bill@twg.bc.ca (Bill Irwin) (10/30/90)
We are currently using a couple of the low end MultiTech (MT) 9600 bps modems, which can only talk to their own kind at 9600, and want to step up our connection speed (especially with our news feed site). MT have a 9600 V.32 model which I believe will talk to any V.32 modem. My question is simply, will this modem talk to the Trailblazers that seem to be so popular with uucp sites at 9600, or does the TB use a proprietary method of establishing the 9600 connection? I don't really want to open up a religious war on modem popularity (I know the TBs are very popular), but I would like to know if there are any tangible advantages to going with a TB V.32 over the MT. We have sold many MTs and used them for years, are familiar with their codes, like their reliability, and would like to stay with them, unless there are good reasons to switch. I have heard that the TBs are designed to work better in a uucp environment. What, exactly, does this mean? I appreciate any non-drum beating, non-emotional, _objective_ advantages of the TB over the MT, to assist in the decision process. Thanks. -- Bill Irwin - The Westrheim Group - Vancouver, BC, Canada ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ uunet!van-bc!twg!bill (604) 431-9600 (voice) | UNIX Systems bill@twg.bc.ca (604) 430-4329 (fax) | Integration
cpcahil@virtech.uucp (Conor P. Cahill) (10/30/90)
In article <298@twg.bc.ca> bill@twg.bc.ca (Bill Irwin) writes: >is simply, will this modem talk to the Trailblazers that seem to be so >popular with uucp sites at 9600, or does the TB use a proprietary method >of establishing the 9600 connection? The reason TBs are uses so extensively in the UNIX market is that they have thier own PEP protocol (14xxx bps half duplex) and they spoof the uucp protocol. This results in very fast uucp transfers. PEP is not compatible with V.32. The drawback to PEP is that it is unsatisfactory for interactive sessions. We have a couple of T2500s (along with six Microcom V.32 modems) and use them in PEP mode for uucp sessions and V.32 mode for interactive sessions. Another good point for PEP is that the protocol is much more resistant to line problems than V.32. On some of our interactive connections, the V.32 protocol give up quite frequently and I usually end up falling back to PEP, which has been 100% reliable over the same connection, even though the chopiness of PEP bothers us. -- Conor P. Cahill (703)430-9247 Virtual Technologies, Inc., uunet!virtech!cpcahil 46030 Manekin Plaza, Suite 160 Sterling, VA 22170
mju@mudos.ann-arbor.mi.us (Marc Unangst) (10/31/90)
bill@twg.bc.ca (Bill Irwin) writes: > 9600 V.32 model which I believe will talk to any V.32 modem. My question > is simply, will this modem talk to the Trailblazers that seem to be so > popular with uucp sites at 9600, or does the TB use a proprietary method > of establishing the 9600 connection? Any V.32 modem will connect to a Telebit that supports V.32, in V.32 mode. However, Telebits also support the proprietary PEP protocol, which they only talk with each other. PEP is a half-duplex protocol that can reach REAL-WORLD throughputs of around 18,000bps. Unfortunately, not all the Telebit modems support V.32. Only the T2500 and T1500 support it; the T1000 and Trailblazer Plus only support PEP at 9600, and your Multitech modem won't be able to talk to them. If your UUCP neighbors have T2500s, then your MT modem will be okay; if your UUCP neighbors only have Trailblazer Pluses, then your MT modem will be worthless for 9600bps connections. > I have heard that the TBs are designed to work better in a uucp > environment. What, exactly, does this mean? That means that they impliment the UUCP 'g' protocol in hardware and spoof the UUCP processes at each end by talking 'g' to the computer, but talking PEP between themselves. This increases throughput dramatically. 'g' over V.32 seems to max out at around 800cps. 'g' between two Telebits in UUCP spoofing mode can go as high as 1500cps or so. Trailblazers also, incidentally, have similar spoofing capabilities for Xmodem, Ymodem, and Kermit. > I appreciate any non-drum beating, non-emotional, _objective_ advantages > of the TB over the MT, to assist in the decision process. Thanks. I'd definitely go with the T2500. They're going for around $900 now (probably less with volume discounts), and do much more than a plain V.32 modem will. Just about the only drawback of the T2500 is that the maximum supported interface speed is 19.2Kbps; this limits somewhat the maximum throughput possible with V.42bis compression. -- Marc Unangst | mju@mudos.ann-arbor.mi.us | "Bus error: passengers dumped" ...!umich!leebai!mudos!mju |
mikes@iuvax.cs.indiana.edu (Michael Squires) (10/31/90)
In article <RRkVR1w163w@mudos.ann-arbor.mi.us> mju@mudos.ann-arbor.mi.us (Marc Unangst) writes: > >Unfortunately, not all the Telebit modems support V.32. Only the >T2500 and T1500 support it; the T1000 and Trailblazer Plus only >support PEP at 9600, and your Multitech modem won't be able to talk to The TB+ runs PEP at 19.2K also, of course. I've not seen V.32 uucp throughput higher than 650 bytes/sec on my system and frequently see PEP throughput in the 1500 - 1700 byte/sec range. The V.32 modem is a USR DS (no V.42, yet); PEP modem is a TB+. -- Mike Squires (mikes@iuvax.cs.indiana.edu) 812 855 3974 (w) 812 333 6564 (h) mikes@iuvax.cs.indiana.edu 546 N Park Ridge Rd., Bloomington, IN 47408 Under construction: mikes@sir-alan@cica.indiana.edu
bob@MorningStar.Com (Bob Sutterfield) (10/31/90)
In article <RRkVR1w163w@mudos.ann-arbor.mi.us> mju@mudos.ann-arbor.mi.us (Marc Unangst) writes:
...the T1000 and Trailblazer Plus only support PEP at 9600,
Put more precisely, the only 9600 or faster modulation scheme
supported on the T1000 and Plus is PEP.
