J. Postel
IEN 160                                                              ISI
                                                         7 November 1980

              Internet Meeting Notes -- 7-8-9 October 1980


   The meeting was held at the Royal Signals and Radar Establishment in
   Malvern, England.  John Laws was the host.  Alan Fox gave a welcome
   to and explanation of RSRE.  John Laws described the arrangements.


   Vint Cerf described the objectives of the meeting.  The main points
   were to exchange information on the status of various projects, to
   discuss plans, and to review performance and design issues.


   A.  ARPA

      Vint reported on some changes in the ARPA IPT office.  People:
      (1) Dr. R. Kahn was married, (2) Col. J. Hammett is leaving the
      office for an assignment in Europe, (3) Dr. B. Leiner is joining
      the office to work on the Packet Radio Program, and (4) Lt. Col.
      Duane Adams is now Executive Assistant to the Director of IPTO.
      Equipment: Much of the equipment on the 7th floor will be moved to
      the 8th floor, the current 316 TIP  will be replaced by a C30 IMP
      plus 316 Terminal Access Mini-Host, the XGP will be replaced by a
      Penguin, and a RAPICOM 450 facsimile machine will be installed.

      An important goal for protocol implementations is to eliminate the
      use of NCP and completely switch over to TCP  by January 1983.

      ARPA is providing technical support to the National Science
      Foundation (NSF) in the planning  for a Computer Science Network
      (CSNET) to be operated by a consortium of Universities.
      L. Landwebber at the University of Wisconsin is the coordinator of
      the consortium.  The current plan is to use a combination of
      existing networks to provide the physical support for CSNET.

      ARPA intends that by the end of 1982 all existing 516 and 316 IMPs
      will be replaced by C30 IMPs.  The first few will go to (not in
      this order) SRI, MIT, ISI, ARPA, BBN, BRAGG, and Berkeley.

Postel                                                          [Page 1]

                                                                 IEN 160
Internet Meeting Notes

   B.  BBN

      Dale McNeill reported on the status of SATNET.  The PSP terminal
      provided by COMSAT has been installed and the SPADE terminal has
      been removed.  The ARPANET line 41 between NORSAR and SDAC  which
      is supported by a satellite is now using a military circuit and
      availability has been noticeably poorer.

      CATENET gateways attempt to split the load when routing
      information indicates two or more paths of equal cost.  This means
      that traffic from the UCL gateway over the SATNET to the ARPANET
      will be split between the BBN gateway and the NDRE gateway.  When
      it turns out that the ARPANET line 41 is down, half of the traffic
      goes into a black hole.  The NDRE gateway can talk to its IMP and
      so reports it is connected to the ARPANET, but the ARPANET is
      partitioned due to line 41 being down.  Due to this problem, it
      was agreed that communication between the NDRE Gateway and the UCL
      Gateway be permanently broken to avoid packet loss due to gateway
      load splitting when line 41 is down.

      There has also been an increase in the packets lost in SATNET due
      to an increase in the bit error rate which is due to satellite
      power being reduced by 1db since June 1st.

      Dale also reported that the VAN Gateway (an ARPANET-TELENET
      gateway) work has progressed to testing the Frame Level protocol.
      There seem to be some problems with the interface due to differing
      interpretations of X.25.  This gateway is implemented in LSI-11.

      Ginny Strazisar reported on the recent development for the
      Gateways.  The use of XNET has converted to version 4.  A problem
      with the Redirect  Message has been fixed.  The implementation of
      fragmentation has not been completed.

      A problem with reinitializing the UCL gateway was discussed.  It
      seems as if some combination of using XNET, the robustness card
      and LDSRV should be able to handle this case.  UCL, SRI, and BBN
      will investigate.

      Jack Haverty reported that new TCP implementations are now just
      beginning for the VAX Unix (v.7), the HP 3000, and the new TIP
      (mini-host attached to a the C30 IMP).  Design notes on these will
      be distributed as IENs.  A description of the performance
      measurement tools developed for DCA should be available about 1
      November.   A local net based on the Ungerman-Bass NET-ONE
      equipment is being tested.  A design for a TIP Login system is in
      progress.  A gateway between the RCCNET and the ARPANET and a

Postel                                                          [Page 2]

                                                                 IEN 160
Internet Meeting Notes

      local net based on C30s is being installed.  IEN 158 was issued
      which describes the XNET-4 protocol.

      David Flood Page reported that the CMCC log files are now
      primarily event driven and summaries are produced.  If you want to
      receive the daily statistics, send a message to David.  IEN 157
      was issued which discusses some new performance measurement CMCC
      message formats.


      Dave Mills reported on activities at COMSAT.  COMSAT is working on
      a revised version of INTELPOST which will use IP and TCP.  Dave
      described the configuration of equipment at COMSAT which consists
      of a number of small hosts, mainly LSI-11s.  This network uses the
      logical host field of the Internet Address to identify the host.
      Some bugs were found in some ARPANET hosts treatment of this
      field.  The local net protocol is IP.

      Dave has been particularly active in testing TCPs and IPs, and
      will discuss some of these issues in another session (see
      section V).  COMSAT has implemented programs to send and receive
      computer mail on the "playpen" host.  These are written in C.
      COMSAT has also used NIFTP to transmit files between their hosts
      and ISIE.  The NIFTP software was provided by UCL.  COMSAT and ISI
      have exchanged facsimile images.

      COMSAT plans to create a full CATENET gateway and to arrange a
      permanent connection to the ARPANET.


