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Pradeep H A
Beginner

RIP Routing information sources

Hi All,

I am studying the routing protocol concepts. Came across this router running rip in one of our client networks The setup is as shown in the below pic

1R - RIP updates.JPG

R1#sh run | section router rip

router rip

version 2

redistribute bgp 64515 metric 1 route-map bgp_to_rip

network 192.168.77.0

distribute-list 14 in GigabitEthernet0/0

distribute-list 15 out GigabitEthernet0/0

R1#sh ip protocols

*** IP Routing is NSF aware ***

-----------------------------------------------------------

BGP Output removed

-----------------------------------------------------------

Routing Protocol is "rip"

Outgoing update filter list for all interfaces is not set

  GigabitEthernet0/0 filtered by 15 (per-user), default is not set

Incoming update filter list for all interfaces is not set

  GigabitEthernet0/0 filtered by 14 (per-user), default is not set

Sending updates every 30 seconds, next due in 12 seconds

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

Redistributing: bgp 64515, rip

Default version control: send version 2, receive version 2

  Interface            Send Recv Triggered RIP Key-chain

  GigabitEthernet0/0  2    2

Automatic network summarization is in effect

Maximum path: 4

Routing for Networks:

  192.168.77.0

Routing Information Sources:

  Gateway        Distance    Last Update

  192.168.77.3        120    00:00:14

  192.168.77.2        120    00:00:13

  192.168.77.17      120    00:00:16

Distance: (default is 120)

R1#sh ip rip database 192.168.92.0 255.255.255.0

192.168.92.0/24

  [1] via 192.168.77.8, from 192.168.77.3, 00:00:06, GigabitEthernet0/0

R1#sh ip rip database 192.168.23.0 255.255.255.0

192.168.23.0/24

  [3] via 192.168.77.2, 00:00:30, GigabitEthernet0/0

In the R1's routing table some RIP routes are pointing to 192.168.77.8 as next hop, does that mean R1 is recieving RIP updates from 192.168.77.8?

If yes then why isnt 192.168.77.8 listed under "Routing information sources" in Show ip protocols output?

and what does "Via" & "From" mean in the below output?

R1#sh ip rip database 192.168.92.0 255.255.255.0

192.168.92.0/24

  [1] via 192.168.77.8, from 192.168.77.3, 00:00:06, GigabitEthernet0/0

R1#sh ip rip database 192.168.23.0 255.255.255.0

192.168.23.0/24

  [3] via 192.168.77.2, 00:00:30, GigabitEthernet0/0

Any kind of help will be much appreciated.

Thanks a lot in advance!

1 ACCEPTED SOLUTION

Accepted Solutions

Hello Pradeep,

yes I agree.

Router with IP address 192.168.77.3 is probably redistributing a static route with destination 192.168.92.0 and IP next-hop 192.168.77.8 or the route is learned from another routing protocol running on both 192.168.77.3 and 192.168.77.8 and redistributed into RIP by 192.168.77.3

Hope to help

Giuseppe

View solution in original post

3 REPLIES 3
Giuseppe Larosa
Hall of Fame Master

Hello Pradeep,

I would say that  this is an example of third party next-hop:

R1#sh ip rip database 192.168.92.0 255.255.255.0

192.168.92.0/24

  [1] via 192.168.77.8, from 192.168.77.3, 00:00:06, GigabitEthernet0/0

192.168.77.8 is not speaking RIP or it would be a RIP neighbor, however the router with LAN IP address 192.168.77.3 has learned  the route to 192.168.92.0 via 192.168.77.8, and it advertises the route with an IP next-hop = 192.168.77.8, so that other routers in the same LAN can send traffic directly to 192.168.77.8, instead of having the first packet sent to 192.168.77.3 and then having this router to send an ICMP redirect back telling that a better next-hop exists in the same IP subnet.

The presence of an IP next-hop field in the  RIP route data structure allows for this

Edit:

so via indicates the effective IP next-hop of the route and from indicates the route information source = the RIP neighbor from which the route has been received.

Hope to help

Giuseppe

Hi Giuseppe,

That really helped a lot....

But one little doubt..

Though 192.168.77.8 is not showing as RIP neighbor, 192.168.77.3 is advertising the next hop for 192.168.92.0/24 network as 192.168.77.8.

Is this due some sort of redistribution configured on 192.168.77.3? or what makes it do that?

Thanks again! You rock!

Hello Pradeep,

yes I agree.

Router with IP address 192.168.77.3 is probably redistributing a static route with destination 192.168.92.0 and IP next-hop 192.168.77.8 or the route is learned from another routing protocol running on both 192.168.77.3 and 192.168.77.8 and redistributed into RIP by 192.168.77.3

Hope to help

Giuseppe

View solution in original post