[27218] in resnet
Re: Ethernet ports "burning out"
daemon@ATHENA.MIT.EDU (Hulley, Thomas)
Fri Jan 27 08:34:33 2012
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Message-ID: <F303CED670956C499BBC9E74F0FA24FD015A7C06CE6C@harrison.choate.edu>
Date: Fri, 27 Jan 2012 08:34:18 -0500
Reply-To: Resnet Forum <RESNET-L@listserv.nd.edu>
From: "Hulley, Thomas" <thulley@choate.edu>
To: RESNET-L@listserv.nd.edu
In-Reply-To: <CAOjAW60ZJXC0mjKRgrkax4ufAyf1NU+mRaK3VLsW9vk9z3pbPQ@mail.gmail.com>
--_000_F303CED670956C499BBC9E74F0FA24FD015A7C06CE6Charrisoncho_
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It might be something in the room or in the vicinity. Has this happened in =
that room in previous years with different occupants?
It's an extreme example, but ports in our science building would go bad if =
they used the Van de Graaff generator anywhere near the ports.
Static electricity can zap them.
Tom Hulley
Choate Rosemary Hall
From: Resnet Forum [mailto:RESNET-L@LISTSERV.ND.EDU] On Behalf Of Joe Roth
Sent: Friday, January 27, 2012 8:18 AM
To: RESNET-L@LISTSERV.ND.EDU
Subject: Re: Ethernet ports "burning out"
Brad,
Did the students ever trade patch cables or ports in the room? It would see=
m like a rare coincidence that BOTH students computers would be damaging po=
rts on your switch at the same time. I would lean more toward one student P=
C breaking one of the ports, then them grabbing their roommates patch cable=
or moving their patch cable to the other port within the room, tuis damagi=
ng both ports. Have you asked them if they have done this? This may narrow =
your search down to just one student machine causing the issue.
How are the phone pairs run into the room (if they exist)? Are they termina=
ted anywhere near the ethernet runs? i.e. cabling run to a 66 block, etc.
Have the students in the room been attempting to use any other piece of equ=
ipment with the network other than their two PCs?
On Thu, Jan 26, 2012 at 11:36 PM, Isaac Holmes <iholmes@nd.edu<mailto:iholm=
es@nd.edu>> wrote:
Your mentioning the location of the jack near the bed reminded me of an inc=
ident we had a number of years ago with in a dorm room. Being that the jac=
k is on one side of the room and the students always seem to want the compu=
ters on the other side of the room they have 30-50 foot cables strung aroun=
d the room.
This particular room the jack failed repeatedly over move in week. When we=
went to the room to investigate we found the 30' cable strung around the f=
loor of the room and when I was pulling it up to inspect it I found the cab=
le had ended up under the leg of the metal bed frame. As it turned out the=
re was also a short extension cord right next to it. As I went to move it =
the leg of the bed cut through both the network cable and the extension cor=
d. Nothing like popping a circuit breaker and turning off power to half th=
e floor of the dorm.
After replacing his cable and making sure it no longer was being cut by the=
bed we had no more issues with that room.
Isaac Holmes
Client Engineering Specialist
OIT Distributed Engineering Support
University of Notre Dame
B036 IT Center
(574) 631-3254<tel:%28574%29%20631-3254>
-----Original Message-----
From: Resnet Forum [mailto:RESNET-L@LISTSERV.ND.EDU<mailto:RESNET-L@LISTSER=
V.ND.EDU>] On Behalf Of Brad Coburn
Sent: Thursday, January 26, 2012 11:11 PM
To: RESNET-L@LISTSERV.ND.EDU<mailto:RESNET-L@LISTSERV.ND.EDU>
Subject: Re: Ethernet ports "burning out"
Thank you all for your ideas, comments and support.
Facilities replaced the cable this afternoon, tech re-terminated everything=
and confirmed data is flowing, so now we wait.
If the problem recurs, we will separate the connections between two closet =
switches. Not that I want dead ports on two switches, but maybe the isolati=
on will be sufficient to show us something.