The Plus serial interface can clock at up to 19200.
...and your Multitech modem won't be able to talk to them.
Should work fine at 2400 + MNP5 (if the MT has it) which should yield
around 4500bps throughput, but not at 9600 or better.grr@cbmvax.commodore.com (George Robbins) (11/01/90)
In article <68950@iuvax.cs.indiana.edu> mikes@iuvax.cs.indiana.edu (Michael Squires) writes: > In article <RRkVR1w163w@mudos.ann-arbor.mi.us> mju@mudos.ann-arbor.mi.us (Marc Unangst) writes: > > > >Unfortunately, not all the Telebit modems support V.32. Only the > >T2500 and T1500 support it; the T1000 and Trailblazer Plus only > >support PEP at 9600, and your Multitech modem won't be able to talk to > > The TB+ runs PEP at 19.2K also, of course. Both the T1000 and the TB+ support a 19.2KBPS interface rate, with the TB+ being internally crippled to only support throuput at a 9600BPS rate. With a 19.2 KBPS interface rate TB+ performance is gererally much faster than 9600 KBPS, while there may be some measurable performance increase if both T1000's are running at 19,200 KBPS rather than 9,600... It's worth a try if you're using T1000's mostly for non-interactive use. -- George Robbins - now working for, uucp: {uunet|pyramid|rutgers}!cbmvax!grr but no way officially representing: domain: grr@cbmvax.commodore.com Commodore, Engineering Department phone: 215-431-9349 (only by moonlite)
bill@twg.bc.ca (Bill Irwin) (11/01/90)
mju@mudos.ann-arbor.mi.us (Marc Unangst) writes: >Unfortunately, not all the Telebit modems support V.32. Only the >T2500 and T1500 support it; the T1000 and Trailblazer Plus only >support PEP at 9600, and your Multitech modem won't be able to talk to >them. If your UUCP neighbors have T2500s, then your MT modem will be >okay; if your UUCP neighbors only have Trailblazer Pluses, then your >MT modem will be worthless for 9600bps connections. I've heard that if a site has a T2500 (which supports both PEP and V.32) set in PEP mode, and an incoming call tries to establish a V.32 connection, the T2500 *will not* switch to V.32 mode. In other words, it is locked in PEP mode. If this is true, it means that a Multitech V.32 (or any other V.32) calling a site for usual uucp transfers, will be forced to connect at 2400 because the T2500 will not talk V.32, unless it is set in that mode prior to the incoming call. That would make buying a non Telebit modem that supports V.32 a waste if you are intending to use it for uucp connections, among other things. True? -- Bill Irwin - The Westrheim Group - Vancouver, BC, Canada ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ uunet!van-bc!twg!bill (604) 431-9600 (voice) | UNIX Systems bill@twg.bc.ca (604) 430-4329 (fax) | Integration
bob@MorningStar.Com (Bob Sutterfield) (11/02/90)
In article <300@twg.bc.ca> bill@twg.bc.ca (Bill Irwin) writes:
I've heard that if a site has a T2500 (which supports both PEP and
V.32) set in PEP mode, and an incoming call tries to establish a
V.32 connection, the T2500 *will not* switch to V.32 mode.
