Subject: [PWE3] pwID and pwe3-pw-mib-10 reverse mapping tables

From: "Ben Wright" <[email-masked]>
Date: Tue, 27 Feb 2007 13:23:49 -0000

All, 

I'd like to propose a minor modification to the pwID field in the pwTable.  

For the reverse mappings provided by pwIndexMappingTable and pwPeerMappingTable, a unique pwID is required.  However, the description of pwID does not require uniqueness, and fixes pwID to zero for static PWs (where no pwID is signaled).  In practice this is restrictive for 'manual' PWs, where these reverse mappings (particularly that provided by the pwPeerMappingTable) are still useful.

For the pwID change, I'd suggested the following text.  Does anyone have any comments on this new definition?   

Change from:
DESCRIPTION
  "Used in the outgoing PW ID field within the 'Virtual
  Circuit FEC Element'.
  Applicable if pwOwner equal 'pwIdFecSignaling' or
  'l2tpControlProtocol', otherwise it SHOULD be set to zero."
 
Change to:
  "Pseudo Wire identifier.
 
  If the pwOwner object is 'pwIdFecSignaling' or
  'l2tpControlProtocol', then this object is signaled in the
  outgoing PW ID field within the 'Virtual Circuit FEC
  Element'. For other values of pwOwner, this object is not
  signaled and it MAY be set to zero.
 
  For implementations that support the pwIndexMappingTable, 
  a non-zero value is RECOMMENDED, even if this
  identifier is not signaled.  This is so that reverse
  mappings can be provided by pwIndexMappingTable and
  pwPeerMappingTable.  It is therefore RECOMMENDED that the
  value of this pwID be unique (or if pwPeerAddrType is not
  'unknown', at least <pwType,pwID,pwPeerAddrType,pwPeerAddr>
  is unique.)" 

Note that a similar issue exists for PWs that correspond to FEC 129, but the reverse mapping tables (as they stand) do not handle these FECs.   

Ben Wright

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