[36968] in North American Network Operators' Group
Re: jumbo frames
daemon@ATHENA.MIT.EDU (Greg Maxwell)
Fri Apr 27 12:11:41 2001
Date: Fri, 27 Apr 2001 11:45:04 -0400 (EDT)
From: Greg Maxwell <gmaxwell@martin.fl.us>
To: Kurt Kayser <kurt@noris.de>
Cc: Tony Hain <alh-ietf@tndh.net>, Roeland Meyer <rmeyer@mhsc.com>,
John Fraizer <nanog@Overkill.EnterZone.Net>,
Paul Lantinga <prl@q9.com>, nanog@merit.edu
In-Reply-To: <20010427170658.X11588@noris.de>
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Errors-To: owner-nanog-outgoing@merit.edu
On Fri, 27 Apr 2001, Kurt Kayser wrote:
> Hi,
>
> Isn't it a lot more cpu-intensive to 'collect' some 1500-byte frames
> into some larger bucket, reassemble it into a jumbo-frame when the next
> box has to chop it in order to send it out on a Sonet/PPP/etc interface which
> might have a smaller MTU again?
>
> Doesn't make too much sense to me. I guess that was Tony's aim as well..
>
> Kurt
>
> > Roeland you are talking about jumbo frames from the end system lan, while
> > John is talking about only using the jumbo frames between the routers. My
> > point was that in John's environment the packets will all be 1500 since the
> > packets are restricted to that size just to get to the router with the GE
> > interface. I understand that there are perf gains as long as the entire path
> > supports the larger packets, but I don't understand the claim that having a
> > bigger pipe in the middle helps.
I dont think that anyone discussed doing that... What was being said was
that it makes sence to use jumbo frames between routers when they are
encapsulating packets from links with a 1500b mtu, so you don't have to
reduce your MTU to 1450 or fragment, i.e.
endnode-ether-router>tunnel-jumbo_ether-router-jumbo-ether-tunnel>router-eth-end
