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                          ADDENDUM TO
                       TOPS-20 NETWORKS
                       PROJECT PLAN FOR
                DECNET-20 VERSIONS 1.0 AND 2.0
Addendum to TOPS-20 Networks Project Plan for DECnet-20  Page 2


The RSX-11M prototype Phase  III  routing  node  can  currently
communicate  point-to-point with Phase II products which do not
implement  intercept.   This   communication   employs   simple
compatibility  code  in  the  routing  node.   The DRG approved
version of the Transport Specification documents the technique.
This  technique permits the evolution of non-intercept Phase II
nodes to Phase III nodes by conversion one at a  time.   At  no
time  in  this  process  does  any communication capability get

Unfortunately,  no  such  technique  has   been   devised   for
communication  between  DECnet-20  and  Phase III routing nodes
where a DN20 intercept node is  used.   As  this  communication
capability is as much a goal of the DECnet Program as any other
Phase  II  to  Phase  III  capability,  it  is  essential  that
DECnet-20 communicate successfully to Phase III nodes.

After  reviewing  the  several  alternative  solutions  to  the
problem  of intercept nodes communicating with Phase III nodes,
the  selected  algorithm  is  one  termed  "False  Node  Init".
Briefly,  this  algorithm  causes  the DN20 DECnet front end to
appear to all nodes but the 2040/50/60 to which it  is  coupled
as  the  2040/50/60 node.  This means that it will no longer be
an intercept node to the network.  It will still appear  to  be
an  intercept  node  to  the  2040/50/60 and continue to behave
exactly the same as previously for the  host  system.   Further
detail of this algorithm is supplied later in this document.

This addendum to the final networks plan defines the  new  plan
required for DECnet-20 Task-to-Task to be compatible with Phase
III  routing  nodes  by  implementing  the  "False  Node  Init"
algorithm.  This plan is designed to have minimal impact to the
Release 4 Program.

Functionally, the user will see no change in the  product  from
the  DECnet-20  Version  1.0 product in the same configuration.
It is important to note, however, that this new algorithm  WILL
change  the  topological  considerations  from  those initially
anticipated for the Version 2.0 product.  We are fortunate that
a  multiple  line  product has not been released, as this would
have created several problems.

2.0  GOALS

The goals of this Project revision are:

     1.  Continued  compatibility  with  all  Phase  II  DECnet
Addendum to TOPS-20 Networks Project Plan for DECnet-20  Page 3

     2.  Phase II type compatibility with the DECnet  Transport

     3.  Extensive system test to minimize the risks associated
         with   implementing  critical  code  so  late  in  the

     4.  No, or at least minimal, impact on the TOPS-20 Release
         4 Program schedule.

The non-goals of this project revision are:

     1.  Guaranteed Phase III routing node compatibility.
         It is the Phase III products that must be (and  prove)
         compatibility  with  this  implementation, as with any
         other Phase II implementation.

     2.  Specifically  excluding  the  use  of  the   intercept
         functions  available  within  the  DN20  to any system
         attempting to use it.

     3.  Specifically  including  the  use  of  the   intercept
         functions  available  within  the  DN20  to any system
         attempting to use it.


3.1  Unit Test

The tests,  procedures,  and  timing  of  this  phase  are  the
responsibility   of  the  developers  and  must  fit  into  the
framework of the overall implementation plan.  This means  that
a  system  using  "False  Node  Init",  which  is  felt  by the
developers can successfully connect, send data, and  disconnect
to  a  DECnet-11M  system,  should  be  available no later than
January 22, 1979.

The following is the Unit Test Plan devised by  the  developers

      "The purpose of unit testing the  DN20  False  Node
      Init is to assure the implementors that:

      1.  "the code implements the algorithm outlined  in
          section  5  of  the  Addendum  to  the  TOPS-20
          Project Plan for DECnet-20;  and,

      2.  "the   algorithm    exhibits    the    external
          characteristics  identified in section 2 of the
Addendum to TOPS-20 Networks Project Plan for DECnet-20  Page 4

      "To this end, unit test consists of two phases.  In
      the   first   phase,   we   verify  that  the  code
      modifications  produce  the   desired   microscopic
      effects.   Testing  at  this  level is accomplished
      using artificial stimulus and  inspections  of  the
      system data structures.  Specific tests verify that
      the DN20 can:

      1.  "discriminate the DTE  line  from  other  lines
          during the line enable and startup sequence

      2.  "initially start  the  DTE  line  and  not  any

      3.  "send the 20xx its native node init message

      4.  "save the node init parameters  from  the  20xx
          system  and  not  save  parameters  from remote

      5.  "allow lines other than the DTE to  start  once
          the 20xx system completes node initialization

      6.  "correctly build node init  messages  which  it
          sends to remote nodes from the saved parameters
          provided by the 20xx system

      7.  "discriminate the DTE  line  from  other  lines
          when   messages   are  received  without  route

      8.  "detect control messages  other  than  start-up
          control messages

      9.  "build route headers for control messages which
          have  the  node  name of the 20xx system as the
          destination node  and  the  name  of  the  node
          adjacent  on  the  receive  line  as the source

      "In  the  second  phase,   we   verify   that   the
      combination  of  microscopic  changes  produce  the
      desired system performance.  This  is  demonstrated
      by the following events.

      1.  "The DN20 and the 20xx system complete the node
          init operation.