      Ed Cain reported on the status of the EDN.  Fragment reassembly
      has not yet been implemented.  The Host and IMPs have been
      converted to 96 bit leaders.  The gateway has implemented most of
      the CMCC measurements reports.  One problem is that many gateways
      and hosts do not have the EDN in their tables.

   E.  DOD

      Ray McFarland noted that Ken Shotting has done further work on a
      formal analysis of IP and a report will be forthcoming.

   F.  ISI

      Jon Postel reported on the installation of the PENGUIN laser
      printer and the communication of data to it via IP, UDP, and TFTP.
      The program that manages the input  and output of facsimile data

Postel                                                          [Page 3]

                                                                 IEN 160
Internet Meeting Notes

      has been modified to use either the new or old format.  Jon
      reported that the work on protocol verification is progressing and
      that Carl Sunshine may have a report at the next meeting.

      Jon also reviewed the IENs and RFCs produced since the last
      meeting.  Since the whole ARPANET is to convert to IP and TCP it
      is appropriate for protocol specifications and implementation
      related memos be RFCs while research and design related memos be

   G.  Linkabit

      Estil Hoversten noted that Linkabit recently merged with another
      company and will be setting up a private corporate satellite
      network.  Linkabit is doing the final testing of the ESI and
      expects send it to ISI in mid-October.  The expected review of ST
      protocol will not be presented.

   H.  LL

      Cliff Weinstein described the structure and status of the WBCNET.
      The initial four stations (LL, ISI, SRI, DCEC) all have their
      antennas installed.  Work is underway to bring the net into
      operation in the next few months.  LL is developing a local
      network called LEXNET, some digital voice terminals (VTs) and
      traffic emulator and traffic concentrator hosts.  An 11/45 is
      being programmed to be an WBCNET-LEXNET gateway.  This will be a
      ST gateway but not initially a full IP gateway.

   I.  MIT-LCS

      Dave Clark described the  complicated collection of networks and
      hosts at MIT.  There are several families of protocols in use and
      several interconnections.  Things are complicated enough that
      Corbito has been designated czar of networks at MIT.  Some things
      in progress are: Mail Service Programs, FTP programs, an NIFTP,
      X.25 interconnections for Telnet and Tymnet.  The  Nu machines are
      coming along; an IP for the Nu is being written.  Multics
      implements an Echo and Echo Reply to do PING with COMSAT.  MIT
      still needs an additional IMP port.  Interested in IP and TCP
      implementations for super small machines.


      Frank Deckelman noted the interest of the Navy Electronics
      Laboratories in the ARPA Internet.

Postel                                                          [Page 4]

                                                                 IEN 160
Internet Meeting Notes

   K.  NDRE

      Yngvar Lundh reported on the local net development at NDRE  which
      is based on protocol processors implemented on Z80s with 65 kb of
      memory.  Each processor has a kernel and a specialized module such
      as a speech packetizer, an LPCM, a TCP, or NVP.  The
      implementation language is PLZ.  A highly formalized graphical
      description language is being used to design the TCP.

   L.  RSRE

      Brian Davies reported on the activities at RSRE.  RSRE has been
      very active in measuring TCP performance and will report some
      results in another session.  Some suggestions for changes to IP
      and TCP are: (1) If the option code could indicate by a type or
      class bit if the option were to be copied or not on fragmentation
      things would be easier for the gateway; (2) also on fragmentation
      it might be better to break the datagram into equal sized
      fragments rather than a maximum sized fragment and the left over;
      (3) TCP should focus more attention on the critical impact of
      timeouts on performance, especially noting that different
      destinations may vary in round trip times by an order of

      The line between RSRE and UCL was recently upgraded to 4800 baud.
      RSRE particularly noticed the lost traffic due to the problems
      with line 41.

   M.  SRI

      Ron Kunzelman reviewed the status of the Packet Radio networks,
      and discussed a problem with terminal access from Ft. Bragg TIU
      users at ISID.  The normal TOPS-20 character-at-a-time remote echo
      seems to saturate the bandwidth available via TCP, the gateway, or
      the networks.  A line-at-a-time local echo mode has been developed
      to reduce the traffic load.

      Ron also described some modifications to ACC controllers for the
      1822-LSI11 interfaces:

         (1) 18 bit addresses
         (2) address incrementing
         (3) switch to tell (?)
         (4) cycle shortening
         (5) last bit on gather write
         (6) last input character
         (7) substitution of a part

Postel                                                          [Page 5]

                                                                 IEN 160
Internet Meeting Notes

      A PDP 11/44 has arrived.  This will run Unix (v.7) and will be
      used for a measurement host.  The antenna for WBC is installed,
      but some concern has been expressed about safety to passers-by.

      Jim Mathis reported that TIU's now do reassembly of datagram

      Holly Nelson described some new software development tools for use
      on UNIX.  Also noted that the Port Expander has all the features
      that were discussed at the last meeting.

   N.  UCL

      Robert Cole described the activities at UCL.  Fragmentation is
      implemented for sending datagrams and reassembly for incoming
      fragments.  Chris Bennett is developing a Unix based mail server
      based on MMDF and MH using TCP and IP for one underlying
      communication medium, and X.25 for another; there is also interest
      in interworking with CSNET for computer mail.  Steve Treadwell has
      developed some programs to decode and smooth facsimile data.

      A Cambridge Ring local network is being installed, but the
      protocols have not been chosen as yet.  Connections via X.25 to
      IPSS and EURONET are being tested.

      UCL has also been affected by the poor availability of SATNET.

