[nsp] dot1q causes port error?

Stephen J. Wilcox steve@telecomplete.co.uk
Tue, 26 Nov 2002 10:41:56 +0000 (GMT)


MPLS isnt enabled on this .. I have seen similar tho where MPLS is enabled
however on the switches where I saw it the giant counter increased only, not
crc's etc 

Steve


-- 
Stephen J. Wilcox
BSc (Hons).  CCIE #10730
Technical Director, Telecomplete
http://www.telecomplete.co.uk/

On Tue, 26 Nov 2002, Tomas Daniska wrote:

> 
> is it possible that you send larger frames to the interface (such as
> those with mpls tags)?
> 
> i'm sure on this for 3524XL and believe that it also applies for 2924 -
> it's a problem that came due to stretching mtu. originally, the ethernet
> controllers used did not support baby giants. since some release (i
> don't remember exatly which one) the cisco folk managed to tweak the
> controller microcode so they are supported now but they were unable to
> change the hardware routines for crc computation so the switches started
> forwarding baby giants but for the cost of generating false crc errors
> 
> --
> 
> deejay 
> 
> > -----Original Message-----
> > From: Temkin, David [mailto:temkin@sig.com] 
> > Sent: 25. novembra 2002 20:17
> > To: 'Stephen J. Wilcox'
> > Cc: cisco-nsp@puck.nether.net
> > Subject: RE: [nsp] dot1q causes port error?
> > 
> > 
> > I'm positive it's actually a problem with dot1q on the 2924's.  110%
> > positive, because I had the same exact issue two weeks ago 
> > between a URM
> > (3660 on a card) and a 2924 in a remote office.
> > 
> > AFAIK, disabling keepalives doesn't actually make the problem 
> > go away - it
> > didn't for me.  The only fix that worked for me was 
> > converting the trunk to
> > ISL.  It seems pretty obvious from the fact that the counters 
> > are exactly
> > the same.
> > 
> > I should have looked at the bug before I sent it to you, 
> > because it's not
> > the same as what's happening here.
> > 
> > First of all, the 35xx series doesn't have the same 
> > limitation as the 2924.
> >  Give it a shot if you can... I'm not sure what kind of production
> > environment you run.
> > 
> > 
> > 
> > 
> > > -----Original Message-----
> > > From: Stephen J. Wilcox [mailto:steve@telecomplete.co.uk] 
> > > Sent: Monday, November 25, 2002 2:13 PM
> > > To: Temkin, David
> > > Cc: cisco-nsp@puck.nether.net
> > > Subject: RE: [nsp] dot1q causes port error?
> > > 
> > > 
> > > Hi David,
> > >  this is actually saying it is a problem in ISL and NOT in 
> > > dot1q, I have seen a similar reference and have disabled 
> > > keepalives. THis makes no difference tho, the errors are 
> > > there as before.
> > > 
> > > Steve
> > > 
> > > 
> > > On Mon, 25 Nov 2002, Temkin, David wrote:
> > > 
> > > > It's a known issue caused by keepalives.
> > > > 
> > > > See bug CSCdr22809
> > > > 
> > > > It's a hardware limitation on the switch.  The router sends 
> > > keepalives 
> > > > untagged and the switch can't deal with it.
> > > > 
> > > > Convert the trunk to ISL and they will go away.  I promise. :-)
> > > > 
> > > > -Dave
> > > > 
> > > > > -----Original Message-----
> > > > > From: Stephen J. Wilcox [mailto:steve@telecomplete.co.uk]
> > > > > Sent: Monday, November 25, 2002 2:00 PM
> > > > > To: cisco-nsp@puck.nether.net
> > > > > Subject: [nsp] dot1q causes port error?
> > > > > 
> > > > > 
> > > > > Hi,
> > > > > 
> > > > > I've a Cat2924-XL-EN (c2900XL-c3h2s-mz-120.5.2-XU.bin)
> > > > > connecting to a 7200 with IO-FE (c7200-js-mz.122-8.T5)
> > > > > 
> > > > > I'm running dot1q on them and seeing errors. I'm sure theres
> > > > > no cable fault and have replicated this with different 
> > > > > hardware. I'm unable to find anything in the bug toolkit 
> > > > > (which doesnt appear to support IOS for switches very well) 
> > > > > and google showed nothing useful either.
> > > > > 
> > > > > ANyone else seen this and perhaps knows the problem?
> > > > > 
> > > > > relevant counters (no others show error)
> > > > > 
> > > > > Switch:
> > > > >      Received 89 broadcasts, 1698991 runts, 0 giants, 0 
> > throttles
> > > > >      1819995 input errors, 121004 CRC, 0 frame, 44 overrun,
> > > > > 132 ignored
> > > > > 
> > > > > Router:
> > > > >      16687740 packets output, 3005655898 bytes, 299991 underruns
> > > > >      299991 output errors, 0 collisions, 0 interface resets
> > > > > 
> > > > > Note the errors occur in the direction router to switch.
> > > > > 
> > > > > Also, pinging the switch or devices beyond the switch doesnt
> > > > > appear to produce any packet loss that ought to be associated 
> > > > > to errored frames
> > > > > 
> > > > > Any thoughts?
> > > > > 
> > > > > Steve
> > > > > 
> > > > > 
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