Route Summarization
Route summarization makes the routing table smaller, but still allows complete IP connectivity.
The following example consists of a three-router topology, in which R2 is doing the summarization. In this example, R1 is the L1 router, R2 is the L1/L2 router doing the summarization, and R3 is the L2 router. The following configuration is given only for R2, assuming that the adjacencies with R1 and R3 are already up, and the route tables with the appropriate routes are already populated.
Topology
Figure 14-119: Route Summarization Topology
Configuration
R1
#configure terminal | Enter configure mode. |
(config)#interface eth1 | Enter interface mode. |
(config-if)#ipv6 router isis ABC | Enable IS-ISv6 routing on an interface for area 49(ABC). |
(config-if)#ipv6 address 1000::1/64 | Configure IPv6 address on interface. |
(config-if)#isis circuit-type level-1 | Set the circuit type as level-1 for the 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-1 | Configure instance as level-1 routing. |
(config-if)#commit | Commit candidate configuration to the running configuration |
(config-router)#net 49.0001.0000.0000.0001.00 | 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
#configure terminal | Enter configure mode. |
(config)#interface eth1 | Enter interface mode. |
(config-if)#ipv6 router isis ABC | Enable IS-ISv6 routing on an interface for area 49(ABC). |
(config-if)#ipv6 address 1000::2/64 | Configure IPv6 address on interface. |
(config-if)#isis circuit-type level-1 | Set the circuit type as level-1 for the interface. |
(config-if)#commit | Commit candidate configuration to the running configuration |
(config-if)#exit | Exit interface mode. |
(config)#interface eth2 | Enter interface mode. |
(config-if)#ipv6 router isis ABC | Enable IS-ISv6 routing on an interface for area 49(ABC). |
(config-if)#ipv6 address 2000::1/64 | Configure IPv6 address on interface. |
(config-if)#isis circuit-type level-2-only | Set the circuit type as level-2-only for the 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)#net 49.0001.0000.0000.0002.00 | Set a Network Entity Title for this instance, specifying the area address and the system ID. |
(config-router)#address-family ipv6 | Enter 'address-family ipv6' mode, where users can configure IPv6 routing specific configuration. |
(config-router-af)#redistribute isis level-2 into level-1 | Enable redistribution of isis routes from level-2 into level-1 |
(config-router-af)#summary-prefix 11:1:1:1::/64 level-1 metric 58 | Configure the summary prefix to summarize IPv6 reachability information. |
(config-if)#commit | Commit candidate configuration to the running configuration |
(config-router-af)#exit-address-family | Exit address family mode. |
(config-router)#exit | Exit router mode. |
R3
#configure terminal | Enter configure mode. |
(config)#ipv6 route 11:1:1:1:1:1::/96 eth2 | Configure ipv6 static route. |
(config)#ipv6 route 11:1:1:1:2:1::/96 eth2 | Configure ipv6 static route. |
(config)#ipv6 route 11:1:1:1:3:1::/96 eth2 | Configure ipv6 static route. |
(config)#interface eth2 | Enter interface mode. |
(config-if)#ipv6 router isis ABC | Enable IS-ISv6 routing on an interface for area 49(ABC). |
(config-if)#ipv6 address 2000::2/64 | Configure IPv6 address on interface. |
(config-if)#isis circuit-type level-2-only | Set the circuit type as level-2-only for the 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)#net 49.0001.0000.0000.0003.00 | Set a Network Entity Title for this instance, specifying the area address and the system ID. |
(config-router)# is-type level-2-only | Configure instance as level-2 -onlyrouting. |
(config-router)#address-family ipv6 | Enter 'address-family ipv6' mode, where users can configure IPv6 routing specific configuration. |
(config-router-af)#redistribute static | Enable redistribution of static routes into ISIS instance. |
(config-router-af)#commit | Commit candidate configuration to the running configuration |
(config-router-af)#end | Exit the current mode and enter privilege mode. |
Validation
R1#show clns neighbors
Total number of L1 adjacencies: 1
Total number of L2 adjacencies: 0
Total number of adjacencies: 1
Tag ABC: VRF : default
System Id Interface SNPA State Holdtime Type Protocol
0000.0000.0002 eth1 b86a.97c4.31c5 Up 21 L1 IS-IS
R2#show clns neighbors
