Network Working Group D. Awduche
Request for Comments: 3210 Movaz Networks
Category: Informational A. Hannan
Applicability Statement for Extensions to RSVP for LSP-Tunnels
Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright (C) The Internet Society (2001). All Rights Reserved.
This memo discusses the applicability of "Extensions to RSVP
(Resource ReSerVation Protocol) for LSP Tunnels". It highlights the
protocol's principles of operation and describes the network context
for which it was designed. Guidelines for deployment are offered and
known protocol limitations are indicated. This document is intended
to accompany the submission of "Extensions to RSVP for LSP Tunnels"
onto the Internet standards track.
Service providers and users have indicated that there is a great need
for traffic engineering capabilities in IP networks. These traffic
engineering capabilities can be based on Multiprotocol Label
Switching (MPLS) and can be implemented on label switching routers
(LSRs) from different vendors that interoperate using a common
signaling and label distribution protocol. A description of the
requirements for traffic engineering in MPLS based IP networks can be
found in . There is, therefore, a requirement for an open, non-
proprietary, standards based signaling and label distribution
protocol for the MPLS traffic engineering application that will allow
label switching routers from different vendors to interoperate.
The "Extensions to RSVP for LSP tunnels" (RSVP-TE) specification 
was developed by the IETF MPLS working group to address this
requirement. RSVP-TE is a composition of several related proposals
Awduche, et. al. Informational [Page 1]RFC 3210 Applicability Statement for Extensions December 2001
submitted to the IETF MPLS working group. It contains all the
necessary objects, packet formats, and procedures required to
establish and maintain explicit label switched paths (LSPs).
Explicit LSPs are foundational to the traffic engineering application
in MPLS based IP networks. Besides the traffic engineering
application, the RSVP-TE specification may have other uses within the
This memo describes the applicability of the RSVP-TE specifications
. The protocol's principles of operation are highlighted, the
network context for which it was developed is described, guidelines
for deployment are offered, and known protocol limitations are
This applicability statement concerns only the use of RSVP to set up
unicast LSP-tunnels. It is noted that not all of the features
described in RFC2205  are required to support the instantiation
and maintenance of LSP-tunnels. Aspects related to the support of
other features and capabilities of RSVP by an implementation that
also supports LSP-tunnels are beyond the scope of this document.
However, support of such additional features and capabilities should
not introduce new security vulnerabilities in environments that only
use RSVP to set up LSP-tunnels.
This applicability statement does not preclude the use of other
signaling and label distribution protocols for the traffic
engineering application in MPLS based networks. Service providers
are free to deploy whatever signaling protocol that meets their
In particular, CR-LDP  and RSVP-TE  are two signaling protocols
that perform similar functions in MPLS networks. There is currently
no consensus on which protocol is technically superior. Therefore,
network administrators should make a choice between the two based
upon their needs and particular situation.
2.0 Technical Overview of Extensions to RSVP for LSP Tunnels
The RSVP-TE specification extends the original RSVP protocol by
giving it new capabilities that support the following functions in an
(1) downstream-on-demand label distribution
(2) instantiation of explicit label switched paths
(3) allocation of network resources (e.g., bandwidth) to