RIP: Filtering based on Source

RIP: Filtering based on Source

 

·         We can filter the routes based on the source

 

·         Let me take a small topology to configure filtering based on source in RIP

 

R1------S1/0-------------s1/0----R2----s1/1--------------s1/1------R3

 

10.1.12.1--------------10.1.12.2-----11.1.23.2--------------11.1.23.3

 

R1(config-router)#do show run | sec router

router rip

 version 2

 network 1.0.0.0

 network 10.0.0.0

 no auto-summary

R1(config-router)#

 

R2(config-router)#do show run | sec router

router rip

 version 2

 network 2.0.0.0

 network 10.0.0.0

 no auto-summary

R2(config-router)#

 

R1(config-router)#do show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2

       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

       ia - IS-IS inter area, * - candidate default, U - per-user static route

       o - ODR, P - periodic downloaded static route

 

Gateway of last resort is not set

 

     1.0.0.0/32 is subnetted, 1 subnets

C       1.1.1.1 is directly connected, Loopback0

     2.0.0.0/32 is subnetted, 1 subnets

R       2.2.2.2 [120/1] via 10.1.12.2, 00:00:26, Serial1/0

     10.0.0.0/24 is subnetted, 1 subnets

C       10.1.12.0 is directly connected, Serial1/0

R1(config-router)#

 

R2(config-router)#do show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2

       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

       ia - IS-IS inter area, * - candidate default, U - per-user static route

       o - ODR, P - periodic downloaded static route

 

Gateway of last resort is not set

 

     1.0.0.0/32 is subnetted, 1 subnets

R       1.1.1.1 [120/1] via 10.1.12.1, 00:00:26, Serial1/0

     2.0.0.0/32 is subnetted, 1 subnets

C       2.2.2.2 is directly connected, Loopback0

     10.0.0.0/24 is subnetted, 1 subnets

C       10.1.12.0 is directly connected, Serial1/0

     11.0.0.0/24 is subnetted, 1 subnets

C       11.1.23.0 is directly connected, Serial1/1

R2(config-router)#

 

Observation:

·         RIP is configured between R1 and R2

·         R1 has advertised its loopback0 1.1.1.1/32 into RIP

·         R2 has advertised its loopback0 2.2.2.2/32 into RIP

 

R1#show ip protocols

Routing Protocol is "rip"

  Outgoing update filter list for all interfaces is not set

  Incoming update filter list for all interfaces is not set

  Sending updates every 30 seconds, next due in 17 seconds

  Invalid after 180 seconds, hold down 180, flushed after 240

  Redistributing: rip

  Default version control: send version 2, receive version 2

    Interface             Send  Recv  Triggered RIP  Key-chain

    Serial1/0             2     2

    Loopback0             2     2

  Automatic network summarization is not in effect

  Maximum path: 4

  Routing for Networks:

    1.0.0.0

    10.0.0.0

  Routing Information Sources:

    Gateway         Distance      Last Update

    10.1.12.2            120      00:00:06

  Distance: (default is 120)

 

R1#

 

R2#show ip protocols

Routing Protocol is "rip"

  Outgoing update filter list for all interfaces is not set

  Incoming update filter list for all interfaces is not set

  Sending updates every 30 seconds, next due in 17 seconds

  Invalid after 180 seconds, hold down 180, flushed after 240

  Redistributing: rip

  Default version control: send version 2, receive version 2

    Interface             Send  Recv  Triggered RIP  Key-chain

    Serial1/0             2     2

    Loopback0             2     2

  Automatic network summarization is not in effect

    Interface             Send  Recv  Triggered RIP  Key-chain

  Maximum path: 4

  Routing for Networks:

    2.0.0.0

    10.0.0.0

  Routing Information Sources:

    Gateway         Distance      Last Update

    10.1.12.1            120      00:00:03

  Distance: (default is 120)

 

R2#

 

Observation:

·         In R1, source Gateway is displayed as 10.1.12.2

·         In R2, source Gateway is displayed as 10.1.12.1

·         If R1 doesn’t want to receive any updates from R2, we can filter the routes based on the Source Gateway

 

·         Let me configure to filter the routes from R2 in R1:

 

R1(config)#ip prefix-list 1 seq 5 permit 10.1.12.2/24

R1(config)#router rip

R1(config-router)#distribute-list gateway 1 in

 

R1(config)#do show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2

       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

       ia - IS-IS inter area, * - candidate default, U - per-user static route

       o - ODR, P - periodic downloaded static route

 

Gateway of last resort is not set

 

     1.0.0.0/32 is subnetted, 1 subnets

C       1.1.1.1 is directly connected, Loopback0

     10.0.0.0/24 is subnetted, 1 subnets

C       10.1.12.0 is directly connected, Serial1/0

R1(config)#

 

Observation:

·         R1 doesn’t have any routes from R2 now