One Direction Network Lag

WheelerAA · ‎01-17-2008

My team is working on a LAN that we inherited from an older group which did virtually no documentation. About six months ago we installed a completely new switch and VoIP system, with fiber running into Catalyst 3750 which is connected to a 2800 series gateway and 3 48-port 3500Gs.

We're hoping to implement some kind of backup and recovery for this organization, and have been testing network speed. They own a copy of Symantec Veritas, and while doing basic testing, we've noticed significant times transferring data to certain servers (they have a small farm consisting of Dells ranging from 850s to 2650s). Moving 100mb to my machine from the Veritas box will only take about 10 secs (which is still too long in my opinion), but going the opposite way will take around 48 minutes. This seems to be a problem on several of these servers, but mainly the Veritas box. Is this an issue with the Dell server that Veritas resides on, or some network problem?

Collin Clark · ‎01-17-2008

Check your switches for collisions, input errors, duplex & speed mismatches etc. To improve throughput you can try enabling jumbo frames. A sniffer might tell you if there windowing issues and the sort that the Cisco CLI can't.

HTH and please rate.

noran01 · ‎01-18-2008

Seeing as how you also added a new VoIP system, is it possible QoS is enabled on some of these server ports?

Joseph W. Doherty · ‎01-18-2008

Of the things that ceclark@wpsic.com notes, duplex mismatches are one of the most common performance killers. Usually one side is configured for auto and the other is hard configured. Occasionally, both sides are auto but it fails. If the latter, you'll need to manually configure both sides to agree.