Supported Platforms
Load Balancing and IP Header Filtering for Layer 3 VPNs
You can now simultaneously enable both load balancing of traffic across both internal and external BGP paths and filtering of traffic based on the IP header. This enables you to configure filters and policers at the egress PE router for traffic that is simultaneously being load-balanced across both internal and external BGP paths. This feature is available only on the M120 router, M320 router, MX Series routers, and T Series routers.
To enable these features on a Layer 3 VPN routing instance, include the vpn-unequal-cost equal-external-internal statement at the [edit routing-instances routing-instance-name routing-options multipath] hierarchy level and the vrf-table-label statement at the [edit routing-instances routing-instance-name] hierarchy level.
If you issue the show route detail command, you can discover whether or not a route is being load-balanced (equal-external-internal) and what its interface index is.
If you have also configured fast reroute, please be aware of the following behavior:
- If an IBGP path goes down, it could be replaced by either an active EBGP path or an active IBGP path.
- If an EBGP path goes down, it can only be replaced by another active EBGP path. This prevents the forwarding of core-facing interface traffic to an IBGP destination.
 | Note: You can include the vpn-unequal-cost equal-external-internal statement and the l3vpn statement at the [edit routing-options forwarding-options chained-composite-next-hop ingress] hierarchy level simultaneously. However, if you do this, EBGP does not work. This means that when there are both paths with chained nexthops and paths with nonchained nexthops as candidates for EBGP equal-cost multipath (ECMP), the paths using chained nexthops are excluded. In a typical case, the excluded paths are the internal paths. |
