[112343] in North American Network Operators' Group
Re: switch speed question
daemon@ATHENA.MIT.EDU (Roy)
Tue Feb 24 12:15:38 2009
Date: Tue, 24 Feb 2009 09:15:24 -0800
From: Roy <r.engehausen@gmail.com>
CC: NANOG list <nanog@nanog.org>
In-Reply-To: <5792267e0902240751w2021e473k33f02acd5acb4304@mail.gmail.com>
Errors-To: nanog-bounces@nanog.org
Eric Gearhart wrote:
> ....
>
> Note that the traffic to a switch is bi-directional (full duplex) - so
> a 24 port gigabit switch can max out its 32 Gig backplane, if all 24
> ports have a gig coming in and going out (24 X 2 is 48, more than the
> 32 gig backplane).
>
> ....
>
I think your math is faulty. While there may be 24G going in and 24G
going out, there is only 24G crossing the backplane. You can't count a
bit twice (once on in and once on out). Its the same bit.
