By nature, a hub is half-duplex - it's a repeater. Besides, misconfigured duplex will not cause CRC errors. C. -----Original Message----- From: David G. Andersen [mailto:dga@lcs.mit.edu] Sent: Tuesday, January 07, 2003 2:08 PM To: Drew Weaver Cc: 'nanog@merit.edu' Subject: Re: Weird networking issue. Rule number 1 with any ethernet: Check to make sure you have the duplex and rate statically configured, and configured identically on both ends of the connection. I'd wager you've got half duplex set on one side, and full on the other... -Dave On Tue, Jan 07, 2003 at 02:19:10PM -0500, Drew Weaver mooed:
Hi, this is kind of a newbie question but this doesn't make a whole lot of sense :P
I have an etherstack hub connected to a FastEthernet port on a cisco 3660 router, these are the stats when I do a show int fast0/0:
5776 input errors, 5776 CRC, 2717 frame, 0 overrun, 0 ignored
Whats weird is I just cleared the counters 12 minutes ago, and already
there
are almost 6000 CRC errors. This connected via a standard Cat5 ethernet cable, I have tried replacing the cable to noavail.
Is this a fairly normal situation, If so that's great, but it seemed rather ridiculous to me, and if it is not a normal situation, what would cause this?
Any ideas are appreciated. Thanks, -Drew Weaver
-- work: dga@lcs.mit.edu me: dga@pobox.com MIT Laboratory for Computer Science http://www.angio.net/ I do not accept unsolicited commercial email. Do not spam me.
Heh. Tell that to my Catalyst 3548's and the E250's at the other end. ;) Lab testing showed serious throughput issues though (expected) in duplex-mismatched links, and large increases in runt and mutli-collision counters. CRC errors and FCS errors also rose in proportion to relative link saturation in a more simplistic 6500 <->7509<-> 3548 test environment.
Besides, misconfigured duplex will not cause CRC errors.
C.
-----Original Message----- From: David G. Andersen [mailto:dga@lcs.mit.edu] Sent: Tuesday, January 07, 2003 2:08 PM To: Drew Weaver Cc: 'nanog@merit.edu' Subject: Re: Weird networking issue.
Rule number 1 with any ethernet: Check to make sure you have the duplex and rate statically configured, and configured identically on both ends of the connection.
I'd wager you've got half duplex set on one side, and full on the other...
-Dave
On Tue, Jan 07, 2003 at 02:19:10PM -0500, Drew Weaver mooed:
Hi, this is kind of a newbie question but this doesn't make a whole lot of sense :P
I have an etherstack hub connected to a FastEthernet port on a cisco 3660 router, these are the stats when I do a show int fast0/0:
5776 input errors, 5776 CRC, 2717 frame, 0 overrun, 0 ignored
Whats weird is I just cleared the counters 12 minutes ago, and already
there
are almost 6000 CRC errors. This connected via a standard Cat5 ethernet cable, I have tried replacing the cable to noavail.
Is this a fairly normal situation, If so that's great, but it seemed rather ridiculous to me, and if it is not a normal situation, what would cause this?
Any ideas are appreciated. Thanks, -Drew Weaver
-- work: dga@lcs.mit.edu me: dga@pobox.com MIT Laboratory for Computer Science http://www.angio.net/ I do not accept unsolicited commercial email. Do not spam me.
Sun's hme cards won't go full duplex even though they advertise it to remote switch, causing immense headaches to anyone with Sun gear... http://www.eng.auburn.edu/~rayh/solaris/solaris2-faq.html#q4.13 -alex On Tue, 7 Jan 2003 ed@the7thbeer.com wrote:
Heh. Tell that to my Catalyst 3548's and the E250's at the other end. ;)
Lab testing showed serious throughput issues though (expected) in duplex-mismatched links, and large increases in runt and mutli-collision counters. CRC errors and FCS errors also rose in proportion to relative link saturation in a more simplistic 6500 <->7509<-> 3548 test environment.
Besides, misconfigured duplex will not cause CRC errors.
C.
-----Original Message----- From: David G. Andersen [mailto:dga@lcs.mit.edu] Sent: Tuesday, January 07, 2003 2:08 PM To: Drew Weaver Cc: 'nanog@merit.edu' Subject: Re: Weird networking issue.
Rule number 1 with any ethernet: Check to make sure you have the duplex and rate statically configured, and configured identically on both ends of the connection.
I'd wager you've got half duplex set on one side, and full on the other...
