local circuit ID: 0x0000271B
Local SNPA: 6cb9.c5cf.da69
IP interface address:
10.10.10.2/24
IPv6 interface address:
fe80::6eb9:c5ff:fecf:da69/64
Level-1 Metric: 10/10, Priority: 64, Circuit ID: 0000.0000.0001.01
Number of active level-1 adjacencies: 1
Level-1 LSP MTU: 1492
Next IS-IS LAN Level-1 Hello in 1 seconds
 
 
R1#show isis database detail
Tag 1: VRF : default
IS-IS Level-1 Link State Database:
LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/OL
0000.0000.0001.00-00* 0x00000002 0xB193 516 0/0/0
Area Address: 49.0001
NLPID: 0xCC
IP Address: 10.10.10.1
Metric: 10 IS 0000.0000.0001.01
Metric: 10 IP 10.10.10.0 255.255.255.0
Metric: 10 IP 1.1.1.1 255.255.255.255
0000.0000.0001.01-00* 0x00000001 0x1FBD 516 0/0/0
Metric: 0 IS 0000.0000.0001.00
Metric: 0 IS 0000.0000.0002.00
0000.0000.0002.00-00 0x00000002 0x84BA 519 0/0/0
Area Address: 49.0001
NLPID: 0xCC
IP Address: 10.10.10.2
Metric: 10 IS 0000.0000.0001.01
Metric: 10 IP 10.10.10.0 255.255.255.0
Metric: 10 IP 2.2.2.2 255.255.255.255
 
R2#show isis database detail
Tag 1: VRF : default
IS-IS Level-1 Link State Database:
LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/OL
0000.0000.0001.00-00 0x00000002 0xB193 521 0/0/0
Area Address: 49.0001
NLPID: 0xCC
IP Address: 10.10.10.1
Metric: 10 IS 0000.0000.0001.01
Metric: 10 IP 10.10.10.0 255.255.255.0
Metric: 10 IP 1.1.1.1 255.255.255.255
0000.0000.0001.01-00 0x00000001 0x1FBD 521 0/0/0
Metric: 0 IS 0000.0000.0001.00
Metric: 0 IS 0000.0000.0002.00
0000.0000.0002.00-00* 0x00000002 0x84BA 526 0/0/0
Area Address: 49.0001
NLPID: 0xCC
IP Address: 10.10.10.2
Metric: 10 IS 0000.0000.0001.01
Metric: 10 IP 10.10.10.0 255.255.255.0
Metric: 10 IP 2.2.2.2 255.255.255.255
LDP-IGP SYNC Configuration
Now that NSM, IS-IS and LDP are all enabled, the LDP-IGP synchronization can be configured.
RTR1
 
(config)#interface xe11
Enter interface mode.
(config-if)#mpls ldp-igp sync isis level-1 holddown-timer 700
Configure LDP-IGP Synchronization for interface xe11 belonging to an IS-IS process with corresponding IS-IS level.700 seconds is the holddown-timer value for IGP to wait until LDP converges.
The values level-1|level-2-only|level-1-2 identify the IS-IS level instance. The interface can be acting on any level, but the sync is applicable only when it matches with the level given in IGP sync command.
IS-IS: This command is part of ISIS Process.
Default: Mandatory configuration. No default option.
Note: The holddown-timer Range is 1 to 2147483 seconds. If no holddown timer is configured, IGP waits indefinitely for LDP to Converge. Use the command mpls ldp-igp sync is-is <level-type> to configure without a holddown-timer.
(config-if)#mpls ldp-igp sync-delay 55
Set the time delay in seconds for the notification of LDP convergence to IGP. This is not applicable for notification of non-convergence. Range is 5 to 60 seconds. This command is optional.
LDP: This command is part of LDP Process.
Default: If not configured, the delay is 0 seconds.
(config-if)#commit
Commit the transaction.
LDP-IGP SYNC Configuration
Now that NSM, IS-IS and LDP are all enabled, the LDP-IGP synchronization can be configured.
RTR2
 
(config)#interface xe11
Enter interface mode.
(config-if)#mpls ldp-igp sync isis level-1 holddown-timer 700
Configure LDP-IGP Synchronization for interface xe11 belonging to an IS-IS process with corresponding IS-IS level.700 secs is the holddown-timer value for IGP to wait until LDP converges.
The parameters level-1|level-2-only|level-1-2 identify the IS-IS instance level. The interface can be acting on any level, but sync is applicable only when it matches with the level given in IGP sync command.
IS-IS: This command is part of IS-IS Process.
Default: Mandatory configuration. No default option.
Note: The holddown-timer Range is 1 to 2147483 seconds. If no holddown timer is configured, IGP waits indefinitely for LDP to Converge. Use command mpls ldp-igp sync is-is <level-type> to configure without a holddown-timer.
(config-if)#mpls ldp-igp sync-delay 55
Set the time delay in seconds for notification of LDP convergence to IGP. This is not applicable for notification of non-convergence. Range is 5 to 60 seconds. This command is optional.
LDP: This command is part of LDP Process.
Default: If not configured, the delay is 0 seconds.
(config-if)#commit
Commit the transaction.
RTR1 Validation
When LDP IGP SYNC is Configured with hold-down and sync-delay timer
R1#show isis interface xe11
xe11 is up, line protocol is up
Routing Protocol: IS-IS (1)
Network Type: Broadcast
Circuit Type: level-1
Local circuit ID: 0x01
Extended Local circuit ID: 0x0000271C
Local SNPA: b86a.97d1.24d1
IP interface address:
10.10.10.1/24
IPv6 interface address:
fe80::ba6a:97ff:fed1:24d1/64
LDP-ISIS Sync Configured
Holddown timer = 700 seconds, Remaining time = 0 seconds
Level-1 Metric: 10/10, Priority: 64, Circuit ID: 0000.0000.0001.01
Number of active level-1 adjacencies: 1
Level-1 LSP MTU: 1492
Next IS-IS LAN Level-1 Hello in 420 milliseconds
 
R1#show mpls ldp igp sync
xe11 is up, line protocol is up
LDP configured; LDP-IGP Synchronization enabled.
Session IP Address : 2.2.2.2
Sync status: Achieved
Delay timer: Configured, 55 seconds, Not Running
R1#
RTR2 Validation
R2#show isis interface xe11
xe11 is up, line protocol is up
Routing Protocol: IS-IS (1)
Network Type: Broadcast
Circuit Type: level-1
Local circuit ID: 0x01
Extended Local circuit ID: 0x0000271B
Local SNPA: 6cb9.c5cf.da69
IP interface address:
10.10.10.2/24
IPv6 interface address:
fe80::6eb9:c5ff:fecf:da69/64
LDP-ISIS Sync Configured
Holddown timer = 700 seconds, Remaining time = 0 seconds
Level-1 Metric: 10/10, Priority: 64, Circuit ID: 0000.0000.0001.01
Number of active level-1 adjacencies: 1
Level-1 LSP MTU: 1492
Next IS-IS LAN Level-1 Hello in 4 seconds
 
R2#show mpls ldp igp sync
xe11 is up, line protocol is up
LDP configured; LDP-IGP Synchronization enabled.
Session IP Address : 1.1.1.1
Sync status: Achieved
Delay timer: Configured, 55 seconds, Not Running
 
Last modified date: 10/17/2023