Subject: I-D ACTION:draft-ietf-tewg-restore-hierarchy-01.txt

From: [email-masked]
Date: Wed, 24 Jul 2002 08:09:23 -0400

A New Internet-Draft is available from the on-line Internet-Drafts directories.
This draft is a work item of the Internet Traffic Engineering Working Group of the IETF.

	Title		: Network Hierarchy and Multilayer Survivability
	Author(s)	: W. Lai et al.
	Filename	: draft-ietf-tewg-restore-hierarchy-01.txt
	Pages		: 25
	Date		: 23-Jul-02
	
This document is the deliverable out of the Network Hierarchy 
and Survivability Techniques Design Team established within the 
Traffic Engineering Working Group.  This team collected and 
documented current and near term requirements for survivability 
and hierarchy in service provider environments.  For clarity, 
an expanded set of definitions is included.  The team 
determined that there appears to be a need to define a small 
set of interoperable survivability approaches in packet and 
non-packet networks.  Suggested approaches include path-based 
as well as one that repairs connections in 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 TDM/optical and 
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 LSPs in a service 
provider network with hierarchical IGP.  This is necessary to 
support layer 2 and layer 3 VPN services that require edge-to-
edge signaling across a core network.  
Please send comments to [email-masked]

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