-Dave
On Tue, Jan 07, 2003 at 02:19:10PM -0500, Drew Weaver mooed:
Hi, this is kind of a newbie question but this doesn't make a whole lot of sense :P
I have an etherstack hub connected to a FastEthernet port on a cisco 3660 router, these are the stats when I do a show int fast0/0:
5776 input errors, 5776 CRC, 2717 frame, 0 overrun, 0 ignored
Whats weird is I just cleared the counters 12 minutes ago, and already
there
are almost 6000 CRC errors. This connected via a standard Cat5 ethernet cable, I have tried replacing the cable to noavail.
Is this a fairly normal situation, If so that's great, but it seemed rather ridiculous to me, and if it is not a normal situation, what would cause this?
Any ideas are appreciated. Thanks, -Drew Weaver
-- work: dga@lcs.mit.edu me: dga@pobox.com MIT Laboratory for Computer Science http://www.angio.net/ I do not accept unsolicited commercial email. Do not spam me.
On Tue, 7 Jan 2003 alex@pilosoft.com wrote:
Sun's hme cards won't go full duplex even though they advertise it to remote switch, causing immense headaches to anyone with Sun gear...
That is just not true. I've had several Sun boxes with hme interfaces properly autoneg into 100/full with misc equipment, including 3548:s, and working properly. -- Mikael Abrahamsson email: swmike@swm.pp.se
### On Tue, 7 Jan 2003 22:32:15 +0100 (CET), Mikael Abrahamsson ### <swmike@swm.pp.se> casually decided to expound upon "'nanog@merit.edu'" ### <nanog@merit.edu> the following thoughts about "RE: Weird networking ### issue.": MA> On Tue, 7 Jan 2003 alex@pilosoft.com wrote: MA> MA> > Sun's hme cards won't go full duplex even though they advertise it to MA> > remote switch, causing immense headaches to anyone with Sun gear... MA> MA> That is just not true. I've had several Sun boxes with hme interfaces MA> properly autoneg into 100/full with misc equipment, including 3548:s, and MA> working properly. Ditto. I'm currently sitting at my workstation (Sun Ultra2) and its hme0 autonegotiates fine with my Cisco 3524XL each and every time. I don't even have to pin any of the interfaces to 100/full. Admittedly I have had problems in the past, namely a bunch of E4500s to some 5000-series switches. Since they were in remote datacenters, I did pin the interfaces on both ends. -- /*===================[ Jake Khuon <khuon@NEEBU.Net> ]======================+ | Packet Plumber, Network Engineers /| / [~ [~ |) | | --------------- | | for Effective Bandwidth Utilisation / |/ [_ [_ |) |_| N E T W O R K S | +=========================================================================*/
On Tue, 7 Jan 2003, Jake Khuon wrote:
problems in the past, namely a bunch of E4500s to some 5000-series switches. Since they were in remote datacenters, I did pin the interfaces on both ends.
I've seen problems with 3548:s and Sun le-interfaces though, sometimes the link would only see packets going one way on the link, also the behaviour was different on the lower and upper row of ports on the 3548. I have never seen any of these problems with other brands of switches. We solved it by putting a dumb 10megabit hub between the Sun le-interface and the cisco switch. -- Mikael Abrahamsson email: swmike@swm.pp.se
At 10:32 PM 1/7/2003 +0100, Mikael Abrahamsson wrote:
On Tue, 7 Jan 2003 alex@pilosoft.com wrote:
Sun's hme cards won't go full duplex even though they advertise it to remote switch, causing immense headaches to anyone with Sun gear...
That is just not true. I've had several Sun boxes with hme interfaces properly autoneg into 100/full with misc equipment, including 3548:s, and working properly. -- Mikael Abrahamsson email: swmike@swm.pp.se
The behavior I've seen in the past is Sun gear negotiating properly when plugged into Cisco gear that is already running. If you power cycle the switch with the servers already attached the port will not negotiate correctly... usually to half duplex. Also I've seen duplex problems in the past week that caused, runts, giants, collisions, CRCs, errors of all sorts, kernel module reloads, vlan tagging failure, and depletion of the ozone layer. Or maybe is was reality tv that caused that ozone thing... Ramin
On Tue, 7 Jan 2003, Charles Youse wrote:
Besides, misconfigured duplex will not cause CRC errors.
Yes it will. It will cause CRC errors/RX underflows/RX frags/RX align on one end and late collissions on the other end depending on which one is running half duplex and which one is running full duplex. -- Mikael Abrahamsson email: swmike@swm.pp.se
participants (6)
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alex＠pilosoft.com -
Charles Youse -
ed＠the7thbeer.com -
Jake Khuon -
Mikael Abrahamsson -
Ramin K