Next after that will probably be to patch them back into the desktop Netgea=
r in the closet. I prefer to keep any equipment locked up and out of the ha=
nds of the students.
The switches are Extreme Networks, Summit 200-48 (old) and Summit X250e-48t=
(the new one just installed).
Let me toss this out there: What does anyone think about (severe) ESD
being a possibility? It's winter time, humidity is low. The bed is right
next to the jack. Maybe a large charge developed between PJs and bed
covers? Like most of us, I get some nasty shocks this time of year. I
think it's a stretch, but if you're writing a paper while lounging on
the bed, no power supply connected, and happen to get up or sit down and
touch that patch cord, or even just the machine, perhaps the UTP
connection is a good enough drain for a large static build-up? Or
another way to ask this, is why would this NOT be a serious
consideration? (Besides about 3500 students in residence who haven't
have this problem on a regular basis over almost 20 years?) LOL
In the meantime, to some of the suggestions and comments:
* Did the ports recover after they were unused for a while, or
were they blown? (and similar thoughts about enabling/disabling ports)
--The Extreme SE recommended toggling the port enable. No change. I even
tried looking in the log to see if maybe the switch detected station
link up but wasn't able to respond. No dice. The switches that have had
port problems in the past don't experience "reanimation" (unless someone
mis-diagnosed the problem and incorrectly tagged the port bad). Very old
models cascade failure to 4- and 8-port groups when the ASICS finally
go. Our experience with port failures on switches in other buildings
(since we didn't always believe that a port could really "fail") is that
they're toast.
* To the vendor/TAC calls, it's something on the to-do. We have an em=
ail
for our SE and he had some off-the-cuff suggestions but nothing
groundbreaking. We have RMA'd switches with bad ports back, but all they
do is ship a replacement unit and close the call. We will try to see if
we can get someone to actually work the problem when things calm down.
* Where did you check pair to ground voltage? In the closet or
in the room? It sounds as if you have a floating ground in the room,
but if you checked voltage there, maybe not.
--Tried to check that. I have a 3M tester used for telco OSP copper
testing. Looked at tip-ring and tip/ring-ground for each pair, both
voltage and resistance. Used the TDR function, alone and comparative
(two pairs simultaneous); nothing apparent. The equipment rooms are
powered with normal dedicated circuits, maybe two; for these events no
other switches in the rack are affected.
* Can you isolate the PC and Mac on separate electrical circuits
to see which one fails again?
-- Didn't try this one, but it might be impractical. I believe the
building to be old enough that there's one 20A circuit per room. If not,
I'm not sure how to sufficiently and clearly explain the idea to them.
They do have their beds/desks on opposite sides of the room, so that
might achieve the goal.... Additional discussion around the office on
the topic of power-supply problems degrade into resignation that if
power was the problem something worse should be happening that would be
evident to the students.
* Is it an option to put an in-line circuit breaker on the port
connections?
--Definitely an option. I might have something in a back room somewhere,
otherwise I have a price for a device that might work. I only wish the
things would present an obvious fault condition; most of the devices
look like they will only fail obviously for a catastrophic event (e.g.
lightning).
* Is there a microwave, hair drier, or some other device that
may induce transients on the line? Maybe one of them has a bad power
supply.
-- Quite possible; the room is tight. However the typical room layouts
that student choose put all the appliances near the jack anyway; the
CATV port is there and the refridge/micro tower makes a nice TV stand
(if not terribly sturdy).
* Various comments about cable running past high voltage equipment or
facilities
-- There's nothing like that in the hallway ceiling or in the riser
rooms. We traced the cable through the ceiling. Hoped to find damage
where the bundles ended up against pipe hangers, but no dice.
-Brad
___________________________________________________
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To subscribe, unsubscribe or search the archives,
go to http://LISTSERV.ND.EDU/archives/resnet-l.html
___________________________________________________
___________________________________________________
You are subscribed to the ResNet-L mailing list.
