Removing Network from EIGRP

[mahesh18]

Hi Everyone,

I need to do some cleanup work on Core switch.

It has different EIGRP AS running on it say like 150,550, 770.

router eigrp 770
  network 172.20.0.0
 network 172.24.0.0
 network 172.30.0.0
 network 172.31.0.0
 network 192.168.20.0
 network 192.168.125.0
 network 192.168.128.0
 network 192.168.220.0
 network 192.168.230.0

when i do sh ip int brief on this switch

i do not see any interface starting with IP 172.24.x.x           and     192.168.20.x

                                                                                                        192.168.125.x

                                                                                                         192.168.128.x

so i can confirm this switch is not advertising these networks to nei switch right?

Is it safe to remove those network commands from the EIGRP 770?

Regards

Mahesh

[Reza Sharifi]

Hi Mahesh,

AS 770 is advertising:

network 192.168.20.0
network 192.168.125.0
network 192.168.128.0

which correspond to the IP address of the interfaces you posted.

If this is production and AS 770 is peering than you should not remove it.

HTH

Reza

[mahesh18]

Hi Reza,

This is production switch.

There is no interface on this switch which starts with below IPs

192.168.20.x

192.168.125.x

192.168.128.x

So does it mean this switch is not advertising the above networks?

Regards

MAhesh

[Reza Sharifi · Accepted solution]

Hi Mahesh,

That is correct.  If there is no interface with these IP than they can be removed. Please be careful to double and triple check before doing it.  You don't want to cause an outage.

Good Luck

Reza

[mahesh18]

Thanks for confirming my thoughts will double check as i don't want to break the network.

Regards

MAhesh

[Reza Sharifi]

Sorry Mahesh and Rick,

Now I know what I was thinking to reference these IP to Interfaces.  The way the IPs are lined up (top to bottom), I thought that is the output of "sh ip int brie" :).

Reza

[Richard Burts · Accepted solution]

Reza

I wonder if you read a bit too quickly (or whether you see something that I missed). I do not see any reference to interfaces with addresses of 192.168.20.0 or 192.168.125.0 or 192.168.128.0.

I only see EIGRP network statements referencing those addresses.

Mahesh

I find it a fairly common error in configuring EIGRP where someone includes network statements for all the networks that they expect EIGRP to advertise. Your question is correct in that you do not need network statements  for all networks to advertise but only for the networks that are locally connected and which you want EIGRP to initiate advertisements for. So if those prefixes do not represent networks/subnets that are locally connected then you may safely remove those network statements.

HTH

Rick

[mahesh18]

Many thanks Rick.

It is always good to get your confirmation.

Regards

MAhesh

[Richard Burts]

Reza

I must admit that the layout of that data did suggest that it was command output and that my first reaction was to understand it that way. But then I realized that it was not really command output.

Mahesh

I would like to address the follow up question that you asked "So does it mean this switch is not advertising the above networks?"  This question sort of reflects the point that I tried to make in an earlier post that some people think that you need network statements for all the networks that you want the routing protocol to advertise. You do not necessarily need a network statement for the routing protocol to advertise the network. You only need the network statement if the router is to initiate the advertisement.

Perhaps another way to make the point is to say that the routing protocol will advertise networks that it know about. And that the routing protocol may know a network because it has a network statement for it and that the routing protocol also may know a network because a neighbor advertised it to the router.

So if EIGRP knows networks 192.168.20.x, 192.168.125.x, and 192.168.128.x from a neighbor advertisement then EIGRP will advertise those networks without needing a network statement for them.

HTH

Rick