Interface Issue
Figure - 1
Note - This is packet tracer diagram so you can easily understand by red light indication, here is interface F0/1 on R2 router is administratively down, but in real life you will have to follow below troubleshooting command and process to resolve this issue.
Just like previous example. In Figure - 1 I am going to use these two router R1 and R2. I have configured on both RIPv2, According to Figure-1 R1 is supposed to learn about 172.16.0.0/24 but look at the output there is no 172.16.0.0/24 .
R1#sh ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
i - IS-IS, 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
10.0.0.0/24 is subnetted, 1 subnets
C 10.1.1.0 is directly connected, FastEthernet0/1
C 192.168.20.0/24 is directly connected, FastEthernet0/0
If you will notice in above output then you will find two directly connected route, 192.168.20.0 for R2 router and 10.1.1.0 for PC1, but there is no any RIP route with network 172.16.10.0 for PC2.
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
i - IS-IS, 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
10.0.0.0/24 is subnetted, 1 subnets
C 10.1.1.0 is directly connected, FastEthernet0/1
C 192.168.20.0/24 is directly connected, FastEthernet0/0
If you will notice in above output then you will find two directly connected route, 192.168.20.0 for R2 router and 10.1.1.0 for PC1, but there is no any RIP route with network 172.16.10.0 for PC2.
Note ;- You can also use Show ip route rip command to check this, Show ip route rip command only display the RIP route information.
So now let's check what is problem
R1#Show ip protocol
Routing Protocol is "rip"
Sending updates every 30 seconds, next due in 4 seconds
Invalid after 180 seconds, hold down 180, flushed after 240
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Redistributing: rip
Default version control: send version 2, receive 2
Interface Send Recv Triggered RIP Key-chain
FastEthernet0/1 2 2
Automatic network summarization is in effect
Maximum path: 4
Routing for Networks:
10.0.0.0
192.168.20.0
Passive Interface(s):
Routing Information Sources:
Gateway Distance Last Update
192.168.20.2 120 00:00:55
Distance: (default is 120)
R2#Show ip protocol
Routing Protocol is "rip"
Sending updates every 30 seconds, next due in 22 seconds
Invalid after 180 seconds, hold down 180, flushed after 240
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Redistributing: rip
Default version control: send version 2, receive 2
Interface Send Recv Triggered RIP Key-chain
FastEthernet0/0 2 2
FastEthernet0/1 2 2
Automatic network summarization is in effect
Maximum path: 4
Routing for Networks:
172.16.0.0
192.168.20.0
Passive Interface(s):
Routing Information Sources:
Gateway Distance Last Update
192.168.20.1 120 00:05:01
Distance: (default is 120)
Here is no any issue, correct networks are activated on both router. Let's check R2 since that's the router that is supposed to advertise network 172.16.0.0/24
10.0.0.0/8 auto-summary
10.0.0.0/8
[1] via 192.168.20.1, 00:00:00, FastEthernet0/0
192.168.20.0/24 auto-summary
192.168.20.0/24 directly connected, FastEthernet0/0
Now check
Notice in the above output , 172.16.0.0 network is not in the database, so it cannot be advertise. R2 router have the correct network command so network should be available in the R2 database. So this is an interface related issue.
Let's check that
R2#Show ip int brief
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 192.168.20.2 YES manual up up
FastEthernet0/1 172.16.10.1 YES manual administratively down down
Vlan1 unassigned YES unset administratively down down
Here is the problem -Notice in the above output interface F0/1 of Router R2 is administratively down , on which network 172.16.0.0 configured.
Now Let's fix it,
R2#config t
R2(config)#int f0/1
R2(config-if)#no shutdown
Now check , Take a look at the RIP database of R2 Router
10.0.0.0/8 auto-summary
10.0.0.0/8 [1] via 192.168.20.1, 00:00:04, FastEthernet0/0
172.16.10.0/24 auto-summary
172.16.10.0/24 directly connected, FastEthernet0/1
192.168.20.0/24 auto-summary
192.168.20.0/24 directly connected, FastEthernet0/0
There it is, now it can be advertised R1.
Let's check R1
R1#sh ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
i - IS-IS, 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
10.0.0.0/24 is subnetted, 1 subnets
C 10.1.1.0 is directly connected, FastEthernet0/1
R 172.16.0.0/16 [120/1] via 192.168.20.2, 00:00:25, FastEthernet0/0 .......... SEE THIS
C 192.168.20.0/24 is directly connected, FastEthernet0/0
Now problem has been solved, so make sure your interface is up and running..
Hello and welcome to networktopic Blog. My name is Anubhav. I am a Senior Network Egineer. I have created this blog specially to serve interview questions and answer on Network Routing and Switching, I will try my best to serve correct and updated networking knowledge for you as per my corporate experience.
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