Summarisation issue.

[rawatmohinder]

I have attached a topology diagram...

So i want to know about summarisation command in following protocols..

1.) if we take the case of eigrp.. if i give no summarisation command on TK1 and TK2 then the actual route will go to TK3. what will happen to route when it will go through TK3 to TK4.

will it be 10.0.0.0/8

or will be actual routes.

10.1.1.0/24 and 10.0.2.0/24

so is there any need of giving no auto-summary on TK3 router.. if we want to send actual subnet to TK4.

2.) what will happen in case of RIP,EIGRP and OSPF..

Thanks

Mahi

[pkhatri]

Mahi,

That is a very good question...

1. The routes advertised by TK3 to TK4 will be the actual routes, not the summary. The 'auto-summary' command has no effect in this case. However, if TK3 had a directly connected interface in network 10.0.0.0/8 AND had a 'network 10.0.0.0' command in EIGRP AND auto-summary was enabled, the routes would have been summarised. But that is not the case here so you need to do nothing with the auto-summary command on TK3. I have tested this scenario previously.

2. OSPF has no auto-summarisation. I have not tested this precise scenario specifically with RIPv2 but I would imagine that it would be the same.

Pls do remember to rate posts.

Paresh

[rawatmohinder]

Hi Paresh,

Thanks a lot..

i will also check it out in the lab.

Thanks

Mahi

[pkhatri]

No probs, Mahi.

Pls do take the effort to rate the post if you found it useful

Paresh

[bhedlund]

Paresh is absolutely correct. The only way TK3 would send a 10.0.0.0/8 summary to TK4 would be if it was manually configured to do so on the interface to TK4.

'ip summary-address eigrp 100 10.0.0.0 255.0.0.0'