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Cisco ORF/BGP question

  • From: Roger Clark Williams <rogerw@nordlink.com>
  • Date: Fri, 14 Nov 2003 10:37:02 -0500
  • Cc: cgill@gnilink.net
  • Resent-Date: Fri, 14 Nov 2003 11:09:25 -0500
  • To: MPLS-ops Mailing List <mpls-ops@mplsrc.com>
  • X-Sender: rogerw@together.net@207.69.200.25

A BGP/ Outbound Route Filter question for the IOS/BGP cognescenti amongst 
the readers

Assume MPLS VPNs running, Cisco IOS involved, particular routers not important.

Assume  PE1 is supporting 2 VPNs, Green_VPN and Blue_VPN

Also assume on the network as a whole there is a Red_VPN supported by PE2.

It is my understanding that, as part of the MP-BGPv4 functionality, at T0 
(startup) all BGP VPNV4 speakers will issue updates to neighbors about all 
supported VPNs. Therefore PE1 will receive an update concerning the Red_VPN 
from PE2. Since PE1 doesn't need that update, it drops it and sends an ORF 
message to PE2. From that point on PE2 will not send Red_VPN updates to PE1.

The question is this: In what way is this ORF applied within PE2? Does PE2 
now hold two separate versions of the update, one for PE1 and a different 
one for other PEs? Or is the total list built and that particular part of 
the update stripped out of any update sent to PE1?

Specific references would be most welcome. Thanks in advance

Roger Williams

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