Note - Before this Scenario you should read Question 30 To Question 35 in previous Chapter RIP - INTERVIEW QUESTIONS and Chapter RIP - OFFSET LISTS CONFIGURATION
Maximum Hop Count Issue
Figure - 1
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.
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. Everything is OK, same version, no passive interface.
Let's check if the network is in the RIP database of R2.
R2#Show ip rip database
10.0.0.0/8 auto-summary
10.0.0.0/8
[1] via 192.168.20.1, 00:00:22, 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
It's in the RIP database.
Now it's time to enable debug on R1
RIP protocol debugging is on
RIP: received v2 update from 192.168.20.2 on FastEthernet0/0
172.16.0.0/24 via 0.0.0.0 in 16 hops (inaccessible)
R1 does receive an update but network 172.16.0.0/24 has hop count 16. This cannot be installed in the routing table. in large network this problem might be occur but for this scenario I used an offset list
R2(config)#router rip
R2(config-router)#no offset-list 0 out 15
this should fix the problem:
RIP protocol debugging is on
RIP: received v2 update from 192.168.20.2 on FastEthernet0/0
172.16.0.0/24 via 0.0.0.0 in 1 hops
R1 now shows a hop count of 1, this can be installed
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 always remember a hop count of 16 is unreachable for RIP, if the network is small, check for offset-list that increased the metric..
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.
0 comments:
Post a Comment
If you like my posts then please comment and if you don’t like then please suggest me to improve, and if you have any query related to post then please text me through the comment box or mail me on upadhyayambition@gmail.com , I will try my best to solve your queries as soon as possible.