cleaned up question sheet

[Jim Boyle <jimpb@nc.rr.com>]

took a pass at cleaning up the question sheet, no new content.

------* snip here *--------
A. Definitions

1. In determining the specific requirements, the design team should
   precisely define  the concepts "survivability", "restoration",
   "protection", "protection switching", "recovery", "re-routing"
   etc. and their relations. This would enable the requirements doc to
   describe precisely which of these will be addressed. 

   In the following, the term "restoration" is used to indicate the broad
   set of policies and mechanisms used to ensure survivability.


B. Network types and protection modes

1. What is the scope of the requirements with regard to the types
    of networks covered? Specifically, are the following in scope:

    -  Restoration of connections in mesh optical networks
       (opaque or transparent)
    -  Restoration of connections in hybrid mesh-ring networks
    -  Restoration of LSPs in MPLS networks (composed of LSRs overlaid on a
       transport network, e.g., optical)
    -  Any other types of networks?
    -  Is commonality of approach, or optimization of approach more important?

2.  What are the requirements with regard to
     the protection modes to be supported in each network type covered?
     (Examples of protection modes include 1+1, M:N, shared mesh,
     UPSR, BLSR, newly defined modes such as P-cycles, etc.)

3.  What are the requirements on local span (i.e., link by link)
     protection and end-to-end protection, and the interaction between them?
     E.g.: what should be the granularity of connections for
     each type (single connection, bundle of connections, etc).

C. Hierarchy

1. Vertical (between two network layers):
    What are the requirements for the interaction between restoration
    procedures across two network layers, when these features are
    offered in both layers? 
    (Example, MPLS network realized over pt-to-pt
    optical connections.) Under such a case,

    (a) Are there any criteria to choose which layer should provide
          protection?

    (b) If both layers provide survivability features, what are the
          requirements to coordinate these mechanisms?

    (c) How is lack of current functionality of cross-layer
	  cooridnation currently hampering operations?

    (d) Would the benefits be worth additional complexity associated
          with routing isolation (e.g. VPN, areas), security, address
          isolation and policy / authentication processes?



2. Horizontal (between two areas or administrative subdivisions within
    the same network layer):

    (a) What are the criteria that trigger the creation of protocol or
          administrative boundaries pertaining to restoration? (e.g.,
          scalability?  multi-vendor interoperability? what are the
          practical issues?)  multi-provider? Should multi-vendor
          necessitate hierarchical seperation?

    When such boundaries are defined:

    (b) What are the requirements on how protection/restoration is
          performed end-to-end across such boundaries?

    (c) If different restoration mechanisms are implemented on two
          sides of a boundary, what are the requirements on their
          interaction?

   What is the primary driver of horizontal hierarchy? (select one)
    - functionality (e.g. metro -v- backbone)
    - routing scalability
    - signalling scalability
    - current network architecture, trying to layer on TE ontop of 
      already hiearchical network architecture
    - routing and signalling

   For signalling scalability, is it
    - managability
    - processing/state of network
    - edge-to-edge N^2 type issue

    For routing scalability, is it
    - processing/state of network
    - are you flat and want to go hierarchical
    - or already hierarchical?
    - data or TDM application?

D. Policy

1. What are the requirements for policy support during
protection/restoration,
    e.g., restoration priority, preemption, etc.

E. Signaling Mechanisms

1. What are the requirements on the signaling transport mechanism
   (e.g., in-band over sonet/sdh overhead bytes, out-of-band over
   an IP network, etc.) used to communicate restoration protocol
   messages between network elements. What are the bandwidth and
   other requirements on the signaling channels?

2. What are the requirements on fault detection/localization mechanisms
   (which is the prelude to performing restoration procedures)
   in the case of opaque and transparent optical networks?
   What are the requirements in the case of MPLS restoration?

3. What are the requirements on signaling protocols to be used in
   restoration procedures (e.g., high priority processing, security, etc).

4. Are there any requirements on the operation of restoration protocols?

E. Quantitative

1. What are the quantitative requirements (e.g., latency) for completing
   restoration under different protection modes (for both local and
   end-to-end protection)?

F. Management

1. What information should be measured/maintained by the control plane at
    each network element pertaining to restoration events?

2. What are the requirements for the correlation between control plane
    and data plane failures from the restoration point of view?