      Ron Jones presented measurements on Port Expander and 1822
      interface performance.  The maximum achievable packet rate through
      the PE from a source to a sink was 65 pkts/sec (with the source
      and sink directly connected the rate was 255 pkts/sec).  The 1822
      interface performance was found by looping packets of various
      sizes through the PE.  The interface bit rate for a PI interface
      connected to a DMA interface was 71 kbits/sec and for two DMA
      interfaces was 325 kbits/sec.  The latter experiment also yielded
      5.7 ms as the time for the PE to switch a packet.

Postel                                                          [Page 6]

                                                                 IEN 160
Internet Meeting Notes


   A.  Internet Name Server

      SRI is developing an internet name server consistent with the
      specification in IEN 116. It was expected to be demonstrable at
      this meeting.  The development has not reached such a state and
      this item is deferred until the next meeting.

   B.  Interim Internet Mail System

      ISI is developing a prototype mail program for supporting text
      mail in the internet and between NCP and TCP hosts.  It was
      expected to be able to demonstrate these programs at this meeting.
      The design of these programs has only recently been developed (see
      section XII).  This item is deferred until the next meeting.

   C.  FTP and MAIL Memo

      ISI has produced a memo on text mail for the Internet.  It is
      RFC 772.  RFCs 771 and 773 offer motivation and discussion of this
      approach (see section XII).

   D.  IP and GGP Error Report Memo

      ISI was to produce a memo on error handling in IP and GGP.  This
      was not done and this item is continued to the next meeting (see
      section XV).

   E.  XNET Specification

      BBN has produced a memo on the XNET protocol.  It is IEN 158.


   Dave Mills reported on the sessions for testing the fragmentation and
   reassembly implementation in the IP protocol modules.  The results
   indicate that such testing is useful in that a few problems were
   found and corrected, but disappointing in that a number of hosts and
   gateways don't implement fragmentation as yet.


   Dave Mills discussed some performance problems with networks composed
   of low speed lines (e.g., 1200-1900 baud) and small hosts with
   minimal buffers.  In such "tiny pipe" networks, attention must be
   paid to the performance effects of TCP segmentation decisions,
   acknowledgment strategy, window strategy, and retransmission timeout

Postel                                                          [Page 7]

                                                                 IEN 160
Internet Meeting Notes

   selection.  These performance parameters must be chosen with respect
   to the partner at the other end of the TCP connection.  For example,
   a connection between a tiny host in a tiny net and a large host in a
   large net (e.g., the playpen in COMSAT net and ISIE in ARPANET) has
   very different characteristics than connections between roughly equal


   Zaw-Sing Su presented a detailed description of some measurement

   The aspects of performance measurement can be identified as follows:

      Artificial Traffic Generation
      Data Registration
      Data Collection and Transport
      Experiment Preparation and Control
      Data Reduction and Presentation
      User Interface

   Measurements could be made at several levels:

      TCP Performance
      TCP Analysis
      IP Performance
      IP Analysis
      Internet Component Performance

   Where performance is as perceived by the user and analysis is by

   The types of things studied in performance measurements are:

      Traffic Arrival and Departure Statistics
      Throughput and Delay Performance

   The types of things studied in analysis measurements are the
   mechanism used by the protocol.  For TCP:

      Relative data efficiency
      Retransmission sent and received
      Out of order arrivals
      Ack Only segments
      Ack Delay
      Zero Window periods

Postel                                                          [Page 8]

                                                                 IEN 160
Internet Meeting Notes

   For IP:

      Fragmentation and Reassembly statistics
      Use of options statistics

   For GGP:

      Routing Decisions
      Congestion Statistics

   Zaw-Sing suggested an internet delay measurement capability to be
   implemented as an optional header field for both TCP and IP.

   The TCP option would have source and a destination timestamps of 32
   bits each plus the option code and length octets for a total length
   of 10 octets.  The time would be in milliseconds.

   The IP option would have the type and length octets, a 16 bit id, and
   N stamps, where each stamp is a 32 bit IN address and a 32 bit time
   (in milliseconds).  The maximum number of stamps would be 4 due to
   the limitations on the header size.

   Questions were raised about combining this option with the
   Source-Route or Return-Route options.

   The consensus seemed that rather than an option in the IP header the
   timing data ought to be accumulated in the data part of the datagram
   in a protocol like GGP.


   Bruce Hitson discussed the need for one-way delay measurements in the
   Catenet.  It was stressed that these measurements would be
   particularly critical for performance measurement in an internet
   environment.  The very large physical distances involved and the
   non-participatory (at least in performance measurement) nature of the
   member networks are examples of why one-delays would be very useful.
   Round trip measurements are of questionable value since the network
   may change quite a bit during the course of a single round trip (up
   to 10 seconds in some cases).  To be able to make one-way delay
   measurements, synchronized clocks are needed.

   Bruce described several clever ways of synchronizing clocks with
   third party time sources.  The best choice seeems to be some devices
   that listen to a radio station (i.e., WWVB in the United States) and
   have a computer interface (e.g., RS 232) to report the time to the
   computer on request.

Postel                                                          [Page 9]

                                                                 IEN 160
Internet Meeting Notes

   ISI (as noted in the notes of the last meeting) has already ordered 4
   such devices for use in WBC and CATENET measurements.  Design of
   experiments that will make use of these devices is being considered.
   For further details, see Appendix  B.


