Routing Using Matching and Calculated LSP Next Hops
Normally, a route table prefix is associated with a gateway or next hop IP address.
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Matching LSP next hop
An LSP is considered matching with respect to an FEC if it has been associated with that FEC via LDP or RSVP-TE. An example of this is an IPv4 prefix for which a matching label mapping has been received by LDP. Matching LSPs are supported for all route origin types.
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Calculated LSP next hop
An LSP is considered calculated with respect to an FEC if it has been associated with that FEC through a routing protocol. Both OSPF and BGP can perform the calculations necessary to associate a route table prefix with an LSP next hop.
Matching and Calculated LSP Next Hops illustrates the concept of matching and calculated LSPs.
Label Bindings for LSR A describes the label bindings in the MPLS forwarding table for LSR A that are maintained for FECs reachable via LSR A to LSR C, shown in Matching and Calculated LSP Next Hops.
| Destination | Next Hop | Matching LSP Next Hop Label | Calculated LSP Next Hop Label |
|---|---|---|---|
| 10.1.1.1/32 | 10.2.1.1 | 31 | 30 |
| 10.0.1.0/24 | 10.2.1.1 | 32 | 31 |
| 10.0.2.0/24 | 10.2.1.1 | 33 | 31 |
| 10.0.3.0/24 | 10.2.1.1 | 34 | 31 |