switch speed question

Eric Gearhart eric at nixwizard.net
Tue Feb 24 15:51:12 UTC 2009

On Tue, Feb 24, 2009 at 2:33 AM, Bruce Grobler <bruce at yoafrica.com> wrote:
> Hi,
> It depends on how heavily loaded your switch is expected to be, for instance
> two machines using the switch will be able to get a full 1Gbps, however
> depending on the backplane (switching fabric), it limits how many ports will
> receive full 1Gbps when the switch is congested, e.g. a 2 gig backplane
> against a 24 gig.
> Regards,
> Bruce

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).

This isn't immediately apparent - the other day someone at my work
asked the exact question "Why's the 32 gig backplane > the 24 ports on
the switch?"


More information about the NANOG mailing list