   Jim Mathis reported the results of some round trip measurements made
   using the LDSRV program.  A round trip in the ARPANET between
   DARCOM-KA and the Ft. Bragg Gateway took about 600 ms.  Similar
   measurements between DARCOM-KA and a host in a local PRNET took 170
   ms., and between DARCOM-KA and a host in the Ft. Bragg PRNET took 800
   ms.  For further details see Appendix C.


   Brian Davies discussed some suggestions for performance improvements
   based on the experience at RSRE.

   The use of an adaptive retransmission timeout seems to be very
   helpful.  RSRE has experimented with one based on the following:

      1.  For each segment record the sequence number and time sent.

      2.  For each acknowledgment determine the round trip time (RTT) of
      the sequence number thereby acknowledged.

      3.  Compute an Integrated Ack Time (IAT) as follows:

         IAT = ( ALPHA * IAT ) + RTT

      4.  Compute a Retransmission Time Estimate (RTE) as follows:

         RTE = Min [ BOUND, ( BETA * IAT ) ]

            Where BOUND is an upper bound on the retransmission time and
            BETA is an adjustment to the IAT to account for variation in
            the delay.

   RSRE currently uses  ALPHA = 31/32 and BETA = 1.33.

   [Dave Clark noted that MIT-MULTICS uses the same algorithm but with
   ALPHA = 4/5 and BETA = 1.5.]

   Brian presented some graphs of the actual RTTs and resulting RTE for
   TCP connections between  RSRE and ISIE.

   Andy Bates  presented data from recent measurements of double round

Postel                                                         [Page 10]

                                                                 IEN 160
Internet Meeting Notes

   trip times between RSRE and UCL, BBN Gateway, and ISIE.  There are
   two aspects of the measurement to be explained:  The absolute delay,
   and the variation in delay.  The absolute delay (for the least
   delayed packets) seems to be in agreements with the expected delay
   given the speed of the lines, the protocols used, etc.  For example,
   one second time for a separate reservation is required (which is the
   current strategy).  The variation in delay is not yet satisfactorily
   explained.  Some arises in SATNET, and a good deal arises in the
   ARPANET.  One suggestion (by Danny Cohen) is that if the packets are
   far enough apart in time then new Source IMP to Destination IMP
   reservations are needed for each packet, this could add a large
   variable delay.

   A goal for the next meeting is to figure out the cause of the
   variation in the delay.


   Mike Wingfield discussed the standards work on protocols sponsored by
   NBS.  Mike first noted that many standards groups are actively
   working on standards in the communications area.  The work NBS is
   sponsoring at BBN is to develop service specifications, feature
   analysis, formal specification, and a test implementation for a
   transport protocol.

   BBN has developed a formal description language which is an extension
   of a finite state machine description.  The language is entirely
   textual and so can be easily manipulated with computer tools.

   The basic element is a transition description which is composed of a
   next state, a current state, an event, and a procedure.  The
   procedure is written in "C".  The following tools for working with
   the language have been developed: a syntax checker, a state checker,
   a special editor, and a test generator.

   Additional work involves a feature analysis of X.75, IP, and PUP as
   internet protocols.  NBS is also interested in the ECMA proposal for
   a Transport Protocol and BBN is analyzing it.


   Vint Cerf described the problem arising in the exchange of computer
   mail between old NCP only hosts and new TCP only hosts.  The plan is
   to provide relay or forwarding hosts that implement both transport
   protocols and relay the mail.

   Jon Postel explained some of the details of this plan.  A key
   decision is to provide a new MAIL SERVER and a new mail protocol.

Postel                                                         [Page 11]

                                                                 IEN 160
Internet Meeting Notes

   These will be very similar to the existing protocols and servers but
   will have an important new feature:  the address passed in the MAIL
   command will include the destination host as well as the user.

   Jon also discussed the need for hosts to add to their host tables
   some indication of the status of each other host: old table NCP, new
   table NCP, or TCP (all TCP hosts are to have new tables).  These
   three kinds of host mean there are 9 combinations of mail exchange.
   These were discussed on a case by case basis.  The difficult case was
   the old NCP host to the TCP host.  In this case a relay host could
   receive the mail using the old mechanisms but would have no idea of
   which host to forward it to.  One proposal is to have a list of
   registered users available to this relay host.

   Vint also discussed the idea that the hosts have unique indentifiers
   independent of network, and even that organization names could be
   used instead of host names.

   The discussion indicated some doubts about the practicality of
   registered users, especially in resolving name conflicts now resolved
   by host names.  Also, concern was expressed about the globally unique
   host names.

   RFCs 771, 772, and 773 present the plan, the mail protocol, and a
   discussion of the issues.  Comments are solicited.


   Danny Cohen discussed routing to avoid undesirable networks or to
   limit a route to known networks.  The existing source routing option
   may be called loose source routing (LSR) since it allows the gateway
   to send the datagram on any route they choose between the specified

   Danny proposes another option called strict source routing (SSR),
   which is like LSR except that a gateway may only route a datagram to
   the next specified address through the network specified in the NET
   part of that address.

   This is very restrictive and would highly control the route.  It
   would also provide a way to route things out of one network, through
   a second network, and back into the first network, to get around a
   partition or use special transmission capabilities.

   Vint Cerf proposed an alternative of simply a list of acceptable
   networks.  This would be less restrictive, but might lead to problems
   in routing.

Postel                                                         [Page 12]

                                                                 IEN 160
Internet Meeting Notes

   Danny's proposal is described in IEN 156.


   Dave Clark discussed some problems in IP and TCP implementation in
   the MIT environment.

