5500G-EL discards on cascade ports

[gmarshall7000]

We have two 5500 switches stacked with cascade links at the rear. Two of these links between the two switches show a high number of "discards" when using Solar Winds network monitoring software. Is this a problem? The cpu's of these switches are showing as less than 40% busy

[Matt_M]

on my ports that I intentionally have stp blocking (or rrpp blocking) the discards are super high, but on-purpose.

fwiw...

Matt

[gmarshall7000]

I'm thinking that the discards are there purely because the ports are being blocked by spanning tree protocol.

3Com Network Director does not show any problem in this area

[philbrockbank]

Just to flesh this out a bit

2,500-2,800 discards per minute

Two switches connected via cascade ports A1->B2 and B1->A2 

CPU rarely drops below 40% on the 5 minute counter

Buffers seem to be 97-98% used at any moment in time (querying OID 1.3.6.1.4.1.43.45.1.6.1.2.2.1.4)

Ethernet ports showing no real load to speak of (mostly sub 1%)

Servers have two network cards in set up as a team, one card to each switch

Couple of theories so far, buffers - just not enough of them and ingress/egress with the multihomed servers and traffic being sent accross the switches when it thinks they are 'local'.

So, overall

1: is the amount of discards anything to be worried about

2: how do we find out what they are? (and how can we clear them?)

3: is it just running out of buffers? 

TIA

Phil

[Neil Read]

Did you resolve this issue?

I also have two 3com 5500g switches with high recieve discards.

Not sure if it's missing VLANS on some of the ports, faulty cables or just miss reporting within Solarwinds.

[manuel.bitzi]

Hi all

Thats a normal behavior in xrn/irf-ring-topology. Let me explain:

In a ring topology you have redundant ways. XRN/IRF send hardbeat-packet in both directions for redundancy checks. the second one receiving on the master device will be dropped. unfurtunatly this drop is reported as discarded by FFP (Fast Forwarding Processor) => display packet-drop.

I discussed this several times with R&D and tech support, but it doesnt seam important for them. "It works as designed"

br

Manuel