Trunk Mode??

Question

i have read a few posts about connecting 2 switches together and they were using 'Trunk Mode'. Can someone explain what this is please? thanks Nigel

ProductManager · Answer

NigelRobson,   Trunking can mean one of two different things.   1) It can mean bonding multiple ports together to create a 'fatter' pipe 2) It can mean assigning multiple VLANs to a port   It you will let me know which of these you mean, I can point you to appropriate documentation as it relates to specific products.   ++++ProductManager++++

NigelRobson · Answer

I have 2 x 6248 switches that need to be linked over a distance of 150m. i was wanting to use fiber and link aggregation to do this. We could get away with a single fiber cable but having them linked would be nice. i really could do with some simple steps on how to set this up. is it just the case of adding the 2 fiber ports to a LAG and thats it? thanks Nigel

ProductManager · Answer

'is it just the case of adding the 2 fiber ports to a LAG and thats it?'   Yes. That's it. The manuals to assist you configuaration can be found at:   http://support.dell.com/support/edocs/network/pc62xx/   ++++ProductManager++++

NigelRobson · Answer

i saw the manual but to be honest it confused me, I'm pretty new to the more advanced settings for switches Nigel

Adam N · Answer

glad you asked that question :)   Take a look at the following paper which describe exactly how a LAG works:- http://www.dell.com/downloads/global/power/ps2q05-20040286-Holmes-OE.pdf   Basically, a LAG does increase bandwidth beyond the bandwidth of a single port but it depends greatly on the traffic pattern.   Traffic for a singe flow (between a given source and destination) always traverse the same port  in the LAG.   If you have multiple flows between different ends (the flow is determine by the MAC of the source & destination in a particular way - see the paper) then these flows are distributed between all ports within the LAG.    So if you have lots of different traffic flows from different source and destinations then all those flows are distributed through the ports within the LAG so you do overall increase the bandwidth capacity of the link.

Adam N · Answer

Hello Nigel,   To create a LAG from the CLI, the commands are:   channel-group 1 mode auto   - this creates a LACP LAG   Or   channel-group 1 mode on  - this creates a static LAG   So, all you need to do is go into each port you wish to be a member of your LAG and enter either of the above.  If you want ports to participate in different LAG groups then you just increment the channel-group number.   Hope this helps

Adam N · Answer

correct, i am talking about your client and servers.

NigelRobson · Answer

Nice, sounds like it will us down to the ground thanks for all your help today, much appreciated! Nigel

NigelRobson · Answer

when you say source MAC and Destination MAC, will they be the Client PC's talking to the servers and not actually the switches ports? i'll read that link now thanks Nigel

Adam N · Answer

yes, that is correct.

NigelRobson · Answer

Brilliant! thats just what i needed to know. so by using this method over 2 fibre channels, will i effectively get 2Gbps? Nigel

NigelRobson · Answer

and from the web interface i just select the ports from the LAG sub menu and put a '1' in there if i want it to be a member of LAG1? is this correct?

StarLog · Answer

Adam, Sorry for highjacking this thread, but does this work equally as well on a Dell server with Broadcom dual NIC's.? I looked at the traffic on both ports, and noticed that one had much more traffic then the other. Thanks

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