   One situation is that several hosts at MIT are on two or more
   networks, and have as many internet addresses.  The problem is that
   while one interface is down, the host and the other interface may be
   up, but datagrams sent to the down interface address will be
   discarded rather than routed to the other interface address.

   Dave presented a scheme that would allow a two-connected host to
   avoid this problem with the help of nearby gateways.  The gateways in
   the networks the hosts is connected to would have tables to map a
   special form of address into one of the regular address and to choose
   between regular addresses based on knowledge of which interfaces were
   up.  The hosts sending to the two-connected host would always send to
   the special address.

   This scheme was not well received.  The consensus seemed to be that
   it was too specialized and involved too much special case mechanisms.
   It is agreed to be an important problem, but a better solution is

   Another situation involves very small hosts and the desire to
   implement TCP in them.  For example, a TCP in 2K bytes of memory.
   What corners can be cut?  For example, no data with SYN or FIN,
   simple ACK and window policies.

   One suggestion is for an option to specify a maximum receive segment
   size to be sent only with a SYN.  This would have different effects
   than a consistently small window because it may allow many segments
   to be in transit at a time even though each is small.  The consensus
   seemed to be that this was a good idea.


   Jon Postel reviewed the discussion from the last meeting of error
   reporting in IP and GGP.  They are different in that in IP an option
   is used and in GGP the data area is used to carry the error
   information.  They are redundant in that most of the errors mentioned
   in IP are also mention in GGP.

   Jon proposed to put all these error reports into a new protocol and
   use a GGP style mechanism.  The consensus seemed to be that we should
   continue to use GGP, and eliminate the IP error option.

Postel                                                         [Page 13]

                                                                 IEN 160
Internet Meeting Notes


   The next meeting will be hosted by ISI and will be held 28-29-30
   January 1981.  Attendance will be limited so if you plan to attend
   please clear that with Vint Cerf (CERF@ISIA). and notify Victor Brown
   (BROWN@ISIF).  Jon Postel will be the host.

   A tentative schedule for subsequent meetings is: May 81 at COMSAT,
   September 81 at UCL, January 82 at SRI, May 82 at BBN, and September
   82 at IABG/DFVLR.


      1.  Provision for source routing in the interface between TCP and
      IP and in the TCP tables.  How will the reverse route information
      be handled?

      2.  Further discussion on internet mail transition.  Focus on
      alternatives to the unique name requirement which led to potential

      3.  More on performance observations within the Catenet, in the

      4.  MITRE report on their new 350 kb/s TCP that runs in a Z-8000.

      5.  Front-ending of TCP/IP.

      6.  Progress reports on FTP where ever it is being implemented.

      7.  Progress reports on the (interim internet) message system.

      8.  Progress reports on the protocol verification. ISI, BBN, SDC,
      and DoD.

      9.  Discussion of "worm" programs, XEROX.

      10.  Discussion of the IIN problem, the inter-inter-net.  How and
      at what levels can we interoperate with other nets?

      11.  Report on On-Tym and Telemail relative to ARPANET mail and
      Internet Mail.


      1.  New text for the TCP and IP specification changes.

Postel                                                         [Page 14]

                                                                 IEN 160
Internet Meeting Notes


   The third day of the Internet Meeting was a seminar on the TCP/IP and
   Yellow Book approaches to internetting.  The following notes are
   provided by Brian Davies of RSRE.


      John Laws started the informal Seminar by giving some background
      as to its genesis: namely that with so many TCP/IP experts having
      come to the UK and it being the case that the UK public network
      users are promoting an apparently competing solution, then it
      seemed an ideal opportunity for parties to exchange views.  It was
      not expected or intended that there should be any dramatic
      conversions of the parties vis-a-vis datagram and virtual call
      issues.  However, it was hoped that areas of common approach might
      be identified even though expressed in a different language.  In
      addition, the reasons for divergence might be mutually identified
      and appreciated.

      An "impartial" Chairman, Derek Barber (Microprocessor Applications
      Project, Dept. of Industry) was introduced.  Many presentations of
      views were scheduled and firm discipline, of both presenters and
      the audience, was administered by the Chairman.  A summary of
      presentations and ensueing discussion follows.


      The user requirement for communications in a typical air defence
      scenario was presented.  The data communications were provided by
      a common bearer network and mobile tactical networks of the JTIDS
      type.  The data-bases and their functions were described to
      illustrate why they were distributed.  The mobility of the users
      not only in a single net but across multiple tactical nets was
      emphasized with particular reference to the problems of
      maintaining connections to their associated databases.

   Peter Linington (Data Communications Protocol Unit, Dept. of

      To ensure that the parties to the debate were speaking a common
      language a set of "basic" and "obvious" axioms for internetworking
      were presented.  The properties of a global transport service were
      described.  Compatability for internetworking would be achieved by
      enhancing each underlying network to the common transport service
      standard.  This enhancement would be within hosts and gateways;
      the enhancement being achieved by encapsulation of the specific

Postel                                                         [Page 15]

                                                                 IEN 160
Internet Meeting Notes

      network features within appropriate network specific protocols.
      Thus only the service attributes have to be agreed globally; hosts
      only have to implement their local network enhancing protocols;
      gateways at worst have only to implement neighbour network
      enhancing protocols.

   (Computing Centre, Cambridge University).

