07-17-2006 07:54 AM - edited 03-03-2019 01:21 PM
Greetings everyone,
During a cut this weekend I wanted to aggregate our class C advertisements.
The original config was
router bgp 12345
network xx.yy.zz.0
network xx.yy.za.0
The new config was
router bgp 12345
network xx.yy.zz.0/23
My reasoning was that this syntax would advertise both of our class C's. However, when the BGP session established, while I received all external routes from the upstream peer the peer received none from me. On further examination my router was not sending updates. If I returned to the original....ie not forcing a mask...it worked. So my question is, do you have to "define" the network first before either aggregating or splitting A's, B's, or C's, or is there something else I'm missing? I would also like to advertise only 3/4 of our Class B as well but had the same issues.
Thanks,
Greg
Solved! Go to Solution.
07-17-2006 08:38 AM
Hi Greg,
When u use n/w command, it will look for exact prefix in routing table until autosummary is disabled. So first u chk ur own bgp table whether the roots that u expected are there or not???
Rgs,
07-17-2006 10:15 AM
Greg
I would suggest that you put in statics that match the prefix and mask that you want to advertise. It will work better that way.
HTH
Rick
07-17-2006 07:58 AM
Hello,
this is quite simple
keep the first 2 networks and add
aggregate-address xx.yy.zz.0 255.255.254.0 summary-only
Vlad
07-17-2006 08:17 AM
Vlad,
Thanks.....what about splitting though, ie I want to take a class B and only advertise 3/4 of it? I tried
network 123.456.0.0/17
network 123.456.128.0/18
but had the same advertisement issues (ie my router did not update the peer).
Thanks again,
Greg
07-17-2006 08:38 AM
Hi Greg,
When u use n/w command, it will look for exact prefix in routing table until autosummary is disabled. So first u chk ur own bgp table whether the roots that u expected are there or not???
Rgs,
07-17-2006 10:12 AM
Hi,
Ooh, that's making sense. The router has a static which points the entire class B to the next internal hop. So, is the best idea to turn off auto summary or replace those statics with *exactly* the same routes I want to advertise?
Thanks again,
Greg
07-17-2006 10:15 AM
Greg
I would suggest that you put in statics that match the prefix and mask that you want to advertise. It will work better that way.
HTH
Rick
07-17-2006 10:25 AM
Hi Greg,
Even u can have a static route pointing to null0 provided if u own the whole subnet u r advertising.....
Rgs,
07-17-2006 10:42 AM
Thank you everyone for your replies, it really helped. I will try the statics.
Thanks again,
Greg Schaffer
Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community: