[3827] in linux-net channel archive
Re: CSU/DSU's, async RS-232, and PPP. How?
daemon@ATHENA.MIT.EDU (Michael H. Warfield)
Wed Jul 24 05:51:56 1996
To: fbyte@sub-zero.mit.edu (Kevin D. McCormick)
Date: Tue, 23 Jul 1996 09:53:01 -0400 (EDT)
From: "Michael H. Warfield" <mhw@wittsend.com>
Cc: linux-net@vger.rutgers.edu
In-Reply-To: <Pine.LNX.3.91.960722023701.978A-100000@sub-zero.mit.edu> from "Kevin D. McCormick" at Jul 22, 96 02:56:33 am
You're E-Mail address is at MIT so I'll "assume" that you are in
the US and tailor my comments for a US audience...
Kevin D. McCormick enscribed thusly:
> I've looked through the HOWTOs and FAQs, yet I can't find a confirmation
> that what I want to do here actually works. Can someone let me know if
> I'm on the right track?
> I am setting up a number of dedicated 56k lines. One of the major
> constraints on this project is per-line cost, so we have chosen to use
> CSU/DSU's with an asynchronous interface that will hang off a standard
> (well, 16550A) serial port on a 486DX/4-120 running Linux. Synchronous
> interfaces (especially v.35 interfaces) cost more than we want to spend.
> Maybe.
:
: - Technical questions deleted...
:
> By the way, the CSU/DSU's we picked are made by Bat Electronics, model
> 5696, if I remember, for something like $398. Does anyone have any
> good/bad comments about these boxes (or maybe suggestions for something
> cheaper...) ?
Hmmm... Are you out of reach of ISDN? My BRI's are costing me
only slightly more than the cost of two telephone lines (BellSouth, GA -
your milage may vary), provide me with more than twice the capacity & features
of two POTS (Plain Old Telephone) lines and give me 128K (actually 115K on
ASYNC). That better than twice what you are getting on those dedicated
56K lines and I can't see those lines as being cheap. Last time I did anything
with CSU/DSU DDS lines the price was outragious!
Motorola Bitsurfer PRO's can be had for $349. They support MLPPP and
will give you everthing from a BRI that it has to give. It's little brother,
the Bitsurfer, can be had for $269 and even cheaper for the internal Bitsurfer.
My personal preference is the PRO since I can also drive a POTS device off
the back and support automagical fallback from 128K to 64K while the POTS
port is in use. I use that for my FAX line (which is rarely in use) while
giving me plenty of bandwidth to my dedicated Internet connection.
I have 4 of these lovelies and home and they are great. Only problems
I'm currently dealing with have to do with disabling call waiting on my
POTS ports on the Bitsurfer PROS and a problem with MLPPP between the
PROS and a Livingston PortMaster at my ISP. I'm waiting to have the phone
company remove the call waiting (political nonsense over prepackaged deals)
and both Livingston and Motorola are working to fix the MLPPP problem (RSN
I'm afraid).
To sumarize: Unless things have changed RADICALLY - dedicated 56K
lines are out of date and way WAY more expensive per line than BRI's (Basic
Rate ISDN). ISDN provides over twice the capacity of the dedicated 56K lines.
ASYNC interfaces for BRI's are already much cheaper than your CSU/DSU's.
You say a major constraint is cost. Questions???
> -------------------------------------------------------------------------------
> Kevin "Frostbyte" McCormick kmccorm@mit.edu - root@sub-zero.mit.edu
> Massachusetts Institute of Technology You should be running Linux!
> Q: How many Microsoft engineers does it take to screw in a light bulb?
> A: None. They just define darkness as an industry standard.
Mike
--
Michael H. Warfield | (770) 985-6132 | mhw@WittsEnd.com
(The Mad Wizard) | (770) 925-8248 | http://www.wittsend.com/mhw/
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