EIGRP & directly connected networks

[r.koehne]

Hi, I hope someone can solve my problem.

I have an EIGRP topology and want a directly connected network on some edge routers not in the routing table. Because of older release the network-command is classfull (no mask option available) and the network is in the topology-table as "redistributed via connected". I configured the interface as "passive", "no redistribute connected" is the default and also "redistribute connected" with an appropriate filter does not prevent EIGRP to redistribute that network. Any idea ??

THANKS !!!

[millerv]

Could you post the Eigrp routing statements?

[millerv]

take a look at this, the reference is off the cisco CD

http://127.0.0.1:8080/cc/td/doc/product/software/ios121/121cgcr/ip_c/ipcprt2/1cdindep.htm#xtocid2568613

[r.koehne]

interface ethernet 0/0

ip address 148.198.48.1 255.255.255.0

!

interface ethernet 0/1

ip address 148.198.49.1 255.255.255.0

!

interface serial 1/0

ip address 148.198.54.1 255.255.255.252

!

router eigrp 1

redistribute connected 100000 1 255 1 1500 route-map no_eigrp

passive-interface ethernet 0/1

network 148.198.0.0

no auto-summary

!

route-map no_eigrp permit 10

match ip address prefix-list no-eigrp

!

ip prefix-list no-eigrp seq 5 deny 148.198.49.0/24

ip prefix-list no-eigrp seq 10 permit 148.198.0.0/16 le 32

[millerv]

heres some stuff

Description of EIGRP Redistribution Defect CSCdj28874

When a network is included in the EIGRP routing process because it is specified with the network x.x.x.x command and that same network is redistributed into EIGRP via the redistribute connected command, there will be two entries for the network in the EIGRP topology table.

If the interface connecting that network goes down, only one of the two entries will be removed from the topology table. The entry learned via redistribution will remain in the topology table and be advertised, even though it is no longer valid.

If the connected subnet is part of your major net, why redistribute?

[r.koehne]

Normally I would guess that the directly connected networks are not in the topology table, because "no redistribute connected" should be the

default. But they are. Entering the command has no effect. The network of ethernet 0/1 is as "redistributed via connected" in my topology table. Therefore I tried redistribution plus filter as workaround for filtering the network I want out of the table. But also this workaround has no effect.

I can find no way to remove this network from my topology table.

A distribution-list I can´t use for some reasons. I must get the network out of the topology table on the router where it is directly connected (when possible ??).

[millerv]

have you considered using a distribute list ?

I was going thru some notes for ccie lab, and one author says that for routing updates if onoe of the rout map statements match, the update gets dropped.

[r.koehne]

I can prevent the network from being advertised with a distribute-list and in most cases this might be the solution. But not always. Therefore the question is, why I can´t remove the directly connected network from the topology table. Maybe that´s how Cisco implemented EIGRP. I could find no hints. According to my understanding, only the subnets required should be in the topology table and as a result advertised without filtering.

[millerv]

Ronald, I think you are correct in suggesting that

EIGRP will not remove the directly connected nets,

but with the distribute list will keep the advertisement from being propagated. Would it be possible for you to open a case with the TAC on this one ? I for one would be interested in the answer.

regards

vm

[r.koehne]

Hi Vince,

according to the TAC-engineer I answered the question by myself.

Because of the major network number in the network statement the IOS by default understands that all the subnets covered by that network would have to be advertised. Therefore all those routes are included in the topology table.

The topology table must contain all possible routes to all known networks. So the only way is to filter what is sent to the neighbors by distribute lists.

To have better granularity, specific interface can be configured in later IOS releases.

Regards

Ronald

[millerv]

Thanks Ronald.