mpls vpn rr-group question(7)(question)

[nyl20081224]

question:

at r1,r2 rr-group both deny rt 1:5.

"ip extcommunity-list 1 deny rt 1:5"

why can r5 learned route of r8??

and why can r5 can ping r8?

[Giuseppe Larosa]

ello Wang,

the config files that you have tried to attach are not complete.

However, notice that a vpnv4 router can have mutiple RT attached to it.

So you need to verify if the route you see on R5 have multiple RTs

in that case you can have the answer.

to have an exact match that says if one of the RTs is xx:yy deny the route you should use extended extcommunity list

Hope to help

Giuseppe

[shivlu jain]

Giuseppe

Does cisco support more than 30 rt values attached in bgp update route?

regards

shivlu jain

[Giuseppe Larosa]

Hello Shivlu,

according to RFC

http://www.ietf.org/rfc/rfc2858.txt

there is a byte wide field for the number of SNPAs (note I don't see any reference to route target here it is very general)

and a byte wide field to say how many bytes form a SNPA.

So it looks like possible to associate 30 RTs to a vpnv4 prefix but be aware that memory usage can grow very quicky.

see also

http://www.ietf.org/IESG/Implementations/mp-bgp-implementation-report.txt

this is not very new but provides info about different vendors implementations of MP-BGP.

But this is theory and implementation may put some limit to the number of RTs

Hope to help

Giuseppe

[Harold Ritter]

Giuseppe,

IOS would allow you to have up to 128 RT extended communities in one BGP update message. Bear in mind that the maximum BGP message size being 4096, it would not leave you much space for anything other than the extended communities.

Regards

[Harold Ritter]

Giuseppe,

Sorry, 128 is actually the old limitation. I just checked and the latest 12.0S code would allow in excess of 500 RT extended communities. I don't know if anyone would like to go that far though.

Regards

[nyl20081224]

my configration is completely