      2.  "The 20xx system and the DN20 communicate using
          any   program   that   uses  the  logical  link
Addendum to TOPS-20 Networks Project Plan for DECnet-20  Page 5

      3.  "The DN20 will not node  init  with  any  other
          (not 20xx) system until the 20xx completes node

      4.  "The DN20 will node init  with  another  system
          once    the    20xx   system   completes   node

      5.  "The remote system believes that  the  name  of
          the  adjacent  node  is  the  name  of the 20xx

      6.  "The 20xx system and a Phase  2  remote  system
          communicate  using  any  program  that used the
          logical link interface.

      7.  "The 20xx system and a remote system which does
          not  build  route headers communicate using any
          program that uses the link interface."

 3.2  System Test

 Once a system which has been unit tested is available, system
 test will start.  This will be January 22, 1979.  System test
 will consist of DECnet Certification Comprehensive  tests  as
 specified  in  the  DECnet-20 Version 2.0 Certification Plan.
 These tests will be run originally to the  DECnet-11M  system
 on SYS880.  It is expected that to successfully complete this
 first phase of  system  test  will  require  three  weeks  of
 testing  ending  February  9, 1979.  These tests will be done
 using the DN20 on 2102 stand-alone at  least  two  hours  per
 day.   Inability to obtain the use of the DN20 for these time
 periods will cause one-for-one slippage to this part  of  the

 After system  test  with  DECnet-11M,  system  test  will  be
 conducted  with a 2020.  This 2020 is currently planned to be
 system 4097.  This phase of system test is expected  to  move
 significantly faster, and require no more than two weeks, and
 most likely one week.  Planned  completion  is  February  16,
 1979.   As above, 2102 DN20 stand-alone time for at least two
 hours a day will be required.

 Once the above certifications have been completed in  a  DN20
 stand-alone  environment,  the  system  will  be put into the
 standard timesharing load test environment.
Addendum to TOPS-20 Networks Project Plan for DECnet-20  Page 6

 3.3  Load Test

 Timesharing Load Test is the next  phase  of  the  test  plan
 commencing  February 19, 1979.  The new DN20 code will be put
 onto 2102 as the standard  timesharing  system.   During  the
 load   test  period,  various  certification  tests  will  be
 completed to other 2040/50/60 systems, and to various  PDP-11
 based   DECnet   systems   as   specified  in  the  DECnet-20
 Certification Plan.

 The other, related aspects of network  load  test,  including
 ATS  and  RJE,  will continue according to original plans and
 schedules.  This addendum should  have  no  major  impact  on
 testing or functionality of these other projects.

 3.4  Field Test

 To enter Field Test, the "False Node Init" system  must  have
 passed  formal  certification  with  DECnet-11M  Version 2.0;
 DECnet-2020  Version  1.0;   and   whatever   DECnet   system
 DECnet-20  Version 2.0 will Field Test with, if not either of
 the former.

 Field Test will proceed as originally planned  with  the  new
 "False Node Init" system.


 The "False Node Init" algorithm has as its major goal  making
 the  2040/50/60  host  and DN20 front end appear to the other
 nodes of the network as one  non-intercept  node,  that  node
 being  the  host  node.   The  DN20  does  not  exist  in the
 knowledge of the network,  except  to  the  host  2040/50/60.
 That is:

 1.  The 2040/50/60  will  perceive  the  network  to  be,  as
     presently, front ended by the DN20 intercept node.

 2.  The DN20 will  special  case  certain  of  its  intercept
     functions as described later in this section.

 3.  All network nodes connected point-to-point with DECnet-20
     will  perceive  one  non-intercept end node with the node
     name and number of the 2040/50/60.   They  will  have  no
     knowledge  of  the  existence of an intervening node (the

 This will be accomplished in the following manner:
Addendum to TOPS-20 Networks Project Plan for DECnet-20  Page 7

 1.  There are no changes to the TOPS-20 system.

 2.  When the DN20 is first started, it will do  an  NSP  NODE
     INIT  with  the  DTE-20  line only.  This will be done as
     presently implemented.

 3.  The DN20 will use the NODE INIT message received from the
     host  TOPS-20,  use  the  minimal  values  of  BLKSIZ and
     SEGSIZE, and start the Node Init process with  all  other
     started  lines.  Note that this Node Init process is what
     causes end nodes to see only a  non-intercept  2040/50/60

 4.  When the DN20 system is originally built,  the  host  and
     DN20  passwords  must  be set equivalent.  The DN20 front
     end will continue to do all node verification.

 5.  Outgoing CONNECT INITIATEs (from the host  2040/50/60  to
     any  other  network  node) will be processed as presently

 6.  Incoming CONNECT INITIATEs (to the host  2040/50/60  from
     any other network node) will be processed as follows:
     a.) If a  RTHDR  (Routing  header)  exists,  it  will  be
     processed as presently implemented.
     b.) If a RTHDR does not exist, and  the  message  is  not
     from  the  DTE  line,  the  DN20  must generate a correct
     RTHDR,  setting  the  destination  node   to   the   host
     2040/50/60,  and  the  source  node  to the node known to
     exist on the incoming line.
     c.) If a RTHDR does not exist, and the  message  is  from
     the DTE, the message is for the DN20.

 7.  Data Messages on established logical links will  work  as
     currently implemented, using the LNKADR (Link address) to
     do the proper intercept functions.

 8.  All  other  NSP  Control   Messages   (not   Connect   or
     initialization messages) will be handled as specified for
     incoming CONNECT INITIATEs.

 Topologically, this algorithm makes DECnet-20 consistent with
 all other DECnet Phase II products.  It is an end node to end
 node, point-to-point system.

 [End of Addendum to Networks Project Plan]