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

nyl20081224
Level 1
Level 1

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?

6 Replies 6

Giuseppe Larosa
Hall of Fame
Hall of Fame

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

Giuseppe

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

regards

shivlu jain

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

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
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México

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

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México

nyl20081224
Level 1
Level 1

my configration is completely

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