Using passive interface on RIP only does 1 thing (stop sending RIP updates out of interface) but will not stop advertising the subnetwork on the interface to peer neighbors
Ex On R2 enabling passive interface on S0/0
R2(config)#router rip
R2(config-router)#passive-interface s0/0
If you check on R1 now you'll see that 2.2.2.2 is no longer learnt from R2
R1#sh ip route 2.2.2.2
Routing entry for 2.2.2.2/32
Known via "rip", distance 120, metric 3
Redistributing via rip
Last update from 192.168.13.3 on Serial0/1, 00:00:20 ago
Routing Descriptor Blocks:
* 192.168.13.3, from 192.168.13.3, 00:00:20 ago, via Serial0/1 <<<<<<< R3
Route metric is 3, traffic share count is 1
Ex2: Enabling passive interface on loopback interface , long ago i used to believe would stop router processor from sending the RIP update about this network but turned out I'm wrong
R2(config)#router rip
R2(config-router)#passive-interface lo0
R4#sh ip route 2.2.2.2
Routing entry for 2.2.2.2/32
Known via "rip", distance 120, metric 1
Redistributing via rip
Last update from 192.168.24.2 on Serial0/1, 00:00:22 ago
Routing Descriptor Blocks:
* 192.168.24.2, from 192.168.24.2, 00:00:22 ago, via Serial0/1 <<<<< Still R4 learns about it
Route metric is 1, traffic share count is 1
So seems to do filtering we can use route-filtering but not passive interface :(
Summerization in Ripv2 is made using interface level configuration.
There are 2 notes that i want to point out down there , first while doing this lab i actually made a loop
second i want to point out to one limitation in RIPv2 concerning summerization
Task 1 : Summerize 2.0.0.0/8 out of R2 to R1 instead of 2.2.2.2/32
R2(config-if)#ip summary-address rip 2.0.0.0 255.0.0.0
Looks beautiful but now take another look at our topology ? don't you notice a problem , the problem is that the summary route kept appearing and disappearing from R1 so i made a debug ip rip database and noticed the below
*Mar 1 00:42:49.187: RIP-DB: Remove 2.0.0.0/8, (metric 4294967295) via 192.168.12.2, Serial0/0
What happened is the following R2 advertise to R1 2.0.0.0/8 so R1 advertise it to R3 then R4 and R4 then advertise it back to R2 from R2 momentery
R 2.0.0.0/8 [120/4] via 192.168.24.4, 00:00:00, Serial0/1
Note* that R2 don't install summary entry once summerization is configured and seems that this is what cause the problem
Solution Make R2 summarize out of all interfaces not only S0/0 but also through S0/1 to avoid loop
Task 2 : Summarize network 192.168.0.0/16 out of S0/0
R2(config-if)#ip summary-address r 192.168.0.0 255.255.0.0
Summary mask must be greater or equal to major net
It turned out that RIP doesn't support superneting so i can't advertise a summary address of a super net like 192.168.0.0 since it's by default a class C of /24
The only solution to fix issue would be create a null 0 route and resdistribute it into RIP
R2(config)# ip route 192.168.0.0 255.255.0.0 null 0
R2(config)# router rip
R2(config-router)# redistribute static
R1#sh ip route | i /16
R 192.168.0.0/16 [120/1] via 192.168.12.2, 00:00:04, Serial0/0
When RIP v2 authentication is enabled on 1 router it means it'll authenticate the updates coming from peer and not the updates being sent to peer.
Example here enabling authentication only on R2
R2#sh run int s0/0
Building configuration...
Current configuration : 193 bytes
!
interface Serial0/0
ip address 192.168.12.2 255.255.255.0
ip rip authentication mode md5
ip rip authentication key-chain cisco
Results of debug
*Mar 1 00:10:26.535: RIP: ignored v2 packet from 192.168.12.1 (invalid authentication)
But if we check routing table on R1 and R2
R1#sh ip route 2.2.2.2
Routing entry for 2.2.2.2/32
Known via "rip", distance 120, metric 1
Redistributing via rip
Last update from 192.168.12.2 on Serial0/0, 00:00:01 ago
Routing Descriptor Blocks:
* 192.168.12.2, from 192.168.12.2, 00:00:01 ago, via Serial0/0
Route metric is 1, traffic share count is 1
Router 1 still learns about routes from R2
But router 2 doesn't learn any routes from R1
R2#sh ip route 1.1.1.1
Routing entry for 1.1.1.1/32
Known via "rip", distance 120, metric 3
Redistributing via rip
Last update from 192.168.24.4 on Serial0/1, 00:00:21 ago
Routing Descriptor Blocks:
* 192.168.24.4, from 192.168.24.4, 00:00:21 ago, via Serial0/1 <<<<<<< From R4
Route metric is 3, traffic share count is 1
RSS Feed