Hard Code or Auto Negotiate?

[NDJeff]

so now I have two different network engineers telling me two different things. One is telling me to set my Polycom FX and HDX 9004 to auto negotiate because of something called "Level 2" routing config... and I got another telling me to set to 100mb and Full Duplex. Is it because a lot of network eng. just dont' understand the intricacies of videoconferencing or doesn't it really matter? :confused:

[osuets]

Some swithches will only sync with Polycoms when both the port and the polycom are set to 100 full. Sometimes both sides have to be in auto, sometimes one side is 100 full and the other side is auto. Have seen issues with Extreme swithches and routers but not so much with Cisco (usually auto works). If the equipment is not talking to the switch properly and is constantly renegotiating, packets collisions can occur and the quality of signal may look like half duplex.

[Sean Lessman]

...sometimes one side is 100 full and the other side is auto.

Never, never, never do this. Either force both sides or leave both sides at auto. Never, never, never force just one side.

Sean

[Glen Sykes]

...'Level 2 Routing Config', a switch operates at layer 2 in the OSI model, and has nothing to do with routing. Was it 'layer 2' he said?

Regardless, duplex and speed settings have nothing to do with any of that!

Both endpoints have configurable 10/100 ethernet ports so you can set them either to auto negotiate or fixed. The key point here is to ensure that the speed and duplex match on both the switch and the endpoint, and it's preferable to not use auto negotiation (as although it's meant to be a standard, you can trust in the notion that devices often negotiate incompatible speeds / duplexes). I recommend you go with 100/full on both endpoints and both switch ports.

I've never come across a situation as described above, where one device is set to auto, and the other connected device on fixed, that's breaking every rule in networking as far I'm concerned. And I've yet to see 'half-duplex' quality! :confused:

Short answer, Hard Code, every time.

[Glen Sykes]

Never, never, never do this. Either force both sides or leave both sides at auto. Never, never, never force just one side.

Sean

Well said.

[whitebuffalo]

when our network was first brought up we had a fair amount of packet loss. the resolution was taking everything to 100 Full. the video contractors had hard coded everything to 100 full and the network contractor had left it to all auto. once it was all forced 100 full--no probs.

[Tallman2]

Here is one other thing to consider.. both Polycom and Tandberg are FULL Duplexing systems, so setting your network to do half would be just adding trouble.

[James Flockton]

Really, the long and short is;

Fix both the switch and endpoint to 100MB Full Duplex it makes a massive performance difference than just leaving them on Auto. I have seen improvements on every VC system v's leaving them on Auto, this rule also applies to Network VC hardware as well. If you read Cisco network documentation they tell you to fix the port speeds of every server/appliance on a data network.

[Sean Lessman]

If you read Cisco network documentation they tell you to fix the port speeds of every server/appliance on a data network.

We run auto/auto globally, works fine and I would argue we do more video than Cisco does. However, there is always a chance for some sort of interop issue as consistency among Cisco products is a little low, so forcing the protocol is also a choice. But I would say forcing should be the last resort as it is more challenging to manage from an IT perspective.

Sean

[montgomeryed]

You have to go with what works. If you're loosing packets change it until you're not...