RFC 3386 (rfc3386) - Page 3 of 27
Network Hierarchy and Multilayer Survivability
Alternative Format: Original Text Document
RFC 3386 Hierarchy & Multilayer Survivability November 2002
proximity to the network fault. They operate primarily at a single
network layer. For hierarchy, there did not appear to be a driving
near-term need for work on "vertical hierarchy," defined as
communication between network layers such as Time Division
Multiplexed (TDM)/optical and Multi-Protocol Label Switching (MPLS).
In particular, instead of direct exchange of signaling and routing
between vertical layers, some looser form of coordination and
communication, such as the specification of hold-off timers, is a
nearer term need. For "horizontal hierarchy" in data networks, there
are several pressing needs. The requirement is to be able to set up
many Label Switched Paths (LSPs) in a service provider network with
hierarchical Interior Gateway Protocol (IGP). This is necessary to
support layer 2 and layer 3 Virtual Private Network (VPN) services
that require edge-to-edge signaling across a core network.
This document presents a proposal of the near-term and practical
requirements for network survivability and hierarchy in current
service provider environments. With feedback from the working group
solicited, the objective is to help focus the work that is being
addressed in the TEWG (Traffic Engineering Working Group), CCAMP
(Common Control and Measurement Plane Working Group), and other
working groups. A main goal of this work is to provide some
expedience for required functionality in multi-vendor service
provider networks. The initial focus is primarily on intra-domain
operations. However, to maintain consistency in the provision of
end-to-end service in a multi-provider environment, rules governing
the operations of survivability mechanisms at domain boundaries must
also be specified. While such issues are raised and discussed, where
appropriate, they will not be treated in depth in the initial release
of this document.
The document first develops a set of definitions to be used later in
this document and potentially in other documents as well. It then
addresses the requirements and issues associated with service
restoration, hierarchy, and finally a short discussion of
survivability in hierarchical context.
Here is a summary of the findings:
A. Survivability Requirements
o need to define a small set of interoperable survivability
approaches in packet and non-packet networks
o suggested survivability mechanisms include
- 1:1 path protection with pre-established backup capacity (non-
shared)
- 1:1 path protection with pre-planned backup capacity (shared)
Lai, et. al. Informational