[146227] in North American Network Operators' Group
Re: mtu question. more should be better, right?
daemon@ATHENA.MIT.EDU (David Newman)
Mon Nov 7 13:41:44 2011
Date: Mon, 07 Nov 2011 10:41:32 -0800
From: David Newman <dnewman@networktest.com>
To: nanog@nanog.org
In-Reply-To: <CAAiP322G=5AoEcu46NPOqOC3-wPoyXP5-dth5_YSTbO_vhAqoQ@mail.gmail.com>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On 11/7/11 8:45 AM, Deric Kwok wrote:
> When I setup the server mtu as 9100. why I have to configure the
> switch mtu 9300 to make it working?
>
> What this extra 200 bytes is for what purpose? ls it standard?
MTUs above 2000 bytes are nonstandard. The most recent Ethernet spec,
802.3-2008, defines a maxBasicFrameSize of 1518 octets and a
maxEnvelopeFrameSize size of 2000 octets to accommodate various encap
mechanisms.
> What is disadvantage of setting our all internal networks (host /
> equipment) mtu more than 1500?
In a single data center at 1-Gbit/s rates or above, probably none,
provided all devices support and use the same MTU. In other scenarios
jumbos can lead to the various problems Iljitsch mentioned.
dn
