MPLS: building blocks
Label: short, fixed length field
Forwarding table structure:
- Incoming label + subentry = outgoing label, outgoing interface, next-hop address (will include PHBs for diff-serv)
Carrying label in header:
- Use VCI/VPI or DLCI in ATM or FR
- New “shim” header for other link layers
Forwarding algorithm: Label swapping.
- Use label as an index (exact match)
Control component:
- Responsible for distributing routing & label-binding information: extensions to routing protocols, RSVP, LDP