VPRN Features
Page 1094 7750 SR OS Services Guide
Figure 137: Option C Example
With Option-C, knowledge from the remote AS is distributed throughout the local AS. This
distribution allows for higher scalability but also requires all PEs and ASBRs involved in the Inter-
AS VPRNs to participate in the exchange of inter-AS routing information.
In Option-C, the ASBRs distribute reachability information for remote PE’s system IP addresses
only. This is done between the ASBRs by exchanging MP-eBGP labeled routes, using RFC 3107,
Carrying Label Information in BGP-4 .
Distribution of VPRN routing information is handled by either direct MP-BGP peering between
PEs in the different ASNs or more likely by one or more route reflectors in ASN.
IP/MPLS
Backbone
ASBR
L=P3
RR
RR
VRF
VRF
EBGP
L=Vx VPRN Label
VPNv4 UPD L=V1
VPNv4 UPD
L=V1
VPNv4 UPD
L=V1
L=Px BGP Next Hop
AS65534
AS65535
L=P1
ASBR
IP/MPLS
Backbone
OSSG257
RFC3107 for /32
PE Addresses
L=P2
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