draft-ietf-tewg-restore-hierarchy-00.txt => CCAMP Attention

[Jim Boyle <jboyle@pdnets.com>]

This message is to announce that the document:

        draft-ietf-tewg-restore-hierarchy-00.txt

which was originated out of a service provider focussed design team, and
then discussed within the TEWG and adopted as a WG item is ready for
consideration by CCAMP.  IPO members were also solicited for feedback on
this document via the TEWG mailing list.

The requirements for restoration and hieararchy that are expressly needed
at this time are summarized in the introduction of the document.

   A. Survivability Requirements

   @ need to define a small set of interoperable survivability
     approaches in packet and non-packet networks
   @ 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)
     -  local restoration with repairs in proximity to the network
         fault
     -  path restoration through source-based rerouting
   @ timing bounds for service restoration to support voice call cutoff
     (140 msec to 2 sec), protocol timer requirements in premium data
     services, and mission critical applications
   @ use of restoration priority for service differentiation

   B. Hierarchy Requirements

   B.1. Horizontally Oriented Hierarchy (Intra-Domain)

   @ ability to set up many LSPs in a service provider network with
     hierarchical IGP, for the support layer 2 and layer 3 VPN services
   @ requirements for multi-area traffic engineering need to be
     developed to provide guidance for any necessary protocol
     extensions

   B.2. Vertically Oriented Hierarchy

   The following functionality for survivability is common on most
   routing equipment today.

   @ near-term need is some loose form of coordination and
     communication based on the use of nested hold-off timers, instead
     of direct exchange of signaling and routing between vertical
     layers
   @ means for an upper layer to immediately begin recovery actions in
     the event that a lower layer is not configured to perform recovery

   C. Survivability Requirements in Horizontal Hierarchy

   @ protection of end-to-end connection is based on a concatenated set
     of connections, each protected within their area
   @ mechanisms for connection routing may include (1) a network
     element that participates on both sides of a boundary (e.g., OSPF
     ABR) - note that this is a common point of failure; (2) route
     server
   @ need for inter-area signaling of survivability information (1) to
     enable a "least common denominator" survivability mechanism at the
     boundary; (2) to convey the success or failure of the service
     restoration action;  e.g., if a part of a "connection" is down on
     one side of a boundary, there is no need for the other side to
     recover from failures

Regards,

Jim Boyle, Ed Kern, & TEWG