Re: NIC question & troubleshooting|
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Posted by ps56k on January 30, 2009, 11:09 am
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> Jeff Liebermann wrote:
>> wrote:
>> >>> Caught me, I was trying to decide whatever result it presented referred
>>> to what direction relative to one of the hosts to help me decide what to >>> look at. >>
>> Good question, but an obvious answer, which you already supplied. >> >> Hint: If you have a problem that needs solving, then please supply: >> 1. What problem are you trying to solve? >> 2. What hardware and software do you have to work with? >> 3. What have you done so far and what happened? >> >>> I am troubleshooting a general speed issue and isolated it to the wired
>>> LAN speed from the server which is highly asymmetrical. >>
>> I've seen this literally dozens of times. Lots of causes ranging from >> bad NIC's, NWAY negotiation failure, CAT5 cable wiring problems, >> connector failure, media converter failure, hung ethernet switch, >> full/half duplex problems at the NIC, overly busy server, etc. I'm >> going to be my usual obnoxious self and not offer any more until you >> disclose what hardware you're working with and how you're doing the >> iperf testing (specific command line incantations). That's because >> UDP and TCP testing often yield very different results. >> > just vanilla TCP using iperf -c <server IP>
>>> iperf reported 300 kbit in one direction and 70 Mbit in the other
>>> direction just working on the wired 100 Mbit LAN using my notebook and >>> also another server for testing. >>
>> Wrong on both numbers. I consistently get 90-95Mbits/sec from a >> 10/100baseT ethernet switch. Obviously, the 300Kbit/sec is also >> wrong. You might try removing the intermediate switch, grab some >> known good CAT5 cables, and go directly from the "other" server and >> your notebook. Also, check the settings on the ethernet port on both >> machines. You can sorta create the problem by having one set to full >> duplex, and the other to half duplex. >> >> Replace the cables, test server, and/or switch, one at a time, until >> the problem evaporates. It's called troubleshooting by substitution. >
> Agree, it is a remote location and I simply ran out of time because of an > ice storm that was closing in. I replaced the cables and have a GigE > switch on order as a replacement. > > >>
>>> Updating NIC drivers and turning off scalable networking brought the low
>>> speed up to 5 Mbit which is still lame. >>
>> It shouldn't make any difference. Since updating the driver has such >> a derastic effect, you might consider the possibility that the >> unspecificed device with the NIC card is having a bad day. It could >> be busy from some errant process. It could have a bad NIC. >>> The server has a GigE card
>>
>> Any particular model number GigE card? >
> Its a Dell Poweredge 1950 with dual onboard Broadcom Net Extreme II NICs. > I configured the other NIC and switched over to it but there was no > difference. > >>
>>> and there is a 100Mbit unmanaged switch.
>>
>> Maker and model? Yeah, I know I'm demand a lot by asking you to >> supply such details. However, there are some boxes out there that are >> little better than defective. >> >
> It is a D-link something (can't read my notes) > >>> Forcing link speed on the server to various auto/full/half didn't make
>>> much difference. >>
>> Forcing it where? At the server? At the laptop? With a mechanical >> switch on your unspecified unmanaged switch? >
> At the server. > >>
>>> I suggested they replace the switch with a GigE switch which makes sense
>>> because there are two servers with GigE capability. >>
>> Yeah, that makes sense if the intermediate wiring is 1000baseT >> qualified? What manner of cable and how long? >
> The switch is right above the servers so only short patch cables are > needed. > >>
>>> I think the server NIC just doesn't like talking to the switch.
>>
>> I also don't like talking to people and devices that I know nothing >> about. >> >>> The server had a second onboard NIC and I switched to it and also tried
>>> various switch ports and it didn't make a difference. >>
>> Try a 2nd laptop in place of the server. See if the unspecified model >> GigE switch is the problem. >>> I have tried switches like -d but it simply gives both results leaving
>>> you to wonder which is what. >>
>> If you have both directions, does it really matter which is which as >> long as they're the same? Methinks you're avoiding the problem. >> >> Your question has absolutely nothing to do with wireless or wireless >> internet. You might consider asking the same question (with the >> missing details supplied) in one of the networking newsgroups. >> >> > Yes, thank you much for your interest and suggestions. I didn't go into
> big details initially because I just wanted to understand what iperf was > telling me. | |||||||
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