[comp.protocols.tcp-ip] SLIP discussion at the Interoperability Conference

rdhobby@ucdavis.edu (Russ Hobby) (12/11/87)

Here  is what  happened at  the TCP/IP  Interoperability Conference with 
regards to SLIP. 

The  BOF session was too large to  get any protocol standards work done, 
but  the group provided input as to what  needs to be covered by the the 
standard  and some  of the  potential uses  for SLIP connections.  There 
seemed  to be two types of usage for the new standard SLIP protocol. One 
is  the connection of  isolated computers that  do not have  access to a 
LAN.  PCs would be a  big proportion of the  computers in this category, 
but certainly any type of computer can use the capability. 

The  other use of SLIP  connections is for temporary  network links. The 
idea  is to advertise a  route to another location  all the time, but to 
dialup  and establish the connection to that location only when there is 
traffic.  The first packet will be delayed while the connection is being 
made,  but  there  after  traffic  would  flow smoothly. After a certain 
period  of no traffic  the connection would  be dropped, thus  saving on 
communications costs. 

The  evening after the BOF  session, a smaller group  of us got together 
and  got some productive  work done towards  the writing of an RFC for a 
SLIP  type protocol.  Here is an overview of what  was decided (at least 
what I can decipher from my notes). 

       1) The RFC will cover both connection and line protocols 

       2) Connection specifications will cover negotiation of items such 
       as  network  addresses,  authentication,  line speed, compression 
       used, and probably other items. 

       3)  The line  protocol will  contain one  byte in  the header  to 
       indicate  the protocol in the packet. This allows the use of line 
       control  packets  for  maintaining  the  serial  link, as well as 
       allowing  other protocols in addition to  IP and the line control 
       to use the connection. 

Much  more detail was  discussed, but I  don't want to  bore you with it 
now.   It  was  thought  that  an  RFC   draft  could  be  done  and  an  
implementation to test it in a couple of months. 

UC  Davis will be implementing the new standard by modifying our current 
work.  So some of you  may want to wait  for the standard version rather 
than using what we have available now. But then if you have an immediate 
need,  out old version will be there. Since the standard version will be 
more  than  experimental  software,  it  will  more  complete and better 
documented. 
                                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

mminnich@UDEL.EDU (Mike Minnich) (12/12/87)

Isn't there a problem with dynamically changing the kernel's routing table
(via a slattach/sldetach mechanism) while user level routing agents 
such as egpup, routed, or gated are running?  

This has typically not been a problem for hardwired SLIP connections,
since the slip interfaces can be configured before routing agents start up,
and are left alone thereafter.

One solution would be to home all dial-in connections on another host
that would presumably use static routing, but that requires the
"host" to function as a "gateway", which is something I would like to 
minimize.

mike