Subject: Minutes of HPR SIG meeting at AIW 8

From: "Marcia Peters (8-444-4380)" <[email-masked]>
Date: Mon, 28 Aug 95 16:34:10 EDT

____________________________________________________________________

                 8th APPN Implementers' Workshop
                       Raleigh, NC, USA
                        August 23, 1995

                       HPR SIG - MINUTES
____________________________________________________________________

OLD BUSINESS

Ray Bird reviewed fixes to HPR4, the current HPR architecture document.
An updated version should be available in a few weeks.

- Products need to save the COS/TPF CV in case they become an RTP
  endpoint as the result of Route Setup backout.  It is recommended to
  save the whole message, in case there is a future need to refer to
  other Route Setup CVs.  DCL suggested that the fix be put in Border
  Node.  Ray said that would be more complex and might not work.  We
  concluded that this fix should not be put in BN.  However, the
  discussion revealed a problem with existing COS mapping across BNs
  that needs to be looked at.  The resolution of that issue could affect
  RTP endpoints.

- A new sense code for Route Setup timer expiration was discussed.
  Should we have a Route Setup Timer?  Optional.  Should we have a
  default timer value (5, 10, or 15 minutes)? 10 minutes preferred.
  Should we allow Route Setup timer in intermediate nodes?  Optional.

- Can a node discard Locates or Route Setups if it gets overrun?  We
  concluded that it is wrong to do this.

- A proposal was made concerning SDLC support.  We agreed it was OK to
  make ERP (what NCP shipped) base function for SDLC.  Sending UI on
  SDLC is complicated (e.g. multipoint).  The SIG can address this in
  the future if any requirements arise.

- Ray went over editorial changes to HPR4:
     - "Topology Awareness of CP-CP Sessions" is required for CP-CP
       sessions on RTP connections.
     - Limited resource link deactivation was clarified:  it requires
       no APPN (ISR) sessions and no RTP connections on the link.
     - HPR option set numbers were defined.
     - CVs on negative Route Setup reply were clarified
     - Path switch timer default values were suggested.

NEW BUSINESS

We reviewed a proposal by Jim Cobban (Nortel) for an LLC2-free option
set.  This is motivated by the limitation of 255 LLC2 connections per
gateway.  The LLC2 RR traffic is wasteful (one RR every 30 sec. x
thousands of link stations).  Please review the mail exploder for full
details on this.

- One big issue is the need to detect link failure or adjacent link
  station failure.  One way to do this requires the Control Flows Over
  RTP tower, where the CP-CP RTP connection performs the keepalive
  function.  However, this fails to detect link failure within an
  multilink transmission group (MLTG), since packets are not guaranteed
  to flow over any particular link.  We determined that HPR MLTGs are
  workable, at least between NCPs.  It was then proposed to require LLC2
  over an MLTG.  We need to get NCP's input on this.

- Reinventing a keepalive mechanism could reintroduce as much overhead
  as the proposal is trying to eliminate.

- Ray made a few additional points:
       - XID exchanges have to end with PRI/SEC roles negotiated.
       - Need some type of exchange to signify XID negotiation is done
         (currently SABME/UA).
          - The primary must be able to receive the "Done" RSP or data
            (in case "Done" RSP is lost).

The chair requested input on whether the HPR SIG should disband or
extend its charter to new work.  IBM proposed that the HPR SIG charter
be expanded to develop a native ATM access architecture for APPN.  AIW
members had already agreed to make HPR a prerequisite for APPN over ATM,
and IBM was submitting a HPR/ATM draft containing a proposal that
eliminates the use of LLC2 in this environment.  The SIG agreed on
expanding its charter, pending approval of the ATM BOF the following
day.

The ATM BOF agreed, and the decision was ratified by the AIW plenary.
I intend to submit a proposed amended charter for SIG members' approval
shortly.

Marcia Peters, Chair

_________________________________________________________________________
 Marcia L. Peters                           Marcia_Peters @ vnet.ibm.com
 Advanced Peer-to-Peer Networking
 IBM Corp., Dept. BUFA, Bldg. 664
 P.O. Box 12195                             Phone:         (919) 254-4380
 Research Triangle Park, NC 27709           Fax:           (919) 254-5483