Set Priority
This example describes how to set the priority for an interface. Set a high priority for a router to make it the Designated IS (DIS). Router R2 is configured to have a priority of 125, this is higher than the default priority (64) of R1. This makes R2 the DIS.
Topology
Figure 13-102: Set IS-IS Priority
Configuration
R1
(config)#interface eth1 | Enter interface mode. |
(config-if)#ip router isis ABC | Enable IS-IS routing on an interface for area 49 (ABC). |
(config)#ip address 21.21.21.2/24 | Configure IP address on interface. |
(config-if)#commit | Commit candidate configuration to the running configuration |
(config-if)#exit | Exit interface mode. |
(config)#router isis ABC | Create an IS-IS routing instance for area 49 (ABC). |
(config-router)#is-type level-2-only | Configure instance as level-2-only routing. |
(config-router)#net 49.0000.0000.0001.00 | Set a Network Entity Title for this instance, specifying the area address and the system ID. |
(config-router)#commit | Commit candidate configuration to the running configuration |
R2
(config)#interface eth1 | Enter interface mode. |
(config)#ip address 21.21.21.1/24 | Configure IP address on interface. |
(config-if)#ip router isis ABC | Enable IS-IS routing on an interface for area 49 (ABC). |
(config-if)#isis priority 125 | Specify the router priority to a higher priority (125) to make R2 the designated IS (DIS). |
(config-if)#commit | Commit candidate configuration to the running configuration |
(config-if)#exit | Exit interface mode. |
(config)#router isis ABC | Create an IS-IS routing instance for area 49 (ABC). |
(config-router)#is-type level-2-only | Configure instance as level-2-only routing. |
(config-router)#net 49.0000.0000.0002.00 | Set a Network Entity Title for this instance, specifying the area address and the system ID. |
Validation
R1#show clns neighbors
Total number of L1 adjacencies: 0
Total number of L2 adjacencies: 1
Total number of adjacencies: 1
Tag ABC: VRF : default
System Id Interface SNPA State Holdtime Type Protocol
0000.0000.0002 eth1 5254.002a.230a Up 6 L2 IS-IS
R2#show clns neighbors
Total number of L1 adjacencies: 0
Total number of L2 adjacencies: 1
Total number of adjacencies: 1
Tag ABC: VRF : default
System Id Interface SNPA State Holdtime Type Protocol
0000.0000.0001 eth1 5254.00dc.0b76 Up 21 L2 IS-IS
R1#show clns is-neighbors
Tag ABC: VRF : default
System Id Interface State Type Priority Circuit Id
0000.0000.0002 eth1 Up L2 125 0000.0000.0002.01
R2#show clns is-neighbors
Tag ABC: VRF : default
System Id Interface State Type Priority Circuit Id
0000.0000.0001 eth1 Up L2 64 0000.0000.0002.01
R1#show isis interface
eth1 is up, line protocol is up
Routing Protocol: IS-IS (ABC)
Network Type: Broadcast
Circuit Type: level-1-2
Local circuit ID: 0x01
Extended Local circuit ID: 0x00000003
Local SNPA: 5254.00dc.0b76
IP interface address:
21.21.21.2/24
IPv6 interface address:
fe80::5054:ff:fedc:b76/64
Level-2 Metric: 10/10, Priority: 64, Circuit ID: 0000.0000.0002.01
Number of active level-2 adjacencies: 1
Level-2 LSP MTU: 1492
Next IS-IS LAN Level-2 Hello in 1 seconds
R2#show isis interface
eth1 is up, line protocol is up
Routing Protocol: IS-IS (ABC)
Network Type: Broadcast
Circuit Type: level-1-2
Local circuit ID: 0x01
Extended Local circuit ID: 0x00000003
Local SNPA: 5254.002a.230a
IP interface address:
21.21.21.1/24
IPv6 interface address:
fe80::5054:ff:fe2a:230a/64
Level-2 Metric: 10/10, Priority: 125, Circuit ID: 0000.0000.0002.01
Number of active level-2 adjacencies: 1
Level-2 LSP MTU: 1492
Next IS-IS LAN Level-2 Hello in 737 milliseconds
Last modified date: 10/16/2023