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Switch question, daisy chain VS home run

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May 27, 2004 10:44:16 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

I have three switches, they are daisy chained.
Would I see better performance if I had two of the switches directly
connected ( home run ) to the third switch as opposed to running threw each
other.

If yes, could someone point me in the right direction to figure this out.

Thanks

JJ
Anonymous
May 27, 2004 11:21:32 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

"JJ" <Sonbo@comcast.net> wrote:
>I have three switches, they are daisy chained.
>Would I see better performance if I had two of the switches directly
>connected ( home run ) to the third switch as opposed to running threw each
>other.

It depends on the hardware you have attached, the speeds the switches
are running at, and how much traffic you have.

I recently added a gigabit switch to my network, and the two high-end
machines with 1000BT interfaces now get almost 200 megabits when
copying files back and forth, which surprised (and pleased) me.

OTOH, my past upgrade to 10/100 didn't make much difference at all, so
I have evidence on both results.

--
William Smith
ComputerSmiths Consulting, Inc. www.compusmiths.com
Anonymous
May 27, 2004 3:04:12 PM

Archived from groups: comp.dcom.lans.ethernet (More info?)

JJ wrote:

> I have three switches, they are daisy chained.
> Would I see better performance if I had two of the switches directly
> connected ( home run ) to the third switch as opposed to running threw each
> other.
>
> If yes, could someone point me in the right direction to figure this out.
>
> Thanks
>
> JJ
>
>
generally, it's best to put the two switches both connected to the
third, and have all servers plugged into the third as well. Any switch
will give SOME latency (although usual so small as to be pretty much
unmeasurable from the workstation)

--
Copyright 2004 T. Sean Weintz
This post may be copied freely without
the express permission of T. Sean Weintz.
T. Sean Weintz could care less.
T. Sean Weintz is in no way responsible for
the accuracy of any information contained in
any usenet postings claiming to be from
T. Sean Weintz. Users reading postings from
T. Sean Weintz do so at their own risk.
T. Sean Weintz will in no way be liable for
premature hair loss, divorce, insanity,
world hunger, or any other adverse relults
that may arise from reading any usenet
posting attributed to T. Sean Weintz
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Anonymous
May 28, 2004 1:11:30 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

"T. Sean Weintz" <sean@snerts-r-us.org> wrote in message
news:10bc0rcb7rm197d@corp.supernews.com...
> JJ wrote:
>
> > I have three switches, they are daisy chained.
> > Would I see better performance if I had two of the switches directly
> > connected ( home run ) to the third switch as opposed to running threw
each
> > other.
> >
> > If yes, could someone point me in the right direction to figure this
out.
> >
> > Thanks
> >
> > JJ
> >
> >
> generally, it's best to put the two switches both connected to the
> third, and have all servers plugged into the third as well. Any switch
> will give SOME latency (although usual so small as to be pretty much
> unmeasurable from the workstation)

i suggest the main reason for this is to do with system bandwidth.

Your recommended layout has 1 switch as a star point for other switches and
servers. This gives the highest overall system bandwidth (as long as the
backplane within the switch is faster than the switch to switch links -
which should be true by an order of magnitude or more for any reasonable
modern hardware).
>
> --
> Copyright 2004 T. Sean Weintz
> This post may be copied freely without
> the express permission of T. Sean Weintz.
> T. Sean Weintz could care less.
> T. Sean Weintz is in no way responsible for
> the accuracy of any information contained in
> any usenet postings claiming to be from
> T. Sean Weintz. Users reading postings from
> T. Sean Weintz do so at their own risk.
> T. Sean Weintz will in no way be liable for
> premature hair loss, divorce, insanity,
> world hunger, or any other adverse relults
> that may arise from reading any usenet
> posting attributed to T. Sean Weintz
--
Regards

Stephen Hope - return address needs fewer xxs
Anonymous
June 14, 2004 2:49:46 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

"JJ" <Sonbo@comcast.net> wrote in message
news:2hlv2jFef99nU1@uni-berlin.de...
> I have three switches, they are daisy chained.
> Would I see better performance if I had two of the switches directly
> connected ( home run ) to the third switch as opposed to running threw
each
> other.
>
> If yes, could someone point me in the right direction to figure this out.
>
> Thanks
>
> JJ
>
>
Better but not significant the middle switch will add about 7 microseconds
(wirelink+switch latency).
Anonymous
June 15, 2004 7:09:36 AM

Archived from groups: comp.dcom.lans.ethernet (More info?)

"JJ" <Sonbo@comcast.net> wrote in message
news:2hlv2jFef99nU1@uni-berlin.de...

>I have three switches, they are daisy chained.
>Would I see better performance if I had two of the switches directly
>connected ( home run ) to the third switch as opposed to running
> threw each other.

Note that three switches can only go together one way,
unless you specifically identify one.

If you have four than you can have a daisy chain, or one switch
connected to three others.

Now, if you have one server and many clients, then the switch
connected to the server could be considered special, but even
in that case the performance is limited by the link to
the server, anyway.

The topology of switches is similar to carbon atoms
in hydrocarbon compounds in organic chemistry. There
is one way to connect three carbon atoms, but two ways
to connect four.

-- glen
!