Aminet 4/Aminet 4 - November 1994.iso/aminet/comm/net/anos_2_9i.lha/AmigaNOS/TCPIP/Digger/DataBase.lzh/AMPRNews.105

Text File | 1992-06-23 | 16KB | 372 lines

                   AMPRNET TCP/IP Newsletter


                      Mike Chace - G6DHU

               Issue 5 Volume 1 - September 1991


  1.  This Month

  Welcome  to  issue  5  of  this newsletter for the UK TCP/IP
  community.  If you are a beginner in the world of TCP/IP  or
  perhaps  considering  taking  the 'plunge' then perhaps this
  will be of interest to you!

  If you are a more experienced  user  reading  this  for  the
  first  time, then hello, and I hope you'll find something of
  use too.

  This month's topics are :-

       2. IP Addressing
       3. Software News
       4. Network News
       5. Tutorial - Datagrams and Virtual Circuits
       6. 221 Closing


  2.  IP Addressing


  2.1.  Background

  Just as all radio amateurs worldwide can  be  identified  by
  their   unique   callsign,  TCP/IP  users  can  be  uniquely
  identified by their IP address.  IP (the Internet  Protocol)
  being  the  protocol used for routing packets amongst TCP/IP
  users.  IP works out where to send  packets  amongst  TCP/IP
  users  by  using  the  IP  address just like for instance, a
  NET/ROM node uses the callsign of a distant node to identify
  where to send packets.

  IP addresses are also coordinated  worldwide,  with  a  huge
  address  database  being held on computers at the University
  of California at San Diego  (UCSD).    This  database  holds
  details  of  everyone  (and  everything)  that  uses  an  IP
  address.  These users form a network (called the Internet).

  When blocks of addresses were being  allocated  to  specific
  types  of  IP users, Radio Amateurs were also allocated some
  of these.  The resulting  Radio Amateur 'Internet' is  known
  as the AMPRNET - AMateur Packet Radio NETwork.


  2.2.  What is an address ?

  Well,  now I've explained a little background to the subject
  of addressing within TCP/IP, I suppose I'd better  show  you
  what one looks like.

  All Internet addresses are 32 bit numbers.  That's all!  The
  standard  way  of  writing  an address is to write it as the
  decimal equivalent of the 4 bytes that make up the  address.
  For example my address would be written as

           44.131.20.3

  As  you  can  guess, the point of writing addresses this way
  (apart from making them more humanly readable) is to  convey
  some extra information about the address.  AMPRNET addresses
  can be broken down as follows :-

               44  = AMPRNET
               131 = UK
               20  = Geographical Region 20 (in UK)
               3   = The third address issued in region 20

  As you can see, AMPRNET was allocated the block of addresses
  from 44.0.0.0 to 44.255.255.255 so everybody in the Internet
  knows that  44  corresponds  to  an  AMPRNET  address.   The
  AMPRNET address coordinators chose to  split  the  block  of
  addresses  between  countries  and  so  the UK has addresses
  44.131.0.0 to 44.131.255.255. Furthermore,  the  UK  address
  coordinators  chose  to split UK addresses on an RSGB region
  basis which as you will  see  below  correspond  roughly  to
  three counties.    It's  all very hierarchical as you can no
  doubt  appreciate.

  There are lots more aspects to IP addressing  not  mentioned
  here  (such  as  network  classes) but I hope the discussion
  above helps beginners  to appreciate  a  little  more  about
  addressing and how it's defined.


  2.3.  Getting Your Address

  As  a beginner, you'll probably want to know how you can get
  hold of your IP address so that you can start  experimenting
  with TCP/IP on the AMPRNET.

