In a message written on Tue, Feb 03, 2004 at 08:