Link-Layer Support

MPLS supports the following link-layer protocols, which are all supported in the JUNOS MPLS implementation:

• Point-to-Point Protocol (PPP)—Protocol ID 0x0281, Network Control Protocol (NCP) protocol ID 0x8281.
• Ethernet/Cisco High-level Data Link Control (HDLC)—Ethernet type 0x8847.
• Asynchronous Transfer Mode (ATM)—Subnetwork attachment point encoded (SNAP-encoded) Ethernet type 0x8847. Support is included for both point-to-point mode or nonbroadcast multiaccess (NBMA) mode. Support is not included for encoding MPLS labels as part of ATM virtual path identifier/virtual circuit identifier (VPI/VCI).
• Frame Relay—SNAP-encoded, Ethernet type 0x8847. Support is not included for encoding MPLS labels as part of Frame Relay data-link connection identifier (DLCI).
• Generic routing encapsulation (GRE) tunnel—Ethernet type 0x8847.