Server Fault is a question and answer site for system and network administrators. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I work in Unified Communications for a company with about 9000 desktops and laptops. I'm part of a team who is implementing and supporting things like Lync and Jabber Video and audio conferencing.

While troubleshooting some pretty constant call quality problems from users who are out of the office, it's come to my attention that our all our desktop and laptop network connections are hard coded to 100full...

Doesn't this mean that any time one of our 2000 laptop users are out of the office and plugs into the internet somewhere that they will experience a duplex mismatch??? My understanding is yes. I also understand that this is very very bad for video and audio conferencing...

I've spoken to a number of people in our Networking team and am unable to convince them to look at switching over to an Autonegotiated environment.

I need help with either a)Finding or putting together sufficient evidence that we need to make a switch, or b)Finding another way to make the duplexing match correctly while users are offsite(users do not have access to change link speed).

Thanks for any help you can provide, Shawn

share|improve this question

Well first off it's pretty much hopeless troubleshooting VoIP (or voice-video, etc.) call quality problems if the client isn't on your network: The second the packets left your edge you lost all meaningful control, and you have no idea what kind of bandwidth is available or how traffic shaping is being applied on the foreign network.

There are things you can do, but that's outside the scope of this question -- Ask a new one and tell us what troubleshooting you've already done, what softphones/other software you're using, etc. and maybe we can give you some ideas.

As to the autonegotiation thing, I think best practices these days are to have all your ports set for autonegotiation, and to only disable it for specific ports/systems if autonegotiation is failing for some reason. There was some discussion about this 2-3 years ago right here on Server Fault, but even then the anti-autonegoation folks seemed to be in the "Because it used to not work" FUD camp -- the general consensus seemed to be "Turn autonegotiation on, and fix anything that stops it from working."

You would only have a problem at other locations if the client machine (laptop) is set for a specific speed/duplex setting (which may or may not be the case), but if they're hard-coding the switch they're probably doing it to the laptop as well. It would be hard to judge the impact of this without empirical testing (at multiple remote sites), but it probably wouldn't be a Good Thing if you plugged in to a mismatched port.

share|improve this answer

Technically, yes there could be a problem. If the other side of the connection is set to auto, and fails to negotiate, it is required to fall back to half duplex. However, most decent network adapters report statistics, and the mismatch would manifest as errors like crc or dropped frames on the mobile device.

It is fairly common to hard set both ends of a connection in a physical premises that you control, but that is not a viable strategy with mobile devices that could be anywhere.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.