  Address  coordination  in  the  UK has recently changed to a
  more regional  approach with one person in each of the 21 UK
  addressing  regions  taking  responsibility  for  allocating
  addresses locally.    Once  a  month,  each  of  these local
  coordinators sends an update of  newly  allocated  addresses
  to  the  UK  AMPRNET  Address  Coordinator  who is currently
  Chris, G6PWY who can be found at GB7PWY.  Every  few  months
  the whole of the UK's IP addresses are published in a number
  of bulletins  sent  to  TCPIP@GBR.    The  format  of  these
  bulletins are such that they can be used directly  as  input
  to a program than can build the file of TCP/IP stations used
  by the NOS software.

  If  you  are  a  beginner  and  don't know who your local IP
  coordinator is, you can either send mail to Chris as  above,
  who  will tell you who to contact locally, or you can see if
  your local  mailbox  has  any  TCP/IP  information.     Most
  mailboxes  have  a  files  area  dedicated to TCP/IP and you
  maybe able to find your local coordinator's name and address
  there.

  Once you've found your local coordinator, you need to supply
  him/her with the following details :-

       Your Callsign (eg G6DHU)
       Your Christian and Surnames (eg Mike Chace)
       Your IARU QTH Locator (eg IO81tj)
       Your Nearest Postal Town (or full address) (eg Bath)
       Your Local Mailbox (eg GB7IMB)

  Within a few days (or less) you will be allocated your  very
  own address.    Please note that if you are desperate to get
  onto TCP/IP and know locals already on  the  mode,  you  can
  always  agree  a  temporary  address to tide you over before
  your 'official' one is allocated.

  Well, that's the process.  Here is the list of UK IP Address
  coordinators together with the coverage  of  each  of  their
  areas.

             IP REGIONAL CO-ORDINATORS AUGUST 1991

  REGION   CALLSIGN   NAME    @BBS         REGIONAL AREA

    1      G4TUP      DAVE    GB7BPL      Lancashire,Cheshire,Merseyside,
                                          Cumbria,Greater Manchester,I.O.M.
    2      G0BSX      PETER   GB7BSX      Humberside North of the river Humber,
                                          N. S. W. Yorkshire.
    3      G1FNQ      TERRY   GB7SAM      Hereford & Worcester,
                                          Salop,Staffordshire
                                          Warwickshire,West Midlands.
    4      G4KLX    JONATHAN  GB7HMZ      Humberside South of the river Humber,
                                          Derbyshire,Leicestershire,
                                          Lincolnshire Nottinghamshire.
    5      G3NRW      IAN     GB7BIL      Bedfordshire,Cambridgeshire,
                                          Northamptonshire.
    6      G1PLT      PAUL    GB3XP       Berkshire,Buckinghamshire,
                                          Oxfordshire
    7      G8GGI      BOB     GB3XP       Greater London south of the river
                                          Thames,Surrey.
    8      G8ZHR      NICK    GB3XP       Kent,East & West Sussex.
    9      G3KFN      ALAN    GB7PLY      Cornwall & Devon.
   10      VACANT                         Dyfed,Gwent,Mid Glamorgan,Powys,
                                          S & W Glamorgan.
   11      GW4HDR     ALAN    GB7OAR      Clwyd,Gwynedd.
   12      GM4YED     ROBIN   GB7EDN      Grampian,Highlands,Orkneys,Shetlands,
                                          Tayside,Western Isles.
   13      GM4YED     ROBIN   GB7EDN      Borders,Fife,Lothian.
   14      GM4SGB     SUSAN   GB7SAN      Central,Dumfries & Galloway,
                                          Strathclyde
   15      GI0PEZ     DAVE    GB7TED      Northern Ireland.
   16      G8KBB      DAVE    GB7MXM      Essex,Norfolk,Suffolk.
   17      G4WPT      DAVE    GB7BNM      Dorset,Hampshire,Wiltshire.
   18      G6AUC      HARRY   GB7NCL      Cleveland,Durham,Northumberland,
                                          Tyne & Wear.
   19      G8FSL      ANDREW  GB7HSN      Greater London north of the river
                                          Thames,Hertfordshire.
   20      G6DHU      MIKE    GB7IMB      Avon,Gloucestershire,Somerset.
   21      VACANT                         Isle of Wight,Channel Islands.


