HDTenEightyP/NetNews huggingface dataset:
From: hyder@mrbean.scd.ucar.edu (Paul Hyder)
Newsgroups: comp.dcom.lans.ethernet
Subject: Re: Early and Late Collision
Date: 31 Jul 92 15:58:39 GMT
Organization: Scientific Computing Divison/NCAR Boulder, CO

>> > On many hosts it is impossible to capture long collisions, only a few
>> > hosts even bother to tell you about them.  You need something like
>> > a LANalyzer to capture the packets.  It is important to know how far
>> > into the packet the collision was, close values point to cable length
>> > and longer ones other problems.
>> 
>> 
>> How can you capture a late collision?  What will you see but the jumble
>> of two simultaneous transmissions?  The bad guy will be the one whose
>> first bit is in trashed by the later bits of the innocent guy.  The
>> easily capturable MAC header will be that of the innocent guy.
>> 
>> 
>> Does the LANalyzer or anything else have enough electronics to try to
>> peel some of the bits apart by assuming the two clocks are different?
>> Or does it compare the signal at several different points on the
>> network, and thereby figure out the bad guy's bits?

<sigh, another broken promise.  ... just figure I lied.>

Slight difference in the meaning of "capture" is the key here.  All
one can easily do is snag a copy of whatever garbled mess was on
the net.  I don't know of any magic to strip it logically back apart.

Late collisions occur far enough into a transmission that you can
often extract the address info and sometimes get clear to the protocol
headers.  As is indicated in the query, you can't tell who or what is
doing the stomping but you can tell who had one of the packets that
will be dropped >AND< how far into the packet the collision occured.
In crisis cases samples taken at various points on the net might give
a set of hosts to start checking.  [Moving around has never worked for
me but then I've also never had the problem end up being a cable that
was too long.]

Most enet chipsets discard bad packets (CRC, late collision, etc) so
you can't actually look at them on a host via utilities like tcpdump.
Custom HW in lan monitors captures most bad packets, sometimes all
you get is jumbled bits that can only loosely be called a packet.
Much of the time there are helpful readable bits at the beginning.

	Paul Hyder
	NCAR
Newsgroups: comp.dcom.lans.ethernet
From: stacy@sobeco.com (Stacy L. Millions)
Subject: Re: Early and Late Collision
Organization: Sobeco Ernst & Young
Date: Fri, 31 Jul 1992 17:04:04 GMT

In hyder@mrbean.scd.ucar.edu (Paul Hyder) writes:
>>> }Once the necessary time for consensus has elapsed and no collision has
>>> }been seen, all nodes should agree that there is a transmission in progress.
>>> }A properly-functioning Ethernet node will not attempt to transmit between
>>> }seeing that somebody else is transmitting and the end of that transmission.
>>> }A late collision is one occurring after consensus should have been achieved.
>>> }It means something is badly wrong somewhere -- either a misconfigured
>>>                                                          ~~~~~~~~~~~~~
>>> }network or a malfunctioning node.
>>> 
>> Most likely a segment longer than the longest allowed.
>
>....   In recent years the ones I've seen have included bad
>transceivers, bad repeaters, too many repeaters, and multiport
>transceivers three deep.

And lets not forget trying to run 10BaseT over non-twisted cable,
split pair cables, or cables with >11.5dB loss. "misconfigured network"
understates the possible problems quite nicely. I'll have to remember
that one :-).

"Ode to 802.3 standards"
by Some Joe With Cable

How do I break thee? Let me count the ways.

:-(

-stacy

-- 
"In Russia we have a saying,                                   stacy@sobeco.com
Women are like trucks... and that's it."                        stacy@sobeco.ca
    - Yakov Schmirnoff                                       uunet!sobeco!stacy
From: IO92142@MAINE.MAINE.EDU (James)
Newsgroups: comp.dcom.lans.ethernet
Subject: Digital Telephony/FBI?
Date: 28 Jul 92 04:31:44 GMT
Organization: University of Maine System

Hi.  I recently read this in a MacWeek magazine.  If anyone is up to
speed on these and related issues, please contact me via email.
Digital Telephony-MacWeek-7.12.92

Washington

The FBI has sharpened language in proposed legislation that would require
government wiretap access to all U.S. voice and data networks.

