Operation Of Mpls Ip Vpn - Avaya 8800 Planning And Engineering, Network Design

MPLS IP VPN and IP VPN Lite
labels, initiated at the ingress node. Packets that require the same treatment for transport through
the network are grouped into a forwarding equivalence class (FEC).
The following figure shows a sample MPLS network.
Figure 115: Label Switched Path and Forwarding Equivalent Class
The FECs are identified by the destination subnet of the packets to be forwarded. All packets in the
same FEC use the same LSP to travel across the network. Packets are classified once, as they
enter the network; all subsequent forwarding decisions are based on the FEC to which each packet
belongs (that is, each label corresponds to a FEC).

Operation of MPLS IP VPN

MPLS IP-VPN enabled routers use two labels as shown in the following figure. The Avaya Ethernet
Routing Switch 8800/8600 uses LDP for IP VPN. LDP generates and distributes an outer label
referred as a tunnel label, which is in fact the LSP. BGP-MP generates and distributes the inner
label referred to as the VPN label.
Figure 116: IP VPN packet forwarding
June 2016 Planning and Engineering — Network Design
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