To subscribe, unsubscribe or search the archives,
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___________________________________________________
--
Joe Roth
Networking Group
Binghamton University
Ph. 607-777-7528
Fax 607-777-4009
___________________________________________________ You are subscribed to t=
he ResNet-L mailing list.
To subscribe, unsubscribe or search the archives, go to http://LISTSERV.ND.=
EDU/archives/resnet-l.html ________________________________________________=
___
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To subscribe, unsubscribe or search the archives,
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--_000_F303CED670956C499BBC9E74F0FA24FD015A7C06CE6Charrisoncho_
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</o:shapelayout></xml><![endif]--></head><body lang=3DEN-US link=3Dblue vli=
nk=3Dpurple><div class=3DWordSection1><p class=3DMsoNormal>It might be some=
thing in the room or in the vicinity. Has this happened in that room in pre=
vious years with different occupants?<o:p></o:p></p><p class=3DMsoNormal>It=
’s an extreme example, but ports in our science building would go bad=
if they used the Van de Graaff generator anywhere near the ports.<o:p></o:=
p></p><p class=3DMsoNormal><o:p> </o:p></p><p class=3DMsoNormal>Static=
electricity can zap them.<o:p></o:p></p><p class=3DMsoNormal><o:p> </=
o:p></p><p class=3DMsoNormal>Tom Hulley<o:p></o:p></p><p class=3DMsoNormal>=
Choate Rosemary Hall<o:p></o:p></p><p class=3DMsoNormal><o:p> </o:p></=
p><p class=3DMsoNormal><span style=3D'font-size:11.0pt;font-family:"Calibri=
","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=3DMsoNor=
mal><span style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";colo=
r:#1F497D'><o:p> </o:p></span></p><p class=3DMsoNormal><b><span style=
=3D'font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><sp=
an style=3D'font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Resnet For=
um [mailto:RESNET-L@LISTSERV.ND.EDU] <b>On Behalf Of </b>Joe Roth<br><b>Sen=
t:</b> Friday, January 27, 2012 8:18 AM<br><b>To:</b> RESNET-L@LISTSERV.ND.=
EDU<br><b>Subject:</b> Re: Ethernet ports "burning out"<o:p></o:p=
></span></p><p class=3DMsoNormal><o:p> </o:p></p><p class=3DMsoNormal>=
Brad,<o:p></o:p></p><div><p class=3DMsoNormal><o:p> </o:p></p></div><d=
iv><p class=3DMsoNormal>Did the students ever trade patch cables or ports i=
n the room? It would seem like a rare coincidence that BOTH students comput=
ers would be damaging ports on your switch at the same time. I would lean m=
ore toward one student PC breaking one of the ports, then them grabbing the=
ir roommates patch cable or moving their patch cable to the other port with=
in the room, tuis damaging both ports. Have you asked them if they have don=
e this? This may narrow your search down to just one student machine causin=
g the issue.<o:p></o:p></p></div><div><p class=3DMsoNormal><o:p> </o:p=
></p></div><div><p class=3DMsoNormal>How are the phone pairs run into the r=
oom (if they exist)? Are they terminated anywhere near the ethernet runs? i=
.e. cabling run to a 66 block, etc.<o:p></o:p></p></div><div><p class=3DMso=
Normal><o:p> </o:p></p></div><div><p class=3DMsoNormal style=3D'margin=
-bottom:12.0pt'>Have the students in the room been attempting to use any ot=
her piece of equipment with the network other than their two PCs?<o:p></o:p=
></p><div><p class=3DMsoNormal>On Thu, Jan 26, 2012 at 11:36 PM, Isaac Holm=
es <<a href=3D"mailto:iholmes@nd.edu">iholmes@nd.edu</a>> wrote:<o:p>=
</o:p></p><p class=3DMsoNormal>Your mentioning the location of the jack nea=
r the bed reminded me of an incident we had a number of years ago with in a=
dorm room. Being that the jack is on one side of the room and the st=
udents always seem to want the computers on the other side of the room they=
have 30-50 foot cables strung around the room.<br><br>This particular room=
the jack failed repeatedly over move in week. When we went to the ro=
