Subject: AD Draft for HPR/ATM Architecture

From: "J. G. Dudley (444/4358)" <[email-masked]>
Date: Wed, 11 Oct 95 09:16:47 EDT

Yesterday, I put the AD draft for HPR/ATM in the HPR directory of the
AIW FTP site.  The file is atm-02.psbin.  Our schedule proposes AD
approval for this archiecture at AIW9 (starting 10/31/95).  Please
review this draft as soon as you can.  The changes in this version
are marked with change bars and include the following:

1. Ray Bird (IBM), who was the principal designer of the LDLC protocol,
   discovered a bug in the protocol.  The problem arises when an
   XID_DONE_RSP is lost.  In this case, if the node that sent the
   XID_DONE_RQ receives an NLP with data, that node should accept
   the data and use it as an indication that the XID_DONE exchange
   has completed.  To allow this result requires that LDLC be aware
   of incoming data.  To provide this awareness in the architectural
   model, the node structure (see Fig. 2-1) was changed such that
   incoming data is passed through LDLC.  This change rippled through
   several sections of the document.  See sections 2.1, 2.1.1, 2.4.1,
   and 2.4.2.2.
2. The nodal decomposition shown in section 2.1 was clarified by
   explaining how many logical instances of each component are
   required.
3. In the previous draft, section 2.7.1.1 included sequences for
   regular TG activation.  Sequences for regular TG deactivation
   were added.
4. In the previous draft, dedicated SVCs were established when an
   application specified its bandwidth requirements and TRS
   selected a route that included a "demand" connection network.
   A significant problem with this approach is how would TRS know
   to select a route through a demand connection network only in
   those cases when an application required guaranteed bandwidth.
   This design was changed such that a dedicated SVC is established
   when both the application requests dedicated SVC service and
   TRS selects a route that crosses a connection network between
   two nodes that support dedicated SVC service.  See section 2.7.3.
5. A regular TG requires definition of throughput parameters for
   both the forward and backward directions.  How the effective
   capacity TG characteristic should be set for regular TGs is
   clarified in section 2.8.2.
6. At AIW8, Jim Cobban (BNR) suggested that the default security TG
   characteristic should be changed to X'20' for WAN PVCs.  Section
   2.8.2 has been changed accordingly.
7. David Bryant (3Com) and Hoon Shin (IBM) suggested that connection
   network TGs should be marked as quiesced rather than nonoperational
   when either the port's link activation limit is reached or the
   port's upper bandwidth threshold is exceeded.  Sections 2.9 and
   2.10 have been changed accordingly.
8. The warning about defining regular TGs as auto-activatable when
   they support CP-CP sessions is clarified in section 2.12.
9. ATM signaling using the Broadband Low Layer Information (BLLI)
   IE is clarified for both multiprotocol shared SVCs and nonshared SVCs.
   In addition, a technique using multiple BLLI IEs for negotiating
   whether an SVC is shared and indicating the first using protocol
   is described.  See section 2.14.

Please post comments on this mail exploder.  I look forward to seeing
you at AIW9.

Regards,
Gary Dudley
IBM APPN Architecture Team