High Drop Rate, is this normal in this situation?

[Cham Dor]

Hi,

I have a ProCurve 5406zl with 72 gigabit hosts attached to it, with two ports having a large number of drops Tx packets(~4,818,078). The hosts attached to these two ports are NFS servers (DL380's) that receive a large amount of write traffic from the other 70 hosts attached to the switch.

My question is is this drop rate seem normal? As a percentage it doesn't seem high ( Unicast Tx : 2,069,990,077 ) but the folks that monitor the network traffic claim the dropped packets are way to high.

Are there other reasons other than misconfiguration that the packet drop would be large ( e.g. I assume there is only so much buffer space on the 5406zl, would it drop after the buffers fill? Is there a way to detect that condition? )

Using "ifconfig" on the hosts in question I don't see any drops,overruns, errors, etc.

Thanks for any assistance.

-Cham

Here is the output from show int on one of the ports in question:


Port Counters for port C18

Name : stor

Link Status : Up

Bytes Rx : 2,820,671,298 Bytes Tx : 3,370,764,929
Unicast Rx : 4,028,570,168 Unicast Tx : 2,069,990,077
Bcast/Mcast Rx : 658,465 Bcast/Mcast Tx : 37,823,169

FCS Rx : 0 Drops Tx : 4,818,078
Alignment Rx : 0 Collisions Tx : 0
Runts Rx : 0 Late Colln Tx : 0
Giants Rx : 369 Excessive Colln : 0
Total Rx Errors : 369 Deferred Tx : 0

[rick jones]

Probably should be asking over in the switches section rather than HP-UX networking :) but based on the stats you give, I would guess that it is indeed the buffers filling from traffic - since it is the tx to the DL380's I would then guess it is from writes from the clients to the NFS server(s). The old many feeding into one bit...

You might consider setting-up a trunk/bond/aggregate between the 5406 and the DL380(s) to increase the aggregate capacity into the server(s). That, or consider an upgrade from gigabit to 10Gig :)

[Yogeeraj_1]

hi Cham,

The Drops Tx value represents about 0.1% of Bytes Tx.

Are there any other ports statistics that you can compare these values with?

What is the nature of the traffic?

kind regards
yogeeraj

[Steven E. Protter]

Shalom,

If your network is not busy, the drop rate is very unusual.

If the network is overloaded, as I suspect it is, then its perfectly normal, its a problem that might need to be solved.

I remember when my former employer used a procurve router. The results were far from impressive under heavy load. We eventually migrated to Cisco.

SEP

[Cham Dor]

Hi, I moved this to the networking forum so I closed this thread. Thanks for the ideas, I will try some of the items mentioned and followup with the results.