Interface Metric
You can make a route the preferred route by changing its metric. In this example, the cost has been configured to make R3 the next hop for R1.
The default metric for each interface is 10. Interface eth2 on R2 has a metric of 20, and Interface eth2 on R3 has a metric of 30. The total cost to reach 9999::/64 (R4) through R2 and R3 is computed as follows: R2: 10+20 = 30 R3: 10+30 = 40
In this topology, R1 chooses R2 as its next hop for destination 9999::/64.
Note: Below configuration is applicable for narrow (non-wide) metric-style. Use the "metric-style wide" under isis instance and "isis wide-metric < 1-16777214>" under interface mode CLI’s to configure Wide metric.
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Figure 7-57: Configure IS-IS Metric
Configuration
R1
#configure terminal | Enter configure mode. |
(config)#interface eth1 | Enter interface mode. |
(config-if)#ipv6 router isis ABC | Enable IS-IS routing on an interface for area 49(ABC). |
(config-if)#exit | Exit interface mode. |
(config)#interface eth2 | Enter interface mode. |
(config-if)#ipv6 router isis ABC | Enable IS-IS routing on an interface for area 49(ABC). |
(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 49.0100.0000.0000.0001.00 | Set a Network Entity Title for this instance, specifying the area address and the system ID. |
(config-router)#end | Exit current mode and enter privilege mode. |
R2
(config)#interface eth2 | Enter interface mode. |
(config-if)#ipv6 router isis ABC | Enable IS-IS routing on an interface for area 49 (ABC). |
(config-if)#exit | Exit interface mode. |
(config)#interface eth3 | Enter interface mode. |
(config-if)#ipv6 router isis ABC | Enable IS-IS routing on an interface for area 49 (ABC). |
(config-if)#isis metric 20 | Set the value of IS-IS metric (on eth2) to 20. |
(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 49.0100.0000.0000.0002.00 | Set a Network Entity Title for this instance, specifying the area address and the system ID. |
R3
(config)#interface eth1 | Enter interface mode. |
(config-if)#ipv6 router isis ABC | Enable IS-IS routing on an interface for area 49 (ABC). |
(config-if)#exit | Exit interface mode. |
(config)#interface eth2 | Enter interface mode. |
(config-if)#ipv6 router isis ABC | Enable IS-IS routing on an interface for area 49 (ABC). |
(config-if)#isis metric 30 | Set the value of IS-IS metric (on eth2) to 30. |
(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 49.0100.0000.0000.0003.00 | Set a Network Entity Title for this instance, specifying the area address and the system ID. |
R4
(config)#interface eth1 | Enter interface mode. |
(config-if)#ipv6 router isis ABC | Enable IS-IS routing on an interface for area 49 (ABC). |
(config-if)#exit | Exit interface mode. |
(config)#interface eth2 | Enter interface mode. |
(config-if)#ipv6 address 9999::1/64 | Configure ipv6 address in eth2 |
(config-if)#exit | Exit interface mode. |
(config)#interface eth3 | Enter interface mode. |
(config-if)#ipv6 router isis ABC | Enable IS-IS routing on an interface for area 49 (ABC). |
(config-if)#ipv6 address 2000::2/64 | Configure IPv6 address on interface. |
(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 49.0100.0000.0000.0004.00 | Set a Network Entity Title for this instance, specifying the area address and the system ID. |
(config-router)#address-family ipv6 | Enter ipv6 address family. |
(config-router-af)#redistribute connected | Enable redistribution of connected routes into ISIS process |
(config-router-af)#end | Exit current mode and enter privilege mode |
Validation
R1#show clns neighbors
Total number of L1 adjacencies: 0
Total number of L2 adjacencies: 2
Total number of adjacencies: 2
Tag ABC: VRF : default
System Id Interface SNPA State Holdtime Type Protocol
0000.0000.0002 eth2 b86a.97c4.31c5 Up 25 L2 IS-IS
0000.0000.0003 eth1 b86a.97c9.3cc5 Up 26 L2 IS-IS
R1#
R2#show clns neighbors
Total number of L1 adjacencies: 0
Total number of L2 adjacencies: 2
Total number of adjacencies: 2
Tag ABC: VRF : default
System Id Interface SNPA State Holdtime Type Protocol
0000.0000.0004 eth3 b86a.97c7.32c5 Up 7 L2 IS-IS
0000.0000.0001 eth2 b86a.97cb.3ec5 Up 6 L2 IS-IS
R2#
R3#show clns neighbors
Total number of L1 adjacencies: 0
Total number of L2 adjacencies: 2
Total number of adjacencies: 2
Tag ABC: VRF : default
System Id Interface SNPA State Holdtime Type Protocol
0000.0000.0004 eth2 b86a.97c7.32c5 Up 22 L2 IS-IS
0000.0000.0001 eth1 b86a.97cb.3ec5 Up 7 L2 IS-IS
R3#
R4#show clns neighbors
Total number of L1 adjacencies: 0
Total number of L2 adjacencies: 2
Total number of adjacencies: 2
Tag ABC: VRF : default
System Id Interface SNPA State Holdtime Type Protocol
0000.0000.0002 eth3 b86a.97c4.31c5 Up 22 L2 IS-IS
0000.0000.0003 eth1 b86a.97c9.3cc5 Up 7 L2 IS-IS
R4#
R1#show ipv6 isis route
Codes: C - connected, E - external, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, D - discard, e - external metric
Tag ABC: VRF : default
C 1000::/64 [10]
via ::, ce0
L2 2000::/64 [30]
via fe80::ce37:abff:fe87:3a74, ce0
C 3000::/64 [10]
via ::, xe14
L2 4000::/64 [40]
via fe80::ba6a:97ff:fecf:3ad4, xe14
via fe80::ce37:abff:fe87:3a74, ce0
L2 9999::/64 [30]
via fe80::ce37:abff:fe87:3a74, ce0
R1#
Last modified date: 07-13-2023