Related Documentation
- ACX, M, MX, PTX, T Series
- Accepting Route Updates with Unique Inner VPN Labels in Layer 3 VPNs
Chained Composite Next Hops for Transit Devices
The Juniper Networks PTX Series Packet Transport Switch is principally designed to handle large volumes of transit traffic in the core of large networks. Chained composite next hops help to facilitate this capability by allowing a packet transport switch to process much larger volumes of routes. A chained composite next hop allows the packet transport switch to direct sets of routes sharing the same destination to a common forwarding next hop, rather than having each route also include the destination. In the event that a network destination is changed, rather than having to update all of the routes sharing that destination with the new information, just the shared forwarding next hop is updated with the new information. The chained composite next hops continue to point to this forwarding next hop which now contains the new destination.
When the next hops for MPLS LSPs are created on packet transport switches, the tag information corresponding to the inner-most MPLS label is extracted into a chained composite next hop. The chained composite next hop is stored in the ingress PFE. The chained composite next hop points to a next hop called the forwarding next hop that resides on the egress PFE. The forwarding next hop contains all of the other information (all of the labels except for the inner-most labels; and the IFA/IP information corresponding to the actual next hop node). Many chained composite next hops can share the same forwarding next hop. Additionally, separating the label from the forwarding next hop and storing it on the ingress PFE (within the chained composite next hop) helps to conserve egress PFE memory by reducing the number of rewrite strings stored on the egress PFE.
On PTX Series Packet Transport Switches, chained composite next hops are enabled by default for the following MPLS and VPN protocols and applications:
- Labeled BGP
- Layer 2 VPNs
- Layer 3 VPNs
- LDP
- MPLS
- Point-to-Multipoint LSPs
- RSVP
- Static LSPs
Related Documentation
- ACX, M, MX, PTX, T Series
- Accepting Route Updates with Unique Inner VPN Labels in Layer 3 VPNs
Published: 2013-02-28
Related Documentation
- ACX, M, MX, PTX, T Series
- Accepting Route Updates with Unique Inner VPN Labels in Layer 3 VPNs
