link aggreation 2748 power connect

I have two Dell Power connect 2748 switches, and I want to do link aggreation between the two switches.  

One switch is in my server room, and the other switch in another part of the office.  Instead of 1 Gigabit of connection between the switches I would like to have 4.

I went into the web interfaces of both of the switches and clicked ON LAG membership.  I started with two ports connected up the switches and got a traffic storm.  I am missing something here.  I went to the Dell site to look for a step guide but I was not able to find anything.  I really would appreciate a little help.

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Page 52 shows LAG configuration.
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1. are the ports configured on both switches?
2. are there any other switches/hubs in between?
--some installations have hidden equipment to overcome long runs or breaks in lines, or just as a local tap.
rarnold_6951Author Commented:

Both ports are configured on the switches, and there is nothing between.  

I found the documentation in the interm after a little more hunting, and that is exactly the way it is setup, but I still  get an IP storm.  Do I need to use a cross over cable to make this work?
No.  Straight through cables for both connections.

Have you looked for other equipment in between the endpoints?  These would (of course) not be configured for the LAG, and would cause the problems you see.

Another thing to consider...the settings are supposed to take place as soon as you hit "Apply", but is there a "Save" function?  In some switches (like my Netgears) you can apply changes to the config, but upon re-boot they are lost.  You have to go to another screen in the admin/system area to hit "Save Config".

Also, did you try cold booting the switches after the config change?  Good thing to do for:
1. verifying the config is saved
2. peace of mind knowing that a power outage/resumption won't take your network because of an unsaved config.
rarnold_6951Author Commented:
I checked again.  There are pass though cables connect that just the two switches in the two port numbers indicated.  Am I doing somthing that is not supported by these particular switches?
>Am I doing somthing that is not supported by these particular switches?

No.  LAG is fairly common for joining remote switches, or adjacent switches that lack dedicated stacking cables.

LAGs can also be used for faster server-to-switch connections.

Try this troubleshooting:
Assume Switches A & B, using ports 1 & 2 for LAG group:

With Cable#1
Connect A1 to port B1.
Connect port A2 to port B2.
Connect port A1 to port B2.
Connect port A2 to port B1.

Repeat same with Cable#2, 3, 4.

Any problems with this yet?  This should eliminate cable problem or port malfunction as cause.

Now, connect Cable#1(A1-B1) and Cable#2(A2-B2).
When storm starts, swap Cable#2 with Cable#3.
Still have the problem? --> Replace Cable#2.  Swap Cable#1 with Cable#3.
If swapping Cable#1 or Cable#2 with Cable#3 fixes the problem, there may be a hidden repeater somewhere on that line.

Another thing to consider...have you updated firmware on these switches to the most current?  If you call tech support, they will recommend this, no matter what the problem.

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