Subject: Minutes of Architecture Reference SIG meeting at AIW7

From: "Ralph Case" <[email-masked]>
Date: Thu, 29 Jun 95 08:40:29 EDT

MINUTES OF ARCHITECTURE REFERENCE SIG AT AIW7
_____________________________________________

  This SIG discusses clarifications, fixes, and minor
  enhancements to the APPN architecture.  The focus is on
  improving the quality and interoperability of APPN
  Implementations.

  If we've missed something from the meeting, or if you
  have additional questions or comments, please post them
  here or send them directly to me.

  I'd like to thank everyone who participated in the
  discussions at the SIG meeting.  I think we had a
  valuable exchange of ideas.  I look forward to continuing
  these discussions and seeing them result in improvements
  to APPN architecture and product implementations.  I'd
  especially like to thank those who took the time and
  effort to prepare presentations:

  o   Andy Barclay
  o   Jim Cobban
  o   Jim Fletcher
  o   Tim Hefel
  o   Marcia Peters
  o   Gary Schultz
  o   Ed Tremblay

ARCHITECTURE UPDATES AND DISCUSSIONS
____________________________________

  This is a brief record of the discussions.  See the various
  mail logs for additional discussion on many of the topics.

BASE / OPTIONS UPDATE

  This was discussed at AIW6.  There is a consensus that
  there is no need to pursue this work any further at this
  time.

ENHANCED TOPOLOGY GARBAGE COLLECTION AND UNKNOWN CVS IN A TDU

  This item is documented in arch8084f.psbin,
  arch8102.psbin, and arch8200f.psbin.  There was consensus
  the proposal be included in the next version of APPN as a
  base function.  This item is now approved.

TDU WAR DETECTION AND ELIMINATION

  This item is documented in arch6308.psbin.  There was
  consensus the proposal be included in the next version of
  APPN as a base function.  This item is now approved.

DETECTING NNS WITH DUPLICATE CP NAMES WHEN ONE IS A VRN

  Tim Hefel (IBM) proposed a solution to this problem,
  which is documented in arch8265.  There was some
  discussion that both sense codes and alerts are needed to
  flag this condition.  There was also a concern that the
  proposed solution may be worse than the condition in some
  cases.  It was agreed that this item needs more work.  A
  new proposal will be posted.

MODIFICATIONS TO SESSION ROUTE BUILDING

  (Improvement to Topology Nonverify Algorithm)

  Tim Hefel (IBM) presented changes to a proposal that was
  initially made at AIW6.  The current proposal is
  documented in arch8264 and arch8083.  A couple of
  additional changes were requested.  Tim will modify his
  proposal based on the discussion and request approval
  electronically.

ALLOWING NNS TO IGNORE COS SUPPLIED BY CLIENT END NODES

  Tim Hefel (IBM) presented a proposal to help solve a
  network management concern.  This proposal is described
  in arch8266.  There was interest in addressing the base
  concern - preventing end users from selecting priorities
  that network administrators do not want.  However, there
  was also a discussion that restricting mode-to-COS
  mapping may not solve the problem since users may be able
  to choose different modes.  Also, this function is an
  example of EN authorization concerns, but there may be
  others.  It was decided to continue these discussions on
  the mail exploder.

GENERALIZED ODAI USE

  Gary Schultz (IBM) described the resolution of this issue
  that was originally discussed at AIW5.  Pages have been
  posted as several files with '8128' in the file name;
  odairoot.psbin describes the affected documents.  We are
  now seeking approval on these changes.

NON-CANONICAL ENCODINGS FOR TOKEN RING SIGNALLING INFORMATION IN DLUR

  This item is documented in abs8229.txt and
  arch8229d.psbin.  This was discussed at AIW6.  Comments
  were  requested by 3/14/95.  None were received, so this
  is now APPROVED.

ADD XID1 SUPPORT TO DLUR/S

  This item is documented in abs8256.txt and
  arch8256d.psbin.  At the meeting, these additions were
  approved as part of the DLUR base.

CORRECT SENSE DATA ENCODING IN DLUR PROTOCOL ERROR ALERT

  This item is documented in abs8257.txt and
  arch8257d.psbin.  At the meeting, these additions were
  approved as part of the DLUR base.

CORRECT ACTIONS ENCODING AND ORDERING IN DLUR CONFIGURATION ERROR ALERTS

  This item is documented in abs8258.txt and
  arch8258d.psbin.  At the meeting, these additions were
  approved as part of the DLUR base.

FURTHER CLARIFY DLUR PROCESSING OF SHORT RSP(BIND) RUS

  This item is documented in abs8259.txt and
  arch8259d.psbin.  At the meeting, these additions were
  approved as part of the DLUR base.

ADD DLUR PROCESSING OF WHOLE BIUS REQUIRED INDICATOR (WBRI)

  This item is documented in abs8259.txt and
  arch8259d.psbin.  At the meeting, these additions were
  approved as part of the DLUR base.

ADD DLUR PROCESSING OF EXTENDED UNBIND RUS

  This item is documented in abs8259.txt and
  arch8259d.psbin.  At the meeting, these additions were
  approved as part of the DLUR base.

DLUR SIGNALLING INFORMATION DEFINITION

  This was a new discussion regarding where signalling
  information can be defined for DLUR.  It was agreed that
  more discussion and work is needed.  A summary of some of
  the discussion follows.

  DLUR signalling information is currently defined DLCADDR
  at the DLUS.  While some users prefer centralized (at
  DLUS) definition, others may prefer distributed (at DLUR)
  definition.  Some or all of the information currently
  defined via DLCADDR should be allowed to be optionally
  defined at the DLUR instead.  This would allow much more
  flexibility on how information is defined and managed.

