[c-nsp] FE switchport output drops

[Church, Charles]

Ras,

	Do the speed and duplex match on both sides?  Does the Juniper
interface give you any clue what's going on?  Any output errors on the
Cisco side?

Chuck

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Ras
Sent: Monday, June 25, 2007 8:48 AM
To: c-nsp
Subject: [c-nsp] FE switchport output drops

I've got a 4506 with a WS-X4148-RJ in it. One of these FE ports connects
back to a router (Juniper M7i in this particular case).

The port is experiencing an enormous amount of output drops (around
200pps) even though the average traffic (load-interval 30) is only
hovering around 15-20Mbps/4kpps.

I've tried SPANing the port to a sniffer on a gig port (to avoid packets
getting nuked on the drop..) over a couple of minutes (during which the
output drops increased significantly) but can't even find any
micro-spikes that would explain this.

Does anyone know what good next steps are to troubleshooting this? I'm
looking to move some traffic off the link as a preventative measure
(this is causing TCP havoc) which might help mitigate the problem but I
just can't for the life of me figure out why I'm seeing so many drops
with such a low traffic load and no visible micro-spikes.

I've had a look at the Cisco troubleshooting guide
(http://www.cisco.com/en/US/customer/products/hw/routers/ps133/products_
tech_note09186a0080094791.shtml)
but that hasn't been an awful lot of help.

Thanks,
Ras
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