[112341] in North American Network Operators' Group
Re: switch speed question
daemon@ATHENA.MIT.EDU (Tony Varriale)
Tue Feb 24 11:10:33 2009
From: "Tony Varriale" <tvarriale@comcast.net>
To: "NANOG list" <nanog@nanog.org>
Date: Tue, 24 Feb 2009 10:04:36 -0600
Errors-To: nanog-bounces@nanog.org
That isn't always true. Some switches are already speced as full. It's
best to read the product docs or speak with a rep to be sure.
tv
----- Original Message -----
From: "Eric Gearhart" <eric@nixwizard.net>
To: "NANOG list" <nanog@nanog.org>
Sent: Tuesday, February 24, 2009 9:51 AM
Subject: Re: switch speed question
> On Tue, Feb 24, 2009 at 2:33 AM, Bruce Grobler <bruce@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?"
>
> --
> Eric
> http://nixwizard.net
>