  There was some discussion on how to resolve cases of
  conflicting definition at the DLUR and DLUS.  It was
  proposed that whichever side initiates the session can
  override remote definitions with its own.

  There was some concern that this discussion is
  constrained by what the DLUS does, but VTAM may be
  willing to change to accommodate the AIW recommendations
  in this area.

PUBLIC DATA NETWORKS SIGLET

  Jim Cobban (Nortel) led a discussion of several items.

PPP code points for SNA

  This is documented in RFC 1700 (Oct. 1994)

      004B - SNA_OVER_802.2  (APPN, HPR ERP)

      004D - SNA             (HPR non-ERP)

      804B - SNA_OVER_802.2 CONTROL PROTOCOL

      004D - SNA CONTROL PROTOCOL

Switched Data Networks

  There were four major discussions, summarized here.

  1.  Media Address Signalling

      The connection network model should be applied to
      exploit switched networks.  Current connection
      network architecture applies to LAN only.  Signalling
      information is communicated between APPN nodes using
      CV 46, subfield 82.  DLUR defines additional
      subfields for additional DLC types.  These formats
      should be allowed on CV 46 for CNs as well as for
      DLUR.

      In the current architecture, configuration services
      (CS) is aware of media-dependent information.  These
      differences are also visible to NOF.  As we add new
      media types, we should consider defining the
      architecture protocol boundaries in a way that avoids
      media-dependencies.

  2.  Media with mixed metrics

      The CN model also assume that the characteristics of
      the media are the same for all nodes on the CN.  This
      is not really true for switched media.  However,
      while there are cases that break down, in general,
      delay and cost do not vary much.  Bridged LANs may
      also have variation, but that does not eliminate the
      usefulness of the CN model.

      There seemed to be a general agreement that this
      problem can be deferred for now.

  3.  COS -> QOS mapping

      It was pointed out that current COS tables are
      inadequate to provide the desired separation of
      traffic in certain cases in a switched environment.
      We should seriously consider changes to APPN
      architecture in this area.

      There are also several different ways to map TGs to
      VCs.  We need to get a clear description of
      requirements and some specific proposals on the table
      to discuss.

      This topic is being discussed further in the
      aiw-appn-atm mail group.

  4.  Sharing media with other protocols

      Most implementations will include not only APPN, but
      also other protocols.  We need to understand this as
      a requirement in any work to enhance APPN.

DLUR Signalling Formats

  Andy Barclay (IBM) has proposed a set of extensions to
  DLUR to allow signalling for additional down-stream link
  types.  There was some discussion of these formats.  Andy
  has revised the proposal based on this discussion, and
  posted the revisions.  Comments were due by 6/10/95, and
  none were received, so Andy's proposal is now approved.

ADJACENT CP NAME CHANGE (FUNCTION SET 1004)

  Marcia Peters (IBM) answered some questions and made some
  clarifications about non-activation XID exchanges that
  can (and can't) happen during an SSCP takeover.

PARALLEL TG LEN-APPN MIGRATION

  Marcia Peters (IBM) explained some details of the
  differences between LEN and APPN support in VTAM, and how
  this affects migration.

XID3 BYTE 27

  The architecture is ambiguous as to how this byte is
  used.  Different products do different things.  An
  architecture clarification is needed.  Proposed changes
  will be submitted to the AIW.

FORWARDING A BIND RECEIVED OVER A LEN CONNECTION

  Ralph Case (IBM) discussed a flaw in the architecture
  that prevents LEN connections from being used between
  network nodes in some cases.  A proposed fix was
  presented.  This fix will be documented and submitted for
  approval.

LOCATE TIMEOUTS

  Jim Fletcher (IBM) discussed the need for extending APPN
  architecture to define a process for handling "lost"
  Locates.  This would be useful to help isolate and
  recover from certain types of network failures.

SNMP OVER SNA

  Bob Moore (IBM) submitted a proposal for this function.
  The submission is documented in aiw/snasnmp/snmpsna.txt.
  A BOF met and decided to ask for approval at the
  Architecture Reference SIG.  The time for comments has
  expired, so this is now approved.

DISCOVERY

  While not strictly covered by the APPN architecture, this
  has been discussed at previous AIWs.  Discovery is viewed
  as a valuable function, and AIW members would like an
  update on what IBM's plans are for making it available.

NON-LU RESOURCES

  There was some interest in this topic as well.  The
  requirements are not clearly defined, but several
  proposed uses of APPN directory services were discussed
  that would require support for resource types other than
  "LU." An API to access these services would be required
  as well.  The CIW should follow up on how to make it
  available to application programmers.  Several people
  expressed interest in working on a proposal.

FUTURE WORK
___________

  It was suggested that this SIG develop a more organized
  way to focus its efforts on what enhancements need to be
  made to APPN.  There will always be some amount of
  maintenance type work that will be hard to predict, but
  if there are specific enhancements desired, we should
  agree on their priorities.

  Members should send a list of desired enhancements to
  this mail group.  I will collect them into a matrix like
  the one the DLSw group used to prioritize their work.

PROCEDURES
__________

  Some of the items we discuss are so small that following
  the AIW procedures for AD/AP/CP approval seems like
  overkill.  On the other hand, some of the items are large
  enough that they would benefit from some better
  description of their current status.  As new items are
  presented, the SIG should decide which track is
  appropriate - all approval steps or straight to CP.

  All references to the "architecture repository" in these
  minutes refer to the /pub/standards/aiw/appn/architecture
  directory on the networking.raleigh.ibm.com host.  Files
  are available via anonymous FTP.  Most files were also
  included in the binder for easy reference at the meeting.

  I will update the architem file to reflect these new
  status changes to the architecture items.

Ralph Case                    [email-masked]    (919)254-1882
APPN/APPC Architecture
IBM Networking Hardware Division