I don't think it matters that everything can use jumbograms or that every single device on the Internet supports them. Heck, I still know networks with kit that does not support VLSM! What would be good is if when a jumbogram capable path on the Internet exists, jumbograms can be used. This way it does not matter than some box somewhere does not support anything greater than a 1500 byte MTU, anything with such a box in the path will simply not support a jumbogram. How do you find out? Just send a jumbogram across the path and see what happens.. ;-) -- Leigh Porter UK Broadband -----Original Message----- From: owner-nanog@merit.edu on behalf of Valdis.Kletnieks@vt.edu Sent: Fri 4/13/2007 3:36 PM To: Saku Ytti Cc: NANOG list Subject: Re: Thoughts on increasing MTUs on the internet On Fri, 13 Apr 2007 08:22:49 +0300, Saku Ytti said:
On (2007-04-12 20:00 -0700), Stephen Satchell wrote:
From a practical side, the cost of developing, qualifying, and selling new chipsets to handle jumbo packets would jack up the cost of inside equipment. What is the payback? How much money do you save going to jumbo packets?
It's rather hard to find ethernet gear operators could imagine using in peering or core that do not support +9k MTU's.
Note that the number of routers in the "core" is probably vastly outweighted by the number of border and edge routers. There's a *lot* of old eBay routers out there - and until you get a clean path all the way back to the source system, you won't *see* any 9K packets. What's the business case for upgrading an older edge router to support 9K MTU, when the only source of packets coming in is a network of Windows boxes (both servers and end systems in offices) run by somebody who wouldn't believe an Ethernet has anything other than a 1500 MTU if you stapled the spec sheet to their forehead? For that matter, what releases of Windows support setting a 9K MTU? That's probably the *real* uptake limiter.