Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!HOGG.CC.UOREGON.EDU!jqj
From: jqj@HOGG.CC.UOREGON.EDU
Newsgroups: comp.protocols.tcp-ip
Subject: dialup SLIP (again)
Message-ID: <8904231332.AA04023@hogg.cc.uoregon.edu>
Date: 23 Apr 89 13:32:27 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 22

It has been suggested (including on this forum) that one could use
dialup SLIP to create backup paths in leased-line wans.  If an
intermediate router in my regional network went down, I could just
automatically call past it and temporarily use a SLIP connection while
the primary was being restored.

Is anybody (besides me) actually experimenting with this use of dialup 
SLIP?  

Has anybody given any thought to how to handle routing in such an
environment?  There seem to be two possible models:
   (1)	The CSnet "dial on demand", in which the SLIP route is
	claimed to exist all the time, but is only active while traffic
	is present.  This has the disadvantage that you can't employ a
	routing protocol like RIP that depends on routinely sending
	reachability data across the link.  CSnet, I gather, uses
	only static routes.
   (2)	Create and advertise a route when needed.  This requires that
	network management software notice that the primary route is
	gone and initiate a connection.  Since network management has
	noticed the loss of connectivity, presumably user applications
	have too.