RIPv2 Manual Summarization

The output on R8   shows a metric of 1 for R1's lo0 150.1.1.1, but a metric of 4 for R9;s lo0

 

here is snapshot of the configs

R5's interface e0/0.58  towards R8

R5#sh run int e0/0.58

Building configuration...

Current configuration : 127 bytes

interface Ethernet0/0.58

 encapsulation dot1Q 58

 ip address 155.1.58.5 255.255.255.0

 ipv6 address 2001:155:1:58::5/64

end

==== and with summarization we have:


R5#sh run int e0/0.58

Building configuration...

Current configuration : 175 bytes

interface Ethernet0/0.58

 encapsulation dot1Q 58

 ip address 155.1.58.5 255.255.255.0

 ip summary-address rip 150.1.0.0 255.255.248.0

 ipv6 address 2001:155:1:58::5/64

end

=================== here are the routes on R8 before summary on R5


R8#sh ip route 150.1.0.0 long


Gateway of last resort is not set

      150.1.0.0/32 is subnetted, 10 subnets

R        150.1.1.1 [120/2] via 155.1.58.5, 00:00:05, Ethernet0/0.58

R        150.1.2.2 [120/2] via 155.1.58.5, 00:00:05, Ethernet0/0.58

R        150.1.3.3 [120/2] via 155.1.58.5, 00:00:05, Ethernet0/0.58

R        150.1.4.4 [120/2] via 155.1.58.5, 00:00:05, Ethernet0/0.58

R        150.1.5.5 [120/1] via 155.1.58.5, 00:00:05, Ethernet0/0.58

R        150.1.6.6 [120/3] via 155.1.58.5, 00:00:05, Ethernet0/0.58

R        150.1.7.7 [120/3] via 155.1.58.5, 00:00:05, Ethernet0/0.58

C        150.1.8.8 is directly connected, Loopback0

R        150.1.9.9 [120/4] via 155.1.58.5, 00:00:05, Ethernet0/0.58

R        150.1.10.10 [120/1] via 155.1.108.10, 00:00:09, Ethernet0/0.108

and after the summary on R5, R8 shows this:

R8#sh ip route 150.1.0.0 long


Gateway of last resort is not set


      150.1.0.0/16 is variably subnetted, 4 subnets, 2 masks

R        150.1.0.0/21 [120/1] via 155.1.58.5, 00:00:15, Ethernet0/0.58

C        150.1.8.8/32 is directly connected, Loopback0

R        150.1.9.9/32 [120/4] via 155.1.58.5, 00:00:15, Ethernet0/0.58

R        150.1.10.10/32 [120/1] via 155.1.108.10, 00:00:11, Ethernet0/0.108


Why is the metric of R1's lo0 is 1, but the metric of R9's lo0 is 4



R8#sh ip route 150.1.1.1

Routing entry for 150.1.0.0/21

  Known via "rip", distance 120, metric 1

  Redistributing via rip

  Last update from 155.1.58.5 on Ethernet0/0.58, 00:00:04 ago

  Routing Descriptor Blocks:

  * 155.1.58.5, from 155.1.58.5, 00:00:04 ago, via Ethernet0/0.58

      Route metric is 1, traffic share count is 1


and for R9's lo0


R8#sh ip route 150.1.9.9

Routing entry for 150.1.9.9/32

  Known via "rip", distance 120, metric 4

  Redistributing via rip

  Last update from 155.1.58.5 on Ethernet0/0.58, 00:00:15 ago

  Routing Descriptor Blocks:

  * 155.1.58.5, from 155.1.58.5, 00:00:15 ago, via Ethernet0/0.58

      Route metric is 4, traffic share count is 1

R8#








Comments

  • 150.1.9.9/32 is not part of 150.1.0.0/21.

  • Thanks  bengood24,

    but the questio nis about the metric of 1 versus metric of 4.

    ip summary-address rip ...... on R5, makes the metric equl to 1 for the summurized routes as they are sent downstream to R8, and keeps the original metric of 4 for the routes that were not part of the summary.

    I clearly underdsant the 150.1.9.9 is not part of the summary 150.1.0.0/21 

     

  • JoeMJoeM ✭✭✭

    Without having the lab up, just using your output, my guess is that the metric is 3 on R5.  As noted, the summary doesn't change the metric for this specific route.

    Do a traceroute from R8. What are the 4 hops?

  • Good Day Sir,

        The way that I would look at this is that since the 150.1.9.9/32 route does not fall under your summarization route of 150.1.0.0/21 that route will be advertised normally. Since that route is 4 hops away that is what will be advertised.

    Respectfully,

    AntRal

     

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