  3.  Software News

  Well,  not  much  to  report  since  the last newsletter I'm
  afraid!

  PA0GRI is currently taking a well  earned  holiday  and  has
  left his  last    release  at v1.7h.  I don't think there is
  anything exciting in that release just a few tweaks  to  the
  code here and there.

  WNOS from DB3FL is expected to be released at v2c soon.

  Mike  Dent (G6PHF @ GB7ULV) and Neil Mercer G3UVQ have added
  some useful  code to the G1EMM/PA0GRI baseline to allow SMTP
  headers to be stripped from  mail  that  is  gatewayed  from
  TCP/IP stations to AX.25 BBSes or PMSes. Also included are a
  few  commands to add a BBS NIC and some other information to
  bulletins mailed from a TCP/IP station.  Please contact Mike
  for details.

  Those  of  you  (any  ?)  running  a  Unix  machine  may  be
  interested  to know about some German software called WAMPES
  (Wuertemberg Amateur MultiProtocol  Experimental  Software).
  This runs under HP/UX and 386-IX Unix and supports :-

       TCP, IP, UDP, Telnet, FTP, SMTP, finger etc
       AX.25 with autorouting and hop2hop acknowledgment
       TCP convers (chat) node on port 3600
       NET/ROM (L3 and L4 only)
       Full user access to unix shell for mail, news etc

  Perhaps  the  most  interesting  of  the features is the TCP
  based convers node - a novel idea.

  A number of German nodes (eg DB0ID) are using this  software
  and it  seems  to  work well.  This is the sort of thing I'd
  like to see in the UK but we'll need a far better RF network
  first!

  I'm still in the process of finding out about this  software
  (despite  not  having the dosh for a 386, let alone Unix box
  :-). If you would  like  info,  drop  me  a  line  and  I'll
  translate  the  German  text  and  pass  it along but please
  *don't* ask me for the software - I haven't got it!



  4.  Network News

  Just a small section - this time from Chris  G6PWY  -  about
  his local IP network.  In his own words....

  A  few  months  ago you asked for info on TCP/IP activity in
  our local area, there are a number of local 24  hr  stations
  in  region  1,  namely  GB7PWY, GB7TCP, G0GSR, G6CRV, G6PHF,
  G4TUP, the only stations to  take true 3rd  party  mail  are
  GB7PWY  and  GB7TCP,  both  stations  take mail onto the NTS
  network, GB7PWY operates on 144.625 (TCP/IP),  432.675  (FBB
  bbs  with  bpq  node linked to 144.625 on a serial cable) on
  both ports I can take  mail  addressed  to  any  where  both
  national and international, with replies either on TCP/IP or
  NTS. I'm not sure on the setup for GB7TCP.

  One of the other stations G0GSR is located at a good site on
  top  of  Winter Hill, near Bolton, he can take smtp mail for
  almost all of region 1, if he can't  get  it  there  direct,
  there are other routes to use.

  Thanks  Chris.  If  you  would like to let others know about
  what your local  network is doing, please drop me a line  at
  any of the addresses at the end of the newsletter.


  5.  Tutorial - Datagrams and Virtual Circuits

  A number of users seem to be confused as to what these terms
  actually mean  and  what  they are.  I'll attempt to explain
  here!

  Let's think about AX.25 as we are all used to it.   In  case
  you hadn't realised, there are actually two distinct ways to
  send packets containing information  using AX.25 at Level 2.
  (Note: I use the terms 'frame' and 'packet'  interchangeabl here)

  The  first  way  is to connect (eg CONNECT G9ZZZ) tod    forth
  (using  I  (Information) frames) and these get acknowledged,
  ensuring that they got to the other end intact.