      The point was made that diverse network address naming authorities
      will always exist and will always assert their techinical need to
      be different.  A naming and addressing mechanism appropriate for
      this environment was described.  This featured use of an "address"
      string whose component parts are addresses, titles, generic names.
      Traversal of connected networks was driven by successive
      "activation", with possible address/title
      expansion/transformation, of the component parts appropriate to
      the current address/naming domain: in effect akin to source
      routing.  In particular, the use of titles/generic names allowed
      the user to be unconcerned with changes in remote network
      addresses or interconnection architectures.  Depending on the
      name/address conventions of the neighbour networks, gateways would
      be required to have varying degrees of intelligence about
      name/address mappings.

   (National Physical Laboratory).

      Vince detailed his varied and long experience of implementing and
      working with protocols in an internetworking environment.  This
      environment had gateways to both datagram and virtual call
      networks.  Both approaches had used hop-by-hop techniques for some
      of the levels of protocols.  In addition one gateway also passed
      high levels of protocol transparently.  Neither approach could be
      declared as "better".  The community of users associated with each
      of the external networks had different requirements and this had
      significantly determined the internetworking solutions.  In
      analogy, domestic cars were ideal for many transportation
      requirements, but there are times when the virtues of tanks are

   Chris Bennett (UCL)

      In order to incorporate an existing network into the Yellow Book
      framework, a 'Yellow Book protocol' must be defined locally to
      that network which builds on the existing network interface to
      bring it in line with the Yellow Book service.  In the Catenet,

Postel                                                         [Page 16]

                                                                 IEN 160
Internet Meeting Notes

      the appropriate starting point is TCP which already offers the
      basic virtual call interface.  The data stream is structured into
      arbitrary length data and control messages.  Each control message
      is allied with TCP actions, where possible, to gain the
      appropriate effect.  The TCP-based Yellow Book protocol is not
      complex and is mostly required to allow the transmission of
      connection information beyond the Catenet.  Details may be found
      in IEN 154.

   A USER REQUIREMENT FOR STANDARDS - Ken Heard (Joint Networks Team,
   Science Research Council, Rutherford Labs.).

      Background was given as to some of the functions/responsibilities
      of the Joint Network Team; this being advising/aiding the
      selection/implementation of an architecture and protocols for
      internetworking between diverse networks sited at UK Universities
      and Research Establishments.  The point was made that the
      productive functioning of this internetworking in the immediate
      future was urgent and, that time and resources could not be wasted
      on re-inventing the wheel.  Hence the adoption and rapid
      implementation of protocols emerging as "interim" standards for
      use on the UK PTT public network.  A review of
      protocol/architecture standardisation activities within
      national/international bodies (AFNOR, BSI, CCITT, ECMA, ISO,
      NBS,...) was given.  As a final comment attention was drawn to the
      influence on standards of the pioneering research networks such as
      ARPANET and the European Informatics Network.


      The wide range of diverse network implementations and environments
      incorporated in the ARPA Catenet was described.  The ARPANET
      itself, packet radio networks, broadcast packet satellite
      networks, and a variety of local networks all interwork using IP
      as the universal protocol.  Some of the experiments and
      demonstrations conducted were discussed.


      The architecture of the ARPA Catenet protocol family was briefly
      described and the services provided by the IP and by the TCP were
      described.  The  point that both protocols are available to the
      users  and can be used to build very different kinds of
      applications was emphasised.

   END-TO-END VS HOP-BY-HOP - Danny Cohen (ISI).

      The difficulty of building effective communication systems by

Postel                                                         [Page 17]

                                                                 IEN 160
Internet Meeting Notes

      relying on plug-to-plug compatibility on a hop-by-hop basis was

   SUMMARY OF ISSUES - Brian Davies (RSRE)

      The advantages of harmonization of transport protocols in the
      civil and military fields were presented.  However, the
      differences in emphasis in the user requirements would probably
      preclude this standardization in the foreseeable future.  These
      differences included availability of resources in the face of
      threat, mobility of users, and the military requirement to
      accommodate a dynamically changing internet topology.  In
      addition, the relative importance and costs of such properties as
      security, precedence and survivability had to be considered.  Some
      of the particular architectural issues involved in the Yellow Book
      and TCP/IP approaches were then presented.  In particular the
      implications of the addressing strategies, connection control and
      economies of use were highlighted.


      The initial discussion was used by a number of the presenters to
      clarify facts or points they had made in their talks.  The
      following paragraphs are a selection of the varied topics

      a)  The number of "grades" of service that might be required was
      discussed.  In the YBTS approach it had been identified that the
      one grade of reliable connection-oriented service was a
      requirement overwhelming all others.  In contrast, the TCP/IP
      approach had identified a need fo a number of distinct "grades" of
      service to be realized by specific protocols (e.g. speech, user
      datagram etc.).

      b)  Discussion showed that different emphasis of requirement had
      significant influences on the two architectures.  The more
      commercial environment within which the YBTS has been formulated
      places great emphasis on the economic use of resources.  However,
      the problems involved in maintaining connections across vulnerable
      or unreliable networks was an aspect not deeply considered within
      YBTS.  The TCP/IP approach had given much greater attention to
      this military aspect.  The two approaches could be seen to be
      non-competitive as they are solving different problems.

      c)  The YBTS approach to addressing is based on the premise that
      all networking authorities will not agree to a global addressing
      strategy.  The global addressing approach of the TCP/IP would seem
      to be in-line with the ISO recommendation on this issue.

Postel                                                         [Page 18]

                                                                 IEN 160
Internet Meeting Notes


   ISI is evaluating an absolute time clock for network measurement use.
   The clock is actually a radio receiver which is tuned to National
   Bureau of Standards station WWVB, which broadcasts on a frequency of
   60kHz, and is located at Fort Collins, Colorado.  WWVB provides both
   time and frequency information and its coverage area is effectively
   the continental United States.

