Configuring the Encapsulation on Interfaces Participating in the Layer 2.5 VPN

The encapsulation types used for Layer 2.5 VPNs are parallel to CCC encapsulations and identical to the TCC encapsulations explained in Configuring TCC Interface Switching. The encapsulation types are:

• atm-tcc-vc-mux
• atm-tcc-snap
• cisco-hdlc-tcc
• ethernet-tcc
• extended-vlan-tcc
• frame-relay-tcc
• ppp-tcc

When you configure a TCC encapsulation type, some modifications are needed to handle VPN connections over unlike Layer 2 links and to terminate the Layer 2 protocol locally. The router performs the following media-specific changes:

• PPP TCC—Both Link Control Protocol (LCP) and Network Control Protocol (NCP) are terminated on the router. Internet Protocol Control Protocol (IPCP) IP address negotiation is not supported. The JUNOS software strips all PPP encapsulation data from incoming frames before forwarding them. For frames destined to a PPP-connected neighbor, PPP encapsulation is added.
• Cisco HDLC TCC—Keepalive processing is terminated on the router. The JUNOS software strips all Cisco HDLC encapsulation data from incoming frames before forwarding them. Cisco-HDLC encapsulation is added onto frames that are destined to a Cisco HDLC-connected neighbor.
• Frame Relay TCC—All Local Management Interface (LMI) processing is terminated on the router. The JUNOS software strips all Frame Relay encapsulation data from incoming frames before forwarding them. For frames destined to a Frame Relay-connected neighbor, Frame Relay encapsulation is added.
• ATM—Operation, Administration, and Maintenance (OAM) and Interim Local Management Interface (ILMI) processing is terminated at the router. Cell relay is not supported. The JUNOS software strips all ATM encapsulation data from incoming frames before forwarding them. ATM encapsulation is added onto frames that are destined to an ATM-connected neighbor.

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