Alcatel-Lucent 7750 SR - RIP Metric Propagation in Vprns; Figure 138: RIP Metric Propagation in Vprns

Virtual Private Routed Network Services
7750 SR OS Services Guide Page 1097
RIP Metric Propagation in VPRNs
When RIP is used as the PE-CE protocol for VPRNs (IP-VPNs), the RIP metric is only used by
the local node running RIP with the Customer Equipment (CE). The metric is not used to or
encoded into and MP-BGP path attributes exchanged between PE routers.
The RIP metric can also be used to exchanged between PE routers so if a customer network is dual
homed to separate PEs the RIP metric learned from the CE router can be used to choose the best
route to the destination subnet. By using the learned RIP metric to se the BGP MED attribute,
remote PEs can choose the lowest MED and in turn the PE with the lowest advertised RIP metric
as the preferred egress point for the VPRN.
Figure 138: RIP Metric Propagation in VPRNs
OSSG181
VPRN A
7750-1
128.1.1.0/24
RIP: 128.1.1.0/24
Metric 2
7750-2
VPRN A
RIP: 128.1.1.0/24
Metric: 2 + Interface
Cost
MP-BGP: 128.1.1.0/24
MED 2