4
Figure 4
Dynamic LSP establishment
MPLS forwarding
Figure 5
MPLS forwarding
As shown in
, a packet is forwarded over the MPLS network in the following steps:
1.
Router B (the ingress LSR) receives a packet with no label. It then does the following:
a.
Identifies the FIB entry that matches the destination address of the packet.
b.
Adds the outgoing label (40, in this example) to the packet.
c.
Forwards the labeled packet out of the interface VLAN-interface 20 to the next hop LSR Router
C.
2.
When receiving the labeled packet, Router C processes the packet as follows:
a.
Identifies the LFIB entry that has an incoming label of 40.
b.
Uses the outgoing label 50 of the entry to replace label 40 in the packet.