om to investigate we found the 30' cable strung around the floor of the roo=
m and when I was pulling it up to inspect it I found the cable had ended up=
under the leg of the metal bed frame. As it turned out there was als=
o a short extension cord right next to it. As I went to move it the l=
eg of the bed cut through both the network cable and the extension cord. &n=
bsp;Nothing like popping a circuit breaker and turning off power to half th=
e floor of the dorm.<br><br>After replacing his cable and making sure it no=
longer was being cut by the bed we had no more issues with that room.<br><=
br><br>Isaac Holmes<br>Client Engineering Specialist<br><br>OIT Distributed=
Engineering Support<br>University of Notre Dame<br><br>B036 IT Center<br><=
a href=3D"tel:%28574%29%20631-3254">(574) 631-3254</a><o:p></o:p></p><div><=
p class=3DMsoNormal><br><br><br>-----Original Message-----<br>From: Resnet =
Forum [mailto:<a href=3D"mailto:RESNET-L@LISTSERV.ND.EDU">RESNET-L@LISTSERV=
.ND.EDU</a>] On Behalf Of Brad Coburn<o:p></o:p></p></div><div><div><p clas=
s=3DMsoNormal>Sent: Thursday, January 26, 2012 11:11 PM<br>To: <a href=3D"m=
ailto:RESNET-L@LISTSERV.ND.EDU">RESNET-L@LISTSERV.ND.EDU</a><br>Subject: Re=
: Ethernet ports "burning out"<br><br>Thank you all for your idea=
s, comments and support.<br><br>Facilities replaced the cable this afternoo=
n, tech re-terminated everything and confirmed data is flowing, so now we w=
ait.<br><br>If the problem recurs, we will separate the connections between=
two closet switches. Not that I want dead ports on two switches, but maybe=
the isolation will be sufficient to show us something.<br><br>Next after t=
hat will probably be to patch them back into the desktop Netgear in the clo=
set. I prefer to keep any equipment locked up and out of the hands of the s=
tudents.<br><br>The switches are Extreme Networks, Summit 200-48 (old) and =
Summit X250e-48t (the new one just installed).<br><br><br>Let me toss this =
out there: What does anyone think about (severe) ESD<br>being a possibility=
? It's winter time, humidity is low. The bed is right<br>next to the jack. =
Maybe a large charge developed between PJs and bed<br>covers? Like most of =
us, I get some nasty shocks this time of year. I<br>think it's a stretch, b=
ut if you're writing a paper while lounging on<br>the bed, no power supply =
connected, and happen to get up or sit down and<br>touch that patch cord, o=
r even just the machine, perhaps the UTP<br>connection is a good enough dra=
in for a large static build-up? Or<br>another way to ask this, is why would=
this NOT be a serious<br>consideration? (Besides about 3500 students in re=
sidence who haven't<br>have this problem on a regular basis over almost 20 =
years?) LOL<br><br><br>In the meantime, to some of the suggestions and comm=
ents:<br><br>* Did the ports recover after they=
were unused for a while, or<br>were they blown? (and similar thoughts abou=
t enabling/disabling ports)<br>--The Extreme SE recommended toggling the po=
rt enable. No change. I even<br>tried looking in the log to see if maybe th=
e switch detected station<br>link up but wasn't able to respond. No dice. T=
he switches that have had<br>port problems in the past don't experience &qu=
ot;reanimation" (unless someone<br>mis-diagnosed the problem and incor=
rectly tagged the port bad). Very old<br>models cascade failure to 4- and 8=
-port groups when the ASICS finally<br>go. Our experience with port failure=
s on switches in other buildings<br>(since we didn't always believe that a =
port could really "fail") is that<br>they're toast.<br><br>* &nbs=
p; To the vendor/TAC calls, it's something on the to-do. We h=
ave an email<br>for our SE and he had some off-the-cuff suggestions but not=
hing<br>groundbreaking. We have RMA'd switches with bad ports back, but all=
they<br>do is ship a replacement unit and close the call. We will try to s=
