[lug] networking question

[Sean Reifschneider]

On Thu, Jan 22, 2004 at 01:02:27AM -0500, Hugh Brown wrote:
>Is there any throughput advantage to connecting two switches with two
>ethernet cables as opposed to one?

Yes, there can be some including better resiliancy and additional
bandwidth.

>switches upstairs (essentially we are forming a backbone).  The switches
>are unmanaged.  I assume it is a good idea to have a second cable for
>redundancy, I'm just curious to know if the throughput goes up.

If the switches are unmanaged, you are probably entering a world of
pain.  A WORLD OF PAIN.  The switches are probably just going to
saturate those two ports looping traffic between them.

If your switches support "Spanning Tree Protocol", which most managed
switches support, you should be able to just connect the two switches
with 2 cables and the switches will use the lowest numbered port (in STP
sense, not the "lables on the front" sense) to send data.  If that
connection dies, it should switch over to the other port automatically.

If your switches support "trunking", which most managed switches do, you
can use multiple connections between switches (when the ports are
configured as trunking ports), and the switch will use those ports to
provide N times the bandwidth of a single port.  If one port dies for
whatever reason, the switches will still remain connected, just at a
lower rate.

Both switches have to support these features for you to be able to do
it.

Trunking or gigabit uplink ports will be important if you want more than
one person upstairs to be able to communicate with more than one person
downstairs at full bandwidth.

Sean
-- 
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Sean Reifschneider, Member of Technical Staff <jafo at tummy.com>
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