Total number of L1 adjacencies: 1
Total number of L2 adjacencies: 1
Total number of adjacencies: 2
Tag ABC: VRF : default
System Id Interface SNPA State Holdtime Type Protocol
0000.0000.0003 eth2 b86a.97c7.32c5 Up 8 L2 IS-IS
0000.0000.0001 eth1 b86a.97cb.3ec5 Up 8 L1 IS-IS
R3#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 eth2 b86a.97c4.31c5 Up 20 L2 IS-IS
R1#show ipv6 route isis
IP Route Table for VRF "default"
i ia 11:1:1:1::/64 [115/68] via fe80::eac5:7aff:fe6b:732e, eth1, 00:00:25
i ia 2000::/64 [115/20] via fe80::eac5:7aff:fe6b:732e, eth1, 00:01:15
R1#
R2#show ipv6 route isis
IP Route Table for VRF "default"
i 11:1:1:1::/64 [115/0] via ::, Null, 00:01:56
i L2 11:1:1:1:1:1::/96 [115/10] via fe80::eac5:7aff:fe7d:5332, eth2, 00:01:56
i L2 11:1:1:1:2:1::/96 [115/10] via fe80::eac5:7aff:fe7d:5332, eth2, 00:01:56
i L2 11:1:1:1:3:1::/96 [115/10] via fe80::eac5:7aff:fe7d:5332, eth2, 00:01:56
R2#
R3#show ipv6 route isis
IP Route Table for VRF "default"
i L2 1000::/64 [115/20] via fe80::eac5:7aff:fe6b:7332, eth2, 00:02:08
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
ia 11:1:1:1::/64 [68]
via fe80::eac5:7aff:fe6b:732e, eth1
C 1000::/64 [10]
via ::, xe16
ia 2000::/64 [20]
via fe80::eac5:7aff:fe6b:732e, eth1
R2#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
D 11:1:1:1::/64 [0]
via ::
L2 11:1:1:1:1:1::/96 [10]
via fe80::eac5:7aff:fe7d:5332, eth2
L2 11:1:1:1:2:1::/96 [10]
via fe80::eac5:7aff:fe7d:5332, eth2
L2 11:1:1:1:3:1::/96 [10]
via fe80::eac5:7aff:fe7d:5332, eth2
C 1000::/64 [10]
via ::, xe16
C 2000::/64 [10]
via ::, xe20
R3#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
E 11:1:1:1:1:1::/96 [0]
via ::
E 11:1:1:1:2:1::/96 [0]
via ::
E 11:1:1:1:3:1::/96 [0]
via ::
L2 1000::/64 [20]
via fe80::eac5:7aff:fe6b:7332, eth2
C 2000::/64 [10]
via ::, eth2
R1# show isis database verbose
Tag ABC: 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 0x4755 686 0/0/0
Area Address: 49.0001
NLPID: 0x8E
IPv6 Address: 1000::1
Metric: 10 IS 0000.0000.0002.01
Metric: 10 IPv6 1000::/64
0000.0000.0002.00-00 0x00000004 0x4A36 713 0/0/0
Area Address: 49.0001
NLPID: 0x8E
IPv6 Address: 1000::2
Metric: 10 IS 0000.0000.0002.01
Metric: 10 IPv6 1000::/64
Metric: 10 IPv6-Interarea 2000::/64
Metric: 58 IPv6-Interarea 11:1:1:1::/64
0000.0000.0002.01-00 0x00000001 0x0ECB 685 0/0/0
Metric: 0 IS 0000.0000.0002.00
Metric: 0 IS 0000.0000.0001.00
R2#show isis database verbose
Tag ABC: 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 0x4755 657 0/0/0
Area Address: 49.0001
NLPID: 0x8E
IPv6 Address: 1000::1
Metric: 10 IS 0000.0000.0002.01
Metric: 10 IPv6 1000::/64
0000.0000.0002.00-00* 0x00000004 0x4A36 686 0/0/0
Area Address: 49.0001
NLPID: 0x8E
IPv6 Address: 1000::2
Metric: 10 IS 0000.0000.0002.01
Metric: 10 IPv6 1000::/64
Metric: 10 IPv6-Interarea 2000::/64
Metric: 58 IPv6-Interarea 11:1:1:1::/64
0000.0000.0002.01-00* 0x00000001 0x0ECB 658 0/0/0
Metric: 0 IS 0000.0000.0002.00
Metric: 0 IS 0000.0000.0001.00
IS-IS Level-2 Link State Database:
LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/OL
0000.0000.0002.00-00* 0x00000004 0x67A6 676 0/0/0
Area Address: 49.0001
NLPID: 0x8E
IPv6 Address: 2000::1
Metric: 10 IS 0000.0000.0003.01
Metric: 10 IPv6 2000::/64
Metric: 10 IPv6 1000::/64
0000.0000.0003.00-00 0x00000002 0xC118 675 0/0/0
Area Address: 49.0001
NLPID: 0x8E
IPv6 Address: 2000::2
Metric: 10 IS 0000.0000.0003.01
Metric: 10 IPv6 2000::/64
Metric: 0 IPv6 11:1:1:1:1:1::/96
Metric: 0 IPv6 11:1:1:1:2:1::/96
Metric: 0 IPv6 11:1:1:1:3:1::/96
0000.0000.0003.01-00 0x00000001 0x2DA9 671 0/0/0
Metric: 0 IS 0000.0000.0003.00
Metric: 0 IS 0000.0000.0002.00
R3#show isis database verbose
Tag ABC: VRF : default
IS-IS Level-2 Link State Database:
LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/OL
0000.0000.0002.00-00 0x00000004 0x67A6 605 0/0/0
Area Address: 49.0001
NLPID: 0x8E
IPv6 Address: 2000::1
Metric: 10 IS 0000.0000.0003.01
Metric: 10 IPv6 2000::/64
Metric: 10 IPv6 1000::/64
0000.0000.0003.00-00* 0x00000002 0xC118 606 0/0/0
Area Address: 49.0001
NLPID: 0x8E
IPv6 Address: 2000::2
Metric: 10 IS 0000.0000.0003.01
Metric: 10 IPv6 2000::/64
Metric: 0 IPv6 11:1:1:1:1:1::/96
Metric: 0 IPv6 11:1:1:1:2:1::/96
Metric: 0 IPv6 11:1:1:1:3:1::/96
0000.0000.0003.01-00* 0x00000001 0x2DA9 602 0/0/0
Metric: 0 IS 0000.0000.0003.00
Metric: 0 IS 0000.0000.0002.00
Last modified date: 10/16/2023