ee if<br>we can get someone to actually work the problem when things calm d=
own.<br><br>* Where did you check pair to groun=
d voltage? In the closet or<br>in the room? It sounds as if you=
have a floating ground in the room,<br>but if you checked voltage there, m=
aybe not.<br>--Tried to check that. I have a 3M tester used for telco OSP c=
opper<br>testing. Looked at tip-ring and tip/ring-ground for each pair, bot=
h<br>voltage and resistance. Used the TDR function, alone and comparative<b=
r>(two pairs simultaneous); nothing apparent. The equipment rooms are=
<br>powered with normal dedicated circuits, maybe two; for these events no<=
br>other switches in the rack are affected.<br><br>* &=
nbsp; Can you isolate the PC and Mac on separate electrical circuits<br>to =
see which one fails again?<br>-- Didn't try this one, but it might be impra=
ctical. I believe the<br>building to be old enough that there's one 20A cir=
cuit per room. If not,<br>I'm not sure how to sufficiently and clearly expl=
ain the idea to them.<br>They do have their beds/desks on opposite sides of=
the room, so that<br>might achieve the goal.... Additional discussio=
n around the office on<br>the topic of power-supply problems degrade into r=
esignation that if<br>power was the problem something worse should be happe=
ning that would be<br>evident to the students.<br><br>*  =
; Is it an option to put an in-line circuit breaker on the port<br>c=
onnections?<br>--Definitely an option. I might have something in a back roo=
m somewhere,<br>otherwise I have a price for a device that might work. I on=
ly wish the<br>things would present an obvious fault condition; most of the=
devices<br>look like they will only fail obviously for a catastrophic even=
t (e.g.<br>lightning).<br><br>* Is there a micr=
owave, hair drier, or some other device that<br>may induce transients on th=
e line? Maybe one of them has a bad power<br>supply.<br>-- Quite poss=
ible; the room is tight. However the typical room layouts<br>that student c=
hoose put all the appliances near the jack anyway; the<br>CATV port is ther=
e and the refridge/micro tower makes a nice TV stand<br>(if not terribly st=
urdy).<br><br>* Various comments about cable running p=
ast high voltage equipment or<br>facilities<br>-- There's nothing like that=
in the hallway ceiling or in the riser<br>rooms. We traced the cable throu=
gh the ceiling. Hoped to find damage<br>where the bundles ended up against =
pipe hangers, but no dice.<br><br>-Brad<br><br>____________________________=
_______________________<br>You are subscribed to the ResNet-L mailing list.=
<br><br>To subscribe, unsubscribe or search the archives,<br>go to <a href=
=3D"http://LISTSERV.ND.EDU/archives/resnet-l.html" target=3D"_blank">http:/=
/LISTSERV.ND.EDU/archives/resnet-l.html</a><br>____________________________=
_______________________<br><br>____________________________________________=
_______<br>You are subscribed to the ResNet-L mailing list.<br><br>To subsc=
ribe, unsubscribe or search the archives,<br>go to <a href=3D"http://LISTSE=
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archives/resnet-l.html</a><br>_____________________________________________=
______<o:p></o:p></p></div></div></div><p class=3DMsoNormal><br><br clear=
=3Dall><o:p></o:p></p><div><p class=3DMsoNormal><o:p> </o:p></p></div>=
<p class=3DMsoNormal>-- <br>Joe Roth<br>Networking Group<br>Binghamton Univ=
ersity<br>Ph. 607-777-7528<br>Fax 607-777-4009<o:p></o:p></p></div><p class=
=3DMsoNormal>___________________________________________________ You are su=
bscribed to the ResNet-L mailing list. <o:p></o:p></p><p>To subscribe, unsu=
bscribe or search the archives, go to <a href=3D"http://LISTSERV.ND.EDU/arc=
hives/resnet-l.html">http://LISTSERV.ND.EDU/archives/resnet-l.html</a> ____=
_______________________________________________ <o:p></o:p></p></div></body=
></html>=
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