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From: ccruss@ucdavis.UUCP (Russ Hobby)
Newsgroups: comp.protocols.tcp-ip,comp.sys.ibm.pc
Subject: Re: PC UNIX wide area networking
Message-ID: <626@ucdavis.UUCP>
Date: Wed, 15-Jul-87 12:36:01 EDT
Article-I.D.: ucdavis.626
Posted: Wed Jul 15 12:36:01 1987
Date-Received: Fri, 17-Jul-87 07:25:18 EDT
References: <272@auvax.UUCP>
Reply-To: ccruss@ucdavis.edu.UUCP (Russ Hobby)
Organization: University of California, Davis
Lines: 39
Xref: mnetor comp.protocols.tcp-ip:579 comp.sys.ibm.pc:5721

SLIP connections seem to be a hot topic this summer so I thought I would 
post  a description of a summer  project we have at UC  Davis. SLIP is a 
cheap  and easy method to  get a computer connected  to a network and is 
particularly  good for microcomputers  since additional hardware  is not 
required. 

SLIP  is lacking in a few areas however. Throughput on slow serial lines 
(1200/2400  baud) can be  quite bad because  of the minimum  packet size 
(all  those  header  fields).  Also  there  is  no  standard  method  of 
establishing a SLIP connection for temporary network hookups. 

Our  project  addresses  the  first  problem  by using an abbreviated IP 
packet  on the SLIP line  and have the SLIP  gateway build legal packets 
before sending them onto the network. Likewise, incoming packets will be 
reduced  before sending them down  the SLIP line. Many  of the fields in 
the  IP packet header are either static  or unnecessary, IF you consider 
the host at the end of the SLIP is a leaf on the network and will not be 
routing.  Static fields are established at  login. Our current plans are 
for  four or eight  byte headers, depending  if the to/from  address has 
changed from the last packet. 

To  solve the second problem, we are creating a standard logon procedure 
that  will make  the connection  and set  the static  fields. We plan to 
support  connections via campus serial connection  (up to 19.2k) as well 
as  via dialup modems (300/1200/2400 baud, although I can not imagine it 
working well at 300!). 

We  doing the development with an IBM PC clone on one end and a VAX with 
4.3bsd  on  the  other.  We  have  started  with  some  of the MIT PC/IP 
derivations  on the PC side,  so that if the  project works out, it will 
usable  by others using the same software.  If there is interest, I will 
post information on how well it works. 

                                Russell Hobby               
                         Data Communications Manager 
     U. C. Davis                 
     Computing Services       BITNET:    RDHOBBY@UCDAVIS 
     Davis Ca 95616           UUCP:      ...!ucbvax!ucdavis!rdhobby 
     (916) 752-0236           INTERNET:  rdhobby@ucdavis.edu