   The clock is the Model 8170, made by Spectracom Corporation, 320 N.
   Washington St., Rochester NY 14625.  The 8170 is a rack-mountable
   unit, 17" wide by 5.25" high by 13.5" deep. Line power is 115/230
   volt 50 or 60 Hz AC at 60 watts.  An external antenna is required,
   which is a ferrite loop antenna in a tubular plastic housing 14.8"
   long and 2.7" in diameter with a threaded fitting in the center which
   accepts a standard 1" threaded plumbing pipe (for mounting purposes
   only).  The antenna is connected to the clock receiver via 50 ohm
   (RG58) coaxial cable with BNC connectors on the ends.

   For best accuracy, the antenna should be placed outside just above
   rooftop level (like a TV antenna).  However, an inside location near
   a window facing Fort Collins may turn out to be acceptable.

   Overall accuracy is specified as plus or minus (.1 millisecond +
   noise uncertainty + propagation delay setting error), where noise
   uncertainty is expected to be less than plus or minus .5 millisecond
   worst case.  This accuracy should be more than sufficient for network

   Time is output via a front-panel display (hours,minutes,seconds) and
   an RS-232 (D-15) jack on the rear panel.  Also output on the back
   panel is a 1Hz, 10% duty cycle TTL signal called the "on time" pulse.
   The leading edge of the on time pulse occurs at the beginning of each
   second.  In addition, a 1MHz standard frequency output is available
   on the back panel, which is a 3.4V rectangular positive pulse
   designed to drive a 93 ohm load, but which will drive a 50-ohm load
   with reduced amplitude.  This 1MHz output is phase-locked to the WWVB
   carrier, and can be used for calibrating counters with high accuracy.

   The user requests the time by sending the clock an ASCII capital "T".
   When it receives the "T", the clock waits until the start of the next
   second, and sends back an ASCII string containing the time. The
   rising edge of the start bit of the first character in the string
   occurs within a few microseconds of the rising edge of the on time

Postel                                                         [Page 19]

                                                                 IEN 160
Internet Meeting Notes

   The time string is structured as:


         I      =space if time synch lamp is on,
                 ? if time synch lamp is off
         DDD    =Julian day of the year (000 to 366)
         HH     =hours
         MM     =minutes
         SS     =seconds (at the start of this typeout)
         XX     =time zone setting with respect to UTC
                 (formerly called GMT).  EST is 05, PST is 08.

   The RS-232 port on the clock runs at a baud rate of 300 baud.

   The synch lamp on the front panel will be lit if the time can be
   expected to be reliable within plus or minus 1 millisecond.  The
   clock contains an internal 1MHz oscillator which is kept synchronized
   to WWVB.  If the WWVB carrier is lost, the internal oscillator will
   keep running, and accuracy to plus or minus 1 millisecond will be
   maintained for about 10 minutes, at which time the synch lamp will be
   turned off, although the oscillator keeps running.

   The back panel also contains thumb wheel switches for time zone
   setting, propagation delay setting, and a leap year switch.  Yes,
   Virginia, a leap year switch.  The purpose of the leap year switch is
   to maintain the day count properly if the WWVB carrier is lost near
   midnight of Dec. 30 (on a leap year) or Dec. 31 (on other years).

   Price is $2600 for the clock itself, $190 for the loop antenna, and
   $35 for a rack mount kit.


   The numbers were average round-trip times calculated by the LDSRV.
   Each number is the average RT time seen during the load operation,
   which takes about 350 or so packets.  RT times are not calculated for
   packets that are retransmitted.

   The average RT time to ARPANET hosts on the same IMP is around 70
   msec. There were some times somewhat less and a few a bit more.  To
   MIT, the usual average RT time is about 450 msec.  To the Ft. Bragg
   PE or gateway, the smallest average RT time is 600 msec.  The largest
   average RT time was 1.2 sec.

   The usual average RT time to SRI PRNET TIUs is 170 msec.  The
   smallest time was not less that 100 msec and the largest is 400 msec.

Postel                                                         [Page 20]

                                                                 IEN 160
Internet Meeting Notes

   To Ft. Bragg PRNET TIUs, the smallest average RT time is a bit more
   than 600 msec.  The usual RT time is around 800 msec and average RT
   times as large as 2.1 sec have been recorded.  Most of the loads had
   average RT times less that 1.1 sec.

   In the graphs, the y-axis is the number of loads in which the average
   round trip time was within the time bucket.

   ARPANET Hosts

      |XX          XX
      |XX          XX XX
   10-+XX          XX XX
      |XX XX       XX XX
      |XX XX       XX XX
      |XX XX    XX XX XX XX XX XX
      |XX XX    XX XX XX XX XX XX    XX XX
   0 -+------------------------------------
      0   .2    .4    .6    .8    1.0  1.2  secs

   SRI PRNET Hosts

      |   XX
      |   XX
      |   XX
      |   XX
   10-+   XX
      |   XX XX
      |   XX XX
      |   XX XX
      |   XX XX XX
   0 -+------------------------------------
      0   .2    .4    .6    .8    1.0  1.2  secs

Postel                                                         [Page 21]

