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From: hedrick@TOPAZ.RUTGERS.EDU.UUCP
Newsgroups: comp.protocols.tcp-ip
Subject: Re: T1 and distant IP networks
Message-ID: <8709170359.AA04435@topaz.rutgers.edu>
Date: Wed, 16-Sep-87 23:59:47 EDT
Article-I.D.: topaz.8709170359.AA04435
Posted: Wed Sep 16 23:59:47 1987
Date-Received: Sat, 19-Sep-87 08:38:22 EDT
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We have three situations similar to what you describe, i.e. pairs of
IP networks connected by T1.  We are using the following three
approaches:
  - VAXes running Ultrix with the T1 line connected to DMR11's.
	Avanti T1 Mux's are used to cut down the speed, since
	no known DEC line controller can deal with speeds this
	high.  This is probably the cheapest of the 3 methods,
	if you already have the VAXes, but also give the worst
	performance and has other disadvantages.
  - Cisco IP routers, using either Digilink T1-izers (boxes that
	take a vanilla 1.5Mb synchronous signal and format it
	for T1) or Avanti T1 muxes (for cases where we need
	to use the line for things other than the IP link, e.g.
	talking to 3270 cluster controllers at the other site).
	This is my preferred solution.  (Of course vendors other
	than Cisco also make routers that would do this.  You
	might want to talk to Proteon and U-B also.)
  - U-B bridges.  These would also need either a T1-izer or
	T1 mux.  These are level 2 bridges rather than level 3
	routers, which have both advantages and disadvantages.
	(They have been discussed so often that I am not about
	to repeat the discussion.)  The U-B bridges have worked
	very well, but note that you must dedicate an IBM PC
	or clone to boot them.  (I believe the same PC can be
	shared for booting all U-B products.)  I strongly oppose
	the use of this approach if the two IP networks are
	under different administration, and if you don't have
	support staff available at both ends.  Junk coming from
	the other end can sink your network.