[29344] in North American Network Operators' Group
Re: Jumbo Frames (was Re: MAE-EAST Moving? from Tysons corner to
daemon@ATHENA.MIT.EDU (michael.dillon@gtsip.net)
Mon Jun 19 05:19:20 2000
Date: 19 Jun 2000 10:18:09 +0100
Message-ID: <20000619091809.20843.cpmta@c000.lhr.cp.net>
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To: nanog@merit.edu
From: michael.dillon@gtsip.net
Errors-To: owner-nanog-outgoing@merit.edu
On Mon, 19 June 2000, "Bora Akyol" wrote:
> As long as most end users are running Ethernet, Fast Ethernet, DSL or Cable
> Modems, what is the point of jumbo frames/packets other than transferring
> BGP tables really fast. Did any one look into how many packets are moved
> through an OC-48 in 1 seconds. (approx. 6 million 40 byte packets). I think
> even without jumbo frames, this bandwidth will saturate most CPUs.
>
> Jumbo frames are pointless until most of the Internet end users switch to a
> jumbo frame based media.
>
> Yes, they look cool on the feature list (we support it as well). Yes they
> are marginally more efficient than 1500 byte MTUs ( 40/1500 vs 40/9000). But
> in reality, 99% or more of the traffic out there is less than 1500 bytes. In
> terms of packet counts, last time I looked at one, 50% of the packets were
> around 40 byte packets (ACKs) with another 40% or so at approx 576 bytes or
> so.
>
> What is the big, clear advantage of supporting jumbo frames?
When 1500 byte frames from the customer's LAN enter the customer's router and enter some form of IP tunnel, then a core fabric which supports larger than 1500 byte frames will not cause fragmentation. It's not necessary to do the full jumbo size frames. I suspect that supporting two levels of encapsulation will be enough in 99.9% of the cases. For the sake of argument, what would be the downside of using a 2000 byte MTU as the minimum MTU in your core?
---
Michael Dillon Phone: +44 (20) 7769 8489
Mobile: +44 (79) 7099 2658
Director of Product Engineering, GTS IP Services
151 Shaftesbury Ave.
London WC2H 8AL
UK