                                                                 IEN 160
Internet Meeting Notes

   Ft. Bragg PRNET Hosts

      |                  XX
      |                  XX
      |                  XX
      |                  XX
   60-+                  XX
      |                  XX
      |               XX XX
      |               XX XX
      |               XX XX
   40-+               XX XX
      |               XX XX XX
      |               XX XX XX XX XX
      |               XX XX XX XX XX
      |               XX XX XX XX XX
   20-+               XX XX XX XX XX
      |               XX XX XX XX XX
      |               XX XX XX XX XX
      |               XX XX XX XX XX XX XX          XX    XX
      |               XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX
   0 -+--------------------------------------------------------------
      0   .2    .4    .6    .8    1.0  1.2   1.4   1.6   1.8   2.0 secs

Postel                                                         [Page 22]

                                                                 IEN 160
Internet Meeting Notes


   Author     Subject                                  Number
   -------    ------                                   ------


   Postel     Internet Meeting Notes - 14 & 15 May 1980   145
   Perlman    Flying Packet Radios and Network Partitions 146
   Perlman    Utilizing Internet Routes as Expressways    147
                        Through Slow Nets
   Postel     Telnet Protocol Specification               148
   Postel     File Transfer Protocol Specification        149
   Plummer    TCP JSYS Calling Sequences                  150
   Cerf       Final Report of the Stanford University     151
                TCP Project
   Cerf       DoD Protocol Standardization                152
   Bennett    Realization of the Yellow Book Transport    153
                Service Above TCP
   Bennett    Realization of the Yellow Book Transport    154
                Service Above TCP (supersedes IEN 153)
   Bennett    The Yellow Book Transport Service:          155
                Principles and Status
   Cohen      Controlled Routing in the                   156
                Catenet Environment
   Flood Page CMCC Performance Measurement
                 Message Formats                          157
   Haverty    XNET Formats for Internet Protocol          158
                Version 4


   Postel     Internet Protocol Handbook TOC              766
   Postel     Structured format for Multimedia Mail       767
   Postel     User Datagram Protocol                      768
   Postel     RAPICOM 450 Facsimile Format                769
   Postel     Assigned Numbers                            770
   Cerf       Mail Transition Plan                        771
   Sluizer    Mail Transfer Protocol                      772
   Cerf       Comments on the NCP/TCP                     773
                Mail Service Strategy
   Postel     Internet Protocol Handbook TOC              774

Postel                                                         [Page 23]

                                                                 IEN 160
Internet Meeting Notes


   Name                 Affiliation  Nationality   Mailbox
   ----                 -----------  -----------   -------
   Vint Cerf              ARPA        USA          Cerf@ISIA
   Don Allen              BBN         USA          Allen@BBND
   David Flood Page       BBN         British      DFloodPage@BBNE
   Jack Haverty           BBN         USA          JHaverty@BBND
   Bruce Hitson           BBN         USA          BHitson@BBND
   Dale McNeill           BBN         USA          DMcNeill@BBNE
   Virginia Strazisar     BBN         USA          Strazisar@BBNA
   Mike Wingfield         BBN         USA          Wingfield@BBND
   Gustav Fickenscher     BWB.MoD     Germany      ---
   Hoi Chong              COMSAT      Rep. China   Chong@ISIE
   Dave Mills             COMSAT      USA          Mills@ISIE
   Ed Cain                DCEC        USA          Cain@BBNB
   Hans Dodel             DFVLR       Germany      ---
   Helmuth Lang           DFVLR       Germany      ---
   J. Majus               DFVLR       Germany      ---
   Gerry Amey             DND/CANADA  Canada       ---
   Ray McFarland          DoD         USA          McFarland@ISIA
   Romy Fratilla          ELEX        USA          Deckelman@ISIA
   Horst Clausen          IABG        Austria
   Danny Cohen            ISI         USA          Cohen@ISIB
   Jon Postel             ISI         USA          Postel@ISIF
   Cliff Weinstein        Lincoln Lab USA          cjw@LL-11
   Estil Hoversten        Linkabit    USA          Hoversten@ISIA
   Dave Clark             MIT         USA          Clark@MIT-Multics
   Frank Deckelman        NAVELEX     USA          Deckelman@ISIA
   Oyvind Hvinden         NDRE        Norway       Oyvind@DARCOM-KA
   Yngvar Lundh           NDRE        Norway       Yngvar@DARCOM-KA
   Paal Spilling          NDRE        Norway       Spilling@SRI-KL
   Vince Hathway          NPL         British      ---
   Andrew Bates           RSRE        British      T45@ISIE
   Trevor Benjamin        RSRE        British      T45@ISIE
   Brian Davies           RSRE        British      T45@ISIE
   Roger Edwards          RSRE        British      T45@ISIE
   Alan Fox               RSRE        British      T45@ISIE
   Silvia Giles           RSRE        British      T45@ISIE
   John Laws              RSRE        British      T45@ISIE
   Paul Masterman         RSRE        British      T45@ISIE
   Jo Penley              RSRE        British      T45@ISIE
   Gill Roberts           RSRE        British      T45@ISIE
   Ron Kunzelman          SRI         USA          Kunzelman@SRI-KL
   Jim Mathis             SRI         USA          Mathis@SRI-KL
   Holly Nelson           SRI         USA          HNelson@SRI-KL
   Zaw Sing Su            SRI         Canada       ZSu@SRI-KL

Postel                                                         [Page 24]

                                                                 IEN 160
Internet Meeting Notes

   Chris Bennett          UCL         British      UKSAT@ISIE
   Robert Cole            UCL         British      UKSAT@ISIE
   Ron Jones              UCL         British      UKSAT@ISIE
   Steve Treadwell        UCL         British      UKSAT@ISIE

Postel                                                         [Page 25]