JUNOS High Availability

MPLS Signaling for High Availability

As previously mentioned, MPLS is unable to function at scale without the assistance of a signaling protocol. Signaling protocols come in many flavors, including standards-based and vendor-proprietary. Table 16-1 compares Juniper and Cisco support for various MPLS signaling protocols.

Table 16-1. Juniper and Cisco support for MPLS signaling protocols

Signaling protocol	Juniper support	Cisco support	Notes
Tag Distribution Protocol (TDP)	No	Yes	TDP is a Cisco-proprietary protocol.
Label Distribution Protocol (LDP)	Yes	Yes	Both Cisco and Juniper support LDP.
Resource Reservation Protocol (RSVP)	Yes	Yes	Supported by both Juniper and Cisco.
Resource Reservation Protocol with Traffic Engineering (RSVP-TE)	Yes	Yes	Functionality is supported by both Juniper and Cisco. The Juniper protocol naming convention does not draw a distinction between RSVP and RSVP-TE.
Static	Yes	No	Supported on Juniper platforms, though seldom used in high availability environments.
Constraint-Based Routing Label Distribution Protocol (CR-LDP)	No	No	This signaling protocol is supported by neither Juniper nor Cisco. It was deprecated by the Internet Engineering Task Force (IETF) in 2003.

With these considerations in mind, the only realistic choice of MPLS signaling protocols for label-switched paths (LSPs) that can cross between Juniper and Cisco routers is LDP for nontraffic-engineered applications, and RSVP for situations where traffic engineering is desirable. These are the only two signaling methods supported ...