[149078] in North American Network Operators' Group
Re: 10GE TOR port buffers (was Re: 10G switch recommendaton)
daemon@ATHENA.MIT.EDU (Nick Hilliard)
Fri Jan 27 19:52:14 2012
X-Envelope-To: nanog@nanog.org
In-Reply-To: <CAEs2ZiJb4SXWnw0JfeU+ZemQRkW3JtMntb72v2usT-R1S_D1Xg@mail.gmail.com>
From: Nick Hilliard <nick@foobar.org>
Date: Sat, 28 Jan 2012 00:51:20 +0000
To: bas <kilobit@gmail.com>
Cc: nanog <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On 27 Jan 2012, at 23:08, bas <kilobit@gmail.com> wrote:
> Im my (our) busines model _is_ the internet connectivity...
> We could give the customer double the port capacity, if they were
> willing to pay, but in real life they do not care...
>=20
> While all respondents replies hold truth a (technial business) logic.
> None shed a light why there isn't TOR box that does 10GE deepbuffers
There are a couple of reasons for this: first, dropping the amount of buffer=
space decreases the cost of the hardware. Secondly, you really only need l=
arge buffers when you need to shape traffic. Shaping traffic is important i=
f you're down stepping from a faster port to a slower port (this is a common=
use case for a blade switch like a c6500), or else if you're running qos on=
the port and you need to implement sophisticated queuing and policing. You=
can't run qos effectively without having generous buffers which is why LAN s=
witches typically have very little buffer space and metro Ethernet switches t=
ypically have lots.
In the case of a tor switch, the use case is typically in a situation where y=
ou're not downstepping from a higher speed to a lower speed, and where you d=
on't really need fancy qos. So as its not generally needed for the sort of t=
hings that tor switches are used for, its not added to the hardware spec.=20=
Nick=20=
