[K12OSN] OT: parallel running cat5e to switches

"Terrell Prudé Jr." microman at cmosnetworks.com
Sat Feb 21 15:46:25 UTC 2009

Sure, we do this all the time at work.  What you're describing has many 
names--Cisco calls it EtherChannel; everyone else calls it MultiLink or 
ChannelBonding.  We use EtherChannel quite a bit in our data centre.

What it does is bond two ports together on a switch to act like a single 
port.  And yes, your bandwidth does double (the overhead is less than 
1%).  It needs to be configured on both switches, but it's not hard.  
So, in your situation, you'll go from 1Gbps to 2Gbps.

That said....

The channel bonding will double your bandwidth on *that* line, but 
that's all it will do.  If your video server has only a 1Gbps link, then 
you'll see no throughput increase to that server.  On the other hand, if 
you've got two or three such high-bandwidth servers with (in this 
example) 1Gbps connections, all of these servers are on one of these two 
switches, these servers's own links aren't otherwise pegged, *and* all 
the clients are also on one of these two switches, then yes, you will 
see a bandwidth increase.  Oh, and your servers need to have enough 
oomph to actually be able to pump that kind of traffic.

If you've got only one high-bandwidth server, and its line is pegging, 
then you would be well advised to put it on a Gig-E MultiLink as well.  
Linux supports this.

In short, you've really got to think about where all your bottlenecks are.

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Microsoft Free since 2003 <http://www.cmosnetworks.com>--the ultimate 
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Barry R Cisna wrote:
> Hello List,
> Has anyone here done any real 'bean counting' studies in regards to how
> much,if any gains can be had by parallel running cat5e's from switch to
> switch. In other words running two cat5e's from say the server room
> switch to a room that gets heavy video use? This would be to use our
> existing hardware/switches .We currently have GIGE backbone with uplink
> ports at each 'hallway' switch,from there going into each class room is
> fed with 10/100 ports. I am guessing bottom line the throughput gain
> would be very marginal for all the work involved.Also trying to figure
> out if we was to do this how to conglomerate the second wire with only
> two uplink ports for each switch? (The second port on each switch feeds
> down to the next hallway switch).Not all homerun cat5 runs here:(
> We are fed with one T1 line and a second dsl for teaches/office people's
> pc's.
> We have two classrooms that are physically 600ft from the server room
> but goes through one 'junction hallway' switch so distance is still
> within reason,but you might know these are the two most used computer
> labs and sometimes i get complaints of 'being  slow'.
> Just wondering if anyone on list here has done this,and if so,if it was
> worth the trouble?
> I have Googled and cant not find any graphs,or anything to document
> this. Seems odd?
> Thanks,
> Barry Cisna
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