Well-behaved T2500s generally have S50=0, to allow any sort of modem
to connect. The behavior you describe would be S50=255 (PEP only),
which indicates that the T2500's owner doesn't want to talk to
anything but another Trailblazer, in which case why did they bother
buying the 2500's V.32 capability?mju@mudos.ann-arbor.mi.us (Marc Unangst) (11/03/90)
bill@twg.bc.ca (Bill Irwin) writes: > I've heard that if a site has a T2500 (which supports both PEP and V.32) > set in PEP mode, and an incoming call tries to establish a V.32 > connection, the T2500 *will not* switch to V.32 mode. In other words, it > is locked in PEP mode. If this is true, it means that a Multitech V.32 > (or any other V.32) calling a site for usual uucp transfers, will be > forced to connect at 2400 because the T2500 will not talk V.32, unless it > is set in that mode prior to the incoming call. Um, it is possible to set up a Telebit modem so it only gives PEP tones, and doesn't offer V.32, or V.22bis, or anything else, so only other Telebits can connect. However, it's also possible to tell it to autobaud; I have mine set up to go V.32->V.22bis->Bell 212A->Bell 103->PEP, since there aren't a lot of PEP modems calling here (this is mainly a BBS machine). The modem defaults to PEP->V.32->V.22bis->Bell 212A->Bell 103. -- Marc Unangst | mju@mudos.ann-arbor.mi.us | "Bus error: passengers dumped" ...!umich!leebai!mudos!mju |
dhesi%cirrusl@oliveb.ATC.olivetti.com (Rahul Dhesi) (11/07/90)
A pragmatic factor to consider is that Trailblazers are heavily discounted, while MultiTechs are marketed only through a limited number of authorized distributors with little discounting. So look at the prices carefully. -- Rahul Dhesi <dhesi%cirrusl@oliveb.ATC.olivetti.com> UUCP: oliveb!cirrusl!dhesi
rick@uunet.UU.NET (Rick Adams) (11/08/90)
One real advantage of the telebit v.32 over others is that the T1500 supports dialup passwords and callback security in the modem. It also has some other useful register settings that are not provided in other brands. --rick
bourman@hpcc01.HP.COM (Bob Bourman) (11/09/90)
The Multitch also has dialback & remote config. You can get the V.42 MT932EC for around $695.00f you talk to a distributor.
wolfgang@wsrcc.com (Wolfgang S. Rupprecht) (11/09/90)
>One real advantage of the telebit v.32 over others is that the T1500 >supports dialup passwords and callback security in the modem. I don't understand how one can do a functional callback security in a modem. One known attack method is to dial up the modem, log the request for a callback and quickly drop the line. Now call back before the call-back modem has a chance to dial out. The modem will think it is dialing the call-back number, but it is really already talking to the attacker (who may even by sending a dialtone down the line, and recording the callback number that the remote modem is toning down the line.) The fix for this attack is to *never* call out with a callback on a line that can be called from the outside. This precludes use of the so called "callback security" features resident in modems. Manufacturers that sell modems with this feature aren't really doing folks a big favor. -wolfgang -- Wolfgang Rupprecht wolfgang@wsrcc.com (or) uunet!wsrcc!wolfgang Snail Mail Address: Box 6524, Alexandria, VA 22306-0524
rick@uunet.UU.NET (Rick Adams) (11/09/90)
The telebit modems require a password before they will call back. THis makes it fairly difficult to spoof. Also, remember that its a FEATURE that the callback is in the modem. THat way if your host doesnt support callback, you can get a reasonable approximation.
