Hi All,

The network is basically dual 6509 cores, with a variety of 35xx, 37xx, 45xx switches trunked to the 6509s, and in some cases, stackables trunked to other stackables.

Today, after 3 days of watching the packets counts on various trunk ports topping out between 30,000 to 60,000 pkts/second, having the security cameras going up and down, cutting back on un-needed vlans everywhere I could think of, it finally (so late, I know, should of been one of the first things I did...) thought to check interface errors.

Found we were getting huge numbers of OutDiscards on the 6509 trunk ports.  Cleared the counters, the discards mounted up again, numbers in the 6 & 7 digit range within half an hour.

Further investigation revealed huge numbers of XMit errors on a 3550 that trunks to one of the 6509s.  XMit errors were occuring in the 6 & 7 digit figures on all connected ports.

Cleared those counters, and saw the 6 digit XMit errors within 60 seconds on two of the 3550 ports.  (All other connected ports were showing XMit errors in the 5 & 6 digit arena within 5-10 minutes.)

Those two ports where the XMit errors re-occured within 60 seconds were trunks.

One went to a 2955 that has nothing attached.  So I did a "shut" on that port.

The other, a FastEthernet port, was a trunk to a 3560.  That 3560 is in my personal office.  Last week I finally got around to connecting that 3560 to the network with a Gig port, but I left the FastEthernet trunk connected as a backup.  Today, seeing the XMit errors, I pulled the FastEthernet to the 3560 in my office.

From that point on (3 hours ago), XMit errors on the 3550 are at 270 for 1 port.  All other ports are 0 errors.

And, OutDiscard numbers on the 6509 trunks remain at 0 for all ports.

So, was it the dual trunking of my office switch that was the problem?  Because you can't dual trunk a switch with different speed links?  I would have thought that spanning tree would pick up the faster link, and that would be that.

If anyone can educate me, so I know what not to do in the future, it would be much appreciated...

Linnea