  The second method is a little less obvious.  Think about all
  those packets you see addressed to BEACON (yechhh!), and ID.
  They aren't addressed to any one station but  they  do  send
  information.  As you probably have also seen, these kinds of
  packets   get   sent   with   a   type   of  UI  (Unnumbered
  Information).

  It should now be pretty obvious that the first  method  sets
  up   a  circuit  between  the  two  stations  *before*  data
  (information) is  sent.    This  is  the  so-called  Virtual
  Circuit. The second method is really a Broadcast and as such
  it  conveys  information  *without*  setting  up a 'circuit'
  first.

  How does this relate to TCP/IP ?  Well, since TCP/IP can use
  AX.25 at Level 2 (the link-layer) to send  it's  information
  it is able to exploit both these methods to send information
  except  this  time the information is of course TCP/IP data.
  The  NOS/NET  'mode'  command  sets  whether  we  will   use
  datagrams (UI broadcasts) or virtual circuits to send TCP/IP
  data.  That is...

        net> mode 144 datagram # We'll use 'broadcast' mode
        or
        net> mode 144 vc # We'll use virtual circuit mode

  Enough waffle  -  lets  take  a real example.  G6DHU-5 is in
  direct range with G4WRW-5. We  both  set  datagram  mode  as
  above and  then  start  a  telnet session.  The software now
  just 'wraps up' TCP/IP frames  addresses them to  the  other
  station and  sends  them  out  as  broadcasts.    So someone
  watching with 'trace' would see something like

             G6DHU-5 -> G4WRW-5  UI  PID=IP
             data......data

  When we finish, there's  nothing  to  do  except  close  the
  TCP/IP connection and just stop sending the broadcasts.

  In the other case, we would set mode to vc and the following
  would  happen;  transparently,  my  software  would  send  a
  connect to G4WRW-5, wait for the ack and then start  sending
  data back and forth, so someone watching might see :-

             G6DHU-5 -> G4WRW-5 I S5 R7 PID=IP
             data....data
             G4WRW-5 -> G6DHU-5 RR NR=6 (the acknowledgement)

  When  we  finish,  again the TCP/IP connection is closed but
  then (again transparently) the software disconnects at Level
  2 by sending a disconnect packet to the other station.

  What use is all this then ?  Well,  you  may  have  realised
  that  in  the  case  where broadcasts are used, there are no
  acknowledgements (at the AX.25  level).    This  means  that
  using   datagram  mode  has  the  advantage  of  being  more
  effecient and faster  over  *reliable*  paths  (i.e  when  a
  broadcast isn't  often lost).  Virtual circuits are a better
  bet when the path is poor and we need the  security  of  the
  AX.25  acknowledgements  to tell us that the TCP/IP info got
  to the other end OK but the disadvantage  is  that  we  must
  always  wait for AX.25 to do it's job for us and if the path
  is particularly poor the retries may mean a slower (but more
  reliable!) link.

  Remember that just because I've shown  a  direct  connection
  between  two  stations, doesn't mean that you are restricted
  to this in either datagram or VC mode!  You can use  ARP  to
  set a digipeater path between stations if necessary.


  6.  221. Closing

  As  usual,  my  'TCP/IP  Beginner's  Information Package' is
  available, if you send me a disk (MSDOS  1.44M/720k  3.5inch
  or  Atari ST) a return address label and the return postage.
  Back Issues of this newsletter can also be included  on  the
  same disk if you wish.

  Please  send suggestions and articles for inclusion to me at
  the following  addresses ;

       84 Frankland Close
       Bath
       Avon
       BA1 4EL

  or via e-mail ([e-mail]),  AMPRNET  g6dhu.ampr.org
  [44.131.20.3] or AX.25 NTS BBS (G6DHU@GB7IMB).

  I  can accept material on 1.44M/720k IBM/MS-DOS and Atari ST
  3.5 inch format  disks and if  you  want  them  back  PLEASE
  include the return postage.

  All material greatfully received!

  73 until next time, Mike.

                       [End Of Newsletter]