Technical Overview of L2TPv3

This section contains a brief overview of the L2TPv3. As noted in the introduction, there are three different L2TPv3 tunneling models: LAC to LNS, LNS to LNS, and LAC to LAC. This chapter discusses L2TPv3 deployed using the LAC to LAC pseudowire configuration.

L2TP can operate directly over several packet switched network types, including IP, MPLS, Frame Relay, and ATM. This chapter focuses on operation over an IP backbone network.

Internet Draft draft-ietf-l2tpext-l2tp-base discusses two methods of transporting L2TPv3 over an IP network:

  • L2TPv3 directly over IP (using IP Protocol ID 115)

  • L2TPv3 over UDP (using destination port 1701)

Cisco's current LAC to LAC implementation supports L2TPv3 over IP, so this method ...

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