Using a sniffer with a 3Com 4250T Switch

[SSelke]

I need to be able to use a sniffer to monitor all the ports on a 3Com 4250T switch. Is this possible, and if so, how do I configure the switch to make this happen?

If it can't be done due to limitations on the 4250T, I would like to know that as well so I don't pursue this any further. I found instructions on how to do this on a SuperStack II 3300 switch (see thread 545-425606), but have had no luck with the 4250T.

Thanks!

 

[passerini]

Hi

I had the same Problem and contact our supplier and the answer was:
they don't know exactly but they thought that this "feature" is not implemented!!!! And they will call me if there is a solution for that problem (but no call until know)

On the 3300 you can easely turn this on...

I put a hub between the 4250T and the Sniffer Software then it works.

Do you experience some speed Problems with more than one 4250T Switch connected eachother? I have some "funny" things that I found out...
When I copy a file (30 MB) from a local PC to a Novell File Server it tooks about 2 minutes!!! If I copy the same file to a W2k Server it tooks only 20 seconds... We told this 3Com but know answer until know.

Regards
Patrick

 

[TimRegester]

The roving analysis feature is not in the code for the 4250 switch on purpose. Including it increased the cost of the switch to develop thus increasing the price. The 42xx series is the budget version of the 44xx switch range that does include the feature. If this was a feature you needed you should have specified it when you bought it and thus would have spent more money on the kit in the first place.

As for the Novell v W2K test try both tests using ftp to eliminate protocol differences, it may just be that the Novell server is less efficient (which would surprise me but is possible)

 

[SSelke]

Patrick,

No known performance problems on my group of 3 4250T switches, plus 1 4900 Gigabit switch. We are an all-Windows environment and enjoy excellent performance from our backbone.

On your Novell situation, are you running IPX or TCP/IP?

I too called 3Com Technical Support and they were able to tell me that port mirroring does not exist on the 4250T switch. Rather disappointing...

 

[passerini]

We use only TCP/IP on the Novell no IPX yet.

3Com is looking for a solution and we will see what happens...
We tried with other switches and its working fine, no Idee why this happens.
The funny thing is, if we connect a 3300 Switch with a 4250T together everything ist working fine, but with 2 4250T we have this problem.

I hope 3Com is giving us a solution soon.

 

[awj]

It's not possible to use roving analysis to monitor all ports on the switch, think about it, if you try and monitor using a 100Mb port, but try and mirror 10 other 100Mb ports you have a 10:1 contention no switch can do this. Also this has an overhead on the CPU, the main function of a switch is to move traffic around from a to b. Roving analysis, port mirroring is just a quick feature to allow you to monitor a single port if you have a problem.

You don't have the right product for what you need, I suggest that you buy a 10/100 dual speed hub if you want to monitor every connection.

 

[passerini]

We got an answer from 3Com about the Problem wiht the speed. They told us that the internal puffer of the switch is to low to manage packages above a specific size...
We have to use the 4400 Series Switch for our environment, he can handle this.

So we never buy a 4250T Switch!

 

[SSelke]

Thanks to all for helping to answer my question. In fact, I did not purchase these switches, I inherited them. It's too late to return them, so I'm stuck with them until their life-cycle expires. I'll just have to do things the hard way until I can justify replacing them.

Thanks again.