Information Technology Reference
In-Depth Information
When designing an RR-based MPLS VPN architecture, consider the following guidelines:
•
Partition RRs.
•
Move RRs out of the forwarding path.
•
Use a high-end processor with maximum memory.
•
Use peer groups.
•
Tune RR routers for improved performance.
Some of these points have been discussed elsewhere. The following sections discuss RR
partitioning and briefly RR router performance tuning.
Partitioning RRs
You can use a partition in an MPLS VPN environment to reduce the memory use on RRs.
The partition can take several forms:
•
Logical partition between RRs
•
Selective filtering between a PE and an RR
•
Selective filtering between RRs
•
Separation of IPv4 and VPNv4 RRs
Logical partition refers to different RRs for different VPNs or PE devices. Dedicated RRs
peer only with PEs that they serve. This method is simple to accomplish but requires more
hardware and more management.
Selective filtering can be implemented between a PE and an RR in that an RR accepts only
routes with a specific RT or RTs. This can be accomplished by using RR groups on the RR.
By default, RRs accept all the VPNv4 routes advertised by all the PEs they peer with. With
RR groups, an RR accepts only routes that are permitted by the configured RTs.
The RR group is configured under the VPNv4 address family with the command
bgp
rr-group
acl#
, where
acl#
is an ACL that specifies an extended community list. An
extended community list is like a numbered community list and has standard (1 to 99)
and expanded (100 to 199) formats. In the standard lists, only extended communities are
accepted; in the expanded lists, regular expressions are allowed.
Changes to the RR group cause route refresh requests to be sent out.
NOTE