howardl@wb3ffv.ampr.org ( WB3FFV) (11/10/90)
From article <111109@uunet.UU.NET>, by rick@uunet.UU.NET (Rick Adams): > One real advantage of the telebit v.32 over others is that the T1500 > supports dialup passwords and callback security in the modem. > > --rick Hello, Unless I misunderstand your statement, the Multitech modem also does the same thing. It will allow you assign a dialup password, and when entered correctly it will perform a callback. One other neat thing, I hear that Multitech has released a V.32 modem that does V.42bis at 38,400bps and also does 9600bps FAX (all in the same modem)... ------------------------------------------------------------------------------- Internet : howardl@wb3ffv.ampr.org | Howard D. Leadmon UUCP : wb3ffv!howardl | Advanced Business Solutions TELEX : 152252474 | 210 E. Lombard St - Suite 410 Telephone : (301)-576-8635 | Baltimore, MD 21202
lail@baudr8.enet.dec.com (Robert G Lail) (11/10/90)
In article <1990Nov8.193019.4064@wsrcc.com>, wolfgang@wsrcc.com (Wolfgang S. Rupprecht) writes: |> From: wolfgang@wsrcc.com (Wolfgang S. Rupprecht) |> Newsgroups: comp.dcom.modems |> Subject: Re: Any REAL advantage of Trailblazer V.32 over MultiTech V.32? |> |> >One real advantage of the telebit v.32 over others is that the T1500 |> >supports dialup passwords and callback security in the modem. |> |> I don't understand how one can do a functional callback security in a |> modem. One known attack method is to dial up the modem, log the |> request for a callback and quickly drop the line. Now call back |> before the call-back modem has a chance to dial out. The modem will |> think it is dialing the call-back number, but it is really already |> talking to the attacker (who may even by sending a dialtone down the |> line, and recording the callback number that the remote modem is |> toning down the line.) Having been the architect of callback security in the Digital Equipment Corp modems I have a good idea of the problems encountered using the same telephone line for callback that is used for dial-in access. The attack method you mention has two problems. One is that any good callback security modem will not execute a callback until it has authenticated the initial caller. In Digital's callback security this is done by requesting a password (6 to 10 characters long) that is assigned to a fixed phone number, both of which are stored in non-volatile memory in the modem. Once the password has been authenticated the callack modem hangs up the connection and initiates the callback. Assuming the user that was authenticated is not at the telephone number associated with the password used, and wants to fool the modem, hanging up and calling right back would not work because the modem will detect the loss of carrier. In the Digital modems once a user has been authenticated and the connection is broken the modem will not answer incoming calls again until a callback is completed successfully or the modem fails to make a connection to the assigned telephone number after two attempts. Also the Digital modems monitor phone line current as well as carrier. They will not initiate a callback unless both carrier and line current drop for a specific time. One older method of spoofing callback modems was to use a hack in the telephone system that allowed the originating party to hold the line open if the remote party hung up. The remote user would not hangup when the callback modem did and then would spoof the dial-tone and call progess signals when the callback modem attempted its callback. Newer CO and PBX equipment will not allow this method because they dump the connection if either party hangs up for more than a specific time. In the Digital modem the period between hang-up and callback attempt is programable with a minimum of 10 seconds and a maximum of 60 seconds. |> |> The fix for this attack is to *never* call out with a callback on a |> line that can be called from the outside. This precludes use of the |> so called "callback security" features resident in modems. |> I agree that when absolute maximum security is needed a callback security function should accept incoming calls on one phone line and place the callback on a second line. The telephone service should be set up such that the dial-in line is incoming only, no dial-out access, and the dial-out line is out-going only, |> Manufacturers that sell modems with this feature aren't really doing |> folks a big favor. I believe callback security, even single line, is a valuable feature to help manage network security. Properly configured callback security modems on properly configured telephone lines can effectively shield your systems from most attacks. -Bob Lail
jeff@xanadu.com (Jeff Crilly N6ZFX) (11/14/90)
In article <300@twg.bc.ca> bill@twg.bc.ca (Bill Irwin) writes: > >I've heard that if a site has a T2500 (which supports both PEP and V.32) >set in PEP mode, and an incoming call tries to establish a V.32 >connection, the T2500 *will not* switch to V.32 mode. In other words, it >is locked in PEP mode. If this is true, it means that a Multitech V.32 >(or any other V.32) calling a site for usual uucp transfers, will be >forced to connect at 2400 because the T2500 will not talk V.32, unless it >is set in that mode prior to the incoming call. > >That would make buying a non Telebit modem that supports V.32 a waste if >you are intending to use it for uucp connections, among other things. > >True? Nope. As another poster pointed out, there is a register that controls this, and when properly set, the T2500 can answer PEP or V.32 calls. We have a dialup V.32 that is used for incoming calls where the remote modems are USR Duals or other Telebits (T2500s and Trailblazer Plus), and it all works fine: V.32 connections for the modems with V.32 and PEP connections for the Trailblazers. As for the T2500s, it is up to the originating user (software) to decide whether to use PEP or V.32. For interactive stuff we use V.32 on those modems. Also, I believe that your uucp neighbor, uunet, uses T2500s nowadays, for V.32 and PEP connections. >-- >Bill Irwin - The Westrheim Group - Vancouver, BC, Canada >~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >uunet!van-bc!twg!bill (604) 431-9600 (voice) | UNIX Systems >bill@twg.bc.ca (604) 430-4329 (fax) | Integration Jeff Crilly (N6ZFX) AMIX Corporation 2345 Yale Street Palo Alto, CA 94306 jeff@amix.com, {uunet,sun}!markets!jeff, N6ZFX@N6IIU.#NOCAL.CA.USA