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 ...