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High Drop Rate, is this normal in this situation?

Cham Dor
Occasional Contributor

High Drop Rate, is this normal in this situation?

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
4 REPLIES
rick jones
Honored Contributor

Re: High Drop Rate, is this normal in this situation?

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 :)
there is no rest for the wicked yet the virtuous have no pillows
Yogeeraj_1
Honored Contributor

Re: High Drop Rate, is this normal in this situation?

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
No person was ever honoured for what he received. Honour has been the reward for what he gave (clavin coolidge)
Steven E. Protter
Exalted Contributor

Re: High Drop Rate, is this normal in this situation?

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
Steven E Protter
Owner of ISN Corporation
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Cham Dor
Occasional Contributor

Re: High Drop Rate, is this normal in this situation?

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.