The proposal, known as Digital Telephony, is a response to new telephone
technology, which the FBI claims makes eavesdropping more difficult.  The new
draft includes and explicit call for law enforcement monitoring facility with
remote access to every voice and data network in the country.  The FBI also
called for the Federal Communications Commission to relinquish its
standards-setting and device-certification authority to the U.S. Attorney
General, who could force wiretap-secure networks open with fines of up to
$10,000 a day.

The FBI told computer and communications industry leaders that its wiretap
shopping list includes access to all present and future network technologies,
including Ethernet, X.25, cellular networks and Electronic Data Interchange
systems.

"In its current form Digital Telephony would open the entire universe to
wiretaps," said Don Gilbert, information services directory at the Washington,
D.C.- based American Petroleum Institute.  He is among 40 industry leaders
opposing the proposal.

The bill still has not found a sponsor on Capitol Hill.  Nevertheless, the FBI
has not backed down.

Attorney Mike Godwin, counsel to the Cambridge, Mass.-based Electronic Frontier
Foundation, said the FBI remained adamant because Digital Telephony is a
backhanded attempt to prevent the use of encryption on U.S. networks.  The
Department of Justice, the FBI's parent agency, launched anti encryption
legislation in 1991, Senate Bill 266, which did not pass.

"They are asking for an outrageous level of access because they can back down on
the condition that a ban be placed on encryption," Godwin said.
"It leaves us where we would have been if S.B. 266 has passed."

=-=-=-=-=-=--=-=-=-=
James Gray                           Bitnet   :  IO92142@Maine
University of Maine                  Internet :  IO92142@Maine.Maine.Edu
Newsgroups: comp.dcom.lans.ethernet
From: brett@cxbne.cx.OZ.AU (Brett Worth)
Subject: Re: 10basT Question
Organization: Comperex Australia Pty Limited
Date: Thu, 23 Jul 1992 08:28:28 GMT

karl@hpscit.sc.hp.com (Karl Watanabe) writes:

>In comp.dcom.lans.ethernet, jonathan@netcom.com (Jonathan Ridder) writes:

>> Though this is not usually done (and may not officially be supported?),
>> you can connect them with a crossover cable.  The crossover cable is
>> wired so that the receive pairs connect to the transmit pairs.  If I
>> recall,  this would be pin 1 to pin 3 and pin 2 to pin6.

>The 10baseT chip transceiver from AMD automatically has polarity reversal.
>Therefore it wouldn't be necessary to use a crossover cable.

Polarity reversal detection will correct if tx+ and tx- or rx+ and rx- are
reversed but not if the transmit pair is connected to the transmit pair
and the receive pair is connected to the receive pair.  You still need the
cable.

>Karl Watanabe
>karl@sc.hp.com

--------------------------------------------------
Brett Worth
Comperex Brisbane Australia - brett@cxbne.cx.oz.au
"I love it here"
--------------------------------------------------
From: mchadwick@galaxy.gov.bc.ca
Newsgroups: comp.dcom.lans.ethernet
Subject: re: Lantastic and PCP/IP
Date: 28 Jul 92 15:17:00 -0700
Organization: BC Systems Corporation

I am running a 200 person lan using ethernet and Lantastic.
We want to bridge the network into the outside world of tCP/IP. Does anyone out
there know of a protocol converter that will enable Lantastic to talk to other
networks via TCP/IP?
Newsgroups: comp.dcom.lans.ethernet
From: rob@ncc06.ct.louisville.edu (Rob Miracle)
Subject: Re: Is Starlan really Ethernet?
Organization: Information Technology, University of Louisville
Date: Mon, 27 Jul 1992 15:45:20 GMT

In article <7520@public.BTR.COM> thad@public.BTR.COM (Thaddeus P. Floryan) writes:
>From: thad@public.BTR.COM (Thaddeus P. Floryan)
>Subject: Re: Is Starlan really Ethernet?
>Date: 26 Jul 92 23:05:33 GMT

>In article <BrwKyM.67t@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes:
>>Starlan is vaguely similar to 10BaseT, but is not in any way compatible
>>with it.

>Is this REALLY true?

>I'm curious, because the original StarLAN was 1Mbit/S and bears the label
>"802.3e-1988 1BASE5 StarLAN 1Mbit/S Ethernet".

StarLAN 1Mbit/S is not "10BASE-T" Ethernet.  When you look at those who just
see an RJ45, they are not compatible. 

As far ast the StarLAN 10 parts, early releases of StarLAN 10 did not support
Link Integrity.  LI is defined as part of the 802.3 10BASE-T standard.  If 
you have parts that cannot turn off LI, then it may not talk to the older 10 
megabit StarLAN parts.

Rob
--
Rob Miracle                |  Internet:   rwmira01@vlsi.louisville.edu
Network Consultant         |  BITNET:     rwmira01@ulkyvx
University of Louisville   |  CompuServe: 75140,625
Louisville, KY             |  To boldy go where no one has gone before.
Newsgroups: comp.dcom.lans.ethernet
From: chrisc@ramrod.lmt.mn.org (Chris Cox)
Subject: SQE
Organization: LaserMaster Technologies, Minneapolis, MN  USA
Date: Wed, 22 Jul 1992 13:28:06 GMT

Probably a FAQ (although I must admit I haven't seen it A'd F!), but what 
exactly is SQE (or heartbeat if you prefer) and what advantage('s) does it 
serve if it is enabled on a LAN?

Chris

   Chris Cox  W0/G4JEC                               chrisc@ramrod.lmt.mn.org
   LaserMaster Technologies                          Tel: (612) 944-6069
   7156 Shady Oak Road                               Fax: (612) 944-5544
   Eden Prairie, MN  55344

           ----- For mail of a more social nature, please use -----

     chrisc@moron.vware.mn.org  -or- chrisc@biggus.g4jec.tcman.ampr.org
From: thad@public.BTR.COM (Thaddeus P. Floryan)
Newsgroups: comp.dcom.lans.ethernet
Subject: Re: Is Starlan really Ethernet?
Date: 26 Jul 92 23:05:33 GMT
Organization: BTR Public Access UNIX, Mountain View CA

In article <BrwKyM.67t@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes:
>Starlan is vaguely similar to 10BaseT, but is not in any way compatible
>with it.

Is this REALLY true?

I'm curious, because the original StarLAN was 1Mbit/S and bears the label
"802.3e-1988 1BASE5 StarLAN 1Mbit/S Ethernet".

There are bridges from StarLAN to the newer StarLAN-10 (at 10Mbit/S).

StarLAN has always been CSMA/CD, etc. and companies such as Hewlett-Packard
have interoperated StarLAN with "conventional" Ethernet.

I'm not "defending" StarLAN; just would like to know in what way(s) it is
not compatible [since there is a dearth of info about StarLAN].

Thad Floryan [ thad@btr.com (OR) {decwrl, mips, fernwood}!btr!thad ]
From: oberman@ptavv.llnl.gov
Newsgroups: comp.dcom.lans.ethernet
Subject: Re: SQE, Once more
Date: 31 Jul 92 15:36:49 GMT

In article <1992Jul31.124357.10781@relay.nswc.navy.mil>, tdrake@relay.nswc.navy.mil (Tim Drake - E41) writes:
> 
>    I've read all the postings on SQE I've seen in the last two
> weeks (many). I'm still unclear on a few points. SQE should
> help me find problems in faulty MAU's, but how?? Say I'm working
> on a Unix system, what command will report the error's I shoud see
> if I have SQE turned on and the MAU is faulty. In short how can
> SQE help me find problems.

You've just hit one of my big gripes with vendors. Many, but not all U*ix OSes
simply ignore the SQE error. In this environment there is little you can do
with the fact that SQE is enabled except to complain loudly to the vendor.

For those systems that do count SQE errors, something like netstat should
return the counts. SNMP is a better way to get this information.
 
>   My other confusion is if it looks like a collision to my MAU
> (the "CP collision packet" LED lights up) how does the system
> tell the difference between the "test" and an actual collision?

It's all a matter of timing. The SQE signal is generated immediately after a
packet is transmitted. During this interval the network is not (or should not)
be carrying any traffic. Since the SQE check is sent by the MAU itself, it
expects it and so does the controller.
 
>   I must admit that we turn SQE off religiosly because of problems
> we had with it being enabled and connected to repeater equipment.  

Amazing to me how many people don't read the instructions, hook up a MAU with
SQE enabled to a repeater, have it fail, and declare SQE a BAD THING to be
turned off all the time. I know of several sites that operate this way and I
think they are all crazy (or lazy).

If a driver counts SQE errors, as many do, turning off SQE has deprived you of
a significant tool for discovering network problems. If a driver does not count
SQE errors, the vendor has deprived you the tool and you should complain
LOUDLY!

R. Kevin Oberman			Lawrence Livermore National Laboratory
Internet: koberman@llnl.gov		(510) 422-6955

Disclaimer: Don't take this too seriously. I just like to improve my typing
and probably don't really know anything useful about anything.
Newsgroups: comp.dcom.lans.ethernet
From: henry@zoo.toronto.edu (Henry Spencer)
Subject: Re: SQE
Date: Thu, 23 Jul 1992 17:13:20 GMT
Organization: U of Toronto Zoology

In article <chrisc.18.711811686@ramrod.lmt.mn.org> chrisc@ramrod.lmt.mn.org (Chris Cox) writes:
>Probably a FAQ (although I must admit I haven't seen it A'd F!), but what 
>exactly is SQE (or heartbeat if you prefer) and what advantage('s) does it 
>serve if it is enabled on a LAN?

We need an FAQ list...

Heartbeat is enabled or disabled between a transceiver and its host; it is
not a network-wide thing.  If it is enabled, in the mandatory quiet gap
following a packet, the transceiver sends a short burst of "collision
present" to the host.  The purpose of this is to test the wiring and
circuitry associated with that signal, which can easily fail without
breaking anything else.  The motive is that a failure there typically
will not take down the host or the net, but will degrade net performance,
potentially badly, in a way that is difficult to diagnose and localize.
-- 
There is nothing wrong with making      | Henry Spencer @ U of Toronto Zoology
mistakes, but... make *new* ones. -D.Sim|  henry@zoo.toronto.edu  utzoo!henry
From: dos@major.panix.com (Dave O'Shea)
Newsgroups: comp.dcom.lans.ethernet
Subject: Re: 10BASE-T at home
Date: Fri, 24 Jul 92 09:36:42 EDT
Organization: Surely you jest

edwards@world.std.com (Jonathan Edwards) writes:

> I want to prewire my new house for future installation of a LAN.
> Running extra pairs for 10BASE-T seems the most flexible.
> But a post on comp.dcom.telecom states that 10BASE-T is not FCC class B, and
> in fact generates tons of RFI, making it unsuitable for home use.
> He recommends running 10BASE-2 coax (RG58) instead.
> Does anyone have any expertise or experience to share on this matter?
> Thanks - Jonathan
> 

Perhaps that explains why I feel a strange need to point North after a 
few hours in a wiring closet. :)

Switching to shielded twisted pair should make for a good reduction in 
RFI emissions.
From: STREATER@SLACVM.SLAC.STANFORD.EDU (415)
Newsgroups: comp.dcom.lans.ethernet
Subject: Re: SQE
Date: 25 Jul 92 19:10:03 GMT
 <1992Jul23.101648.1@ptavv.llnl.gov> <j_hmc5j.seifert@netcom.com>
 <1992Jul25.061712.20885@adobe.com>

In article <1992Jul25.061712.20885@adobe.com>, pngai@adobe.com (Phil Ngai) says:
>
>In article <j_hmc5j.seifert@netcom.com> seifert@netcom.com (Rich Seifert)
>writes:
>>So blame it on me. I was the design engineer responsible for all that
>>stuff in the Ethernet spec...
>
>Including the AUI connector clip...
>
>--
>My opinions are my own.

We don't use 'em. We convert everything to posts.
Newsgroups: comp.dcom.lans.ethernet
From: gburlile@magnus.acs.ohio-state.edu (Greg Burlile)
Subject: Where to find PDETHER ??
Organization: The Ohio State University
Distribution: usa
Date: Thu, 23 Jul 1992 17:50:12 GMT

I was notified of a software product that will make ODI look like a packet
driver.  I believe the product is called PDETHER.  Does anyone know where I can
get this.  I'm trying to see how to get CUTCP 2.2-D (Clarkson Univ.'s Telnet) 
to run on a Novell 3.11 or Netware Lite newtork.

Any suggestions?
-- 
+==============+=================================================+
+  T . H . E   +             Greg Burlile            Go Bucks !  +
+  OHIO STATE  +                                                 +
+  UNIVERSITY  +  Internet:  gburlile@magnus.acs.ohio-state.edu  +
From: seifert@netcom.com (Rich Seifert)
Newsgroups: comp.dcom.lans.ethernet
Subject: Re: 10basT Question
Summary: No, not quirtete
Date: 23 Jul 92 18:10:17 GMT
Organization: Netcom - Online Communication Services  (408 241-9760 guest)

In article <53020001@hpscit.sc.hp.com>, karl@hpscit.sc.hp.com (Karl Watanabe) writes:
> In comp.dcom.lans.ethernet, jonathan@netcom.com (Jonathan Ridder) writes:
> 
> > Though this is not usually done (and may not officially be supported?),
> > you can connect them with a crossover cable.  The crossover cable is
> > wired so that the receive pairs connect to the transmit pairs.  If I
> > recall,  this would be pin 1 to pin 3 and pin 2 to pin6.
> 
> The 10baseT chip transceiver from AMD automatically has polarity reversal.
> Therefore it wouldn't be necessary to use a crossover cable.
> 

No, this won't help. The polarity reversal function will correct for
a twisted pair which is connected backwards, but will not swap the
transmit and receive pairs!

(Ethernet cares about the polarity of the TP because it uses pure
Manchester encoding, which is absolute-level sensitive. Token Ring
uses differential Manchester, which is sensitive only to transitions,
and not absolute levels. So an inverted TP requires no "fixing" in
Token Ring. The tradeoff is a more complex decoder.)

-- 
Rich Seifert                    Networks and Communications Consulting
seifert@netcom.com              (408) 996-0922
                                (408) 996-2860 FAX
"... specialists in Local Area Networks and Data Communications systems"
Newsgroups: comp.dcom.lans.ethernet
From: gary@sci34hub.sci.com (Gary Heston)
Subject: Re: Mixing RG58/U and RG-59 cable
Reply-To: gary@sci34hub.sci.com (Gary Heston)
Organization: SCI Systems, Inc., Huntsville, Al.
Date: Thu, 23 Jul 1992 21:17:39 GMT

In article <10992@rls.UUCP> randy@rls.UUCP (randy) writes:

>How do you go about determining the length of thin line cable that
>wasn't installed too terribly well?  I have some cable run in a rambling
>and looping fashion throughout the laboratories.  A great deal of the
>cable is behind walls or above ceilings and we need to know what it will
>take to expand.  Anyone?

Buy or borrow a cable tester with a TDR built in (many protocol analyzers
have these as well); pull the terminator off one end, go to the other end
plug in tester, and read the distance to the open.

I use a MicroTest Quick Scanner for this; it works quite well. They can
also be used to test the amount of cable remaining on a spool (up to
2000' with the Quick Scanner). 

If all you have is an ohmmeter, you might be able to short one end, pull
the terminator off the other, measure the resistance, and compare that
with a known length (like a new spool of cable) to get a rough estimate.
You'll only see a few ohms over a several hundred foot length, though, 
and would need a fairly good resolution meter (and consistent cable type)
to get a usable number.

Gary


-- 
Gary Heston    SCI Systems, Inc.  gary@sci34hub.sci.com   site admin
The Chariman of the Board and the CFO speak for SCI. I'm neither.
"Always remember, that someone, somewhere, is making a product that will
make your product obselete." Georges Doriot, founder of American R & D.
Newsgroups: comp.dcom.lans.ethernet
From: swhite@tybse1.uucp (William C. "Spike" White)
Subject: Re: Is Starlan really Ethernet?
Organization: Tybrin Corporation, Shalimar, FL
Date: Thu, 30 Jul 1992 01:02:49 GMT

In article <7520@public.BTR.COM> thad@public.BTR.COM (Thaddeus P. Floryan) writes:
>In article <BrwKyM.67t@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes:
>>Starlan is vaguely similar to 10BaseT, but is not in any way compatible
>>with it.
>
>Is this REALLY true?
>
>I'm curious, because the original StarLAN was 1Mbit/S and bears the label
>"802.3e-1988 1BASE5 StarLAN 1Mbit/S Ethernet".
>
>There are bridges from StarLAN to the newer StarLAN-10 (at 10Mbit/S).
>
>StarLAN has always been CSMA/CD, etc. and companies such as Hewlett-Packard
>have interoperated StarLAN with "conventional" Ethernet.
>
>I'm not "defending" StarLAN; just would like to know in what way(s) it is
>not compatible [since there is a dearth of info about StarLAN].
>
>Thad Floryan [ thad@btr.com (OR) {decwrl, mips, fernwood}!btr!thad ]

I thought StarLAN was nothing but AT&T's version of the old 1BASE5 
implementation of IEEE 802.3.  This was a baseband implementation of 
IEEE 802.3 that ran over unshielded twisted pair.  As I recall, its main
drawback was that it only ran at 1 Mb/sec, while the other IEEE 802.3
implementations ran at 10Mb/sec (10BASE5, 10BASE2, 10BROAD??).  And 
from what I read, it seems that 10BASET is nothing more than a 10Mb/sec
version of 10BASET.  In fact, I recently had an AT&T X-terminal
w/ a 10BASET port, and a 10BASE2-to-10BASET convertor.  However, the name
on the pieces was "StarLAN-10",  so it seems AT&T is still in the 
"Ethernet Obfuscation" business.


-- 
Spike White     Tybrin Corporation, Shalimar, FL | Moderation in all things --
swhite@afseo.eglin.af.mil                        | and abstinence in none! 
Disclaimer: I speak only for myself, not my employer.
From: john@iastate.edu (John Hascall)
Newsgroups: comp.dcom.lans.ethernet
Subject: Re: Early and Late Collision
Date: 30 Jul 92 00:36:41 GMT
Organization: Iowa State University, Ames, IA

henry@zoo.toronto.edu (Henry Spencer) writes:
}Once the necessary time for consensus has elapsed and no collision has
}been seen, all nodes should agree that there is a transmission in progress.
}A properly-functioning Ethernet node will not attempt to transmit between
}seeing that somebody else is transmitting and the end of that transmission.
}A late collision is one occurring after consensus should have been achieved.
}It means something is badly wrong somewhere -- either a misconfigured
                                                         ~~~~~~~~~~~~~
}network or a malfunctioning node.

Most likely a segment longer than the longest allowed.

John
-- 
John Hascall                                       ``Live with it pink-boy!''
Project Vincent                                                              
Iowa State University Computation Center                     john@iastate.edu
Ames, IA  50011                                      515/294-9551 [fax -1717]
Newsgroups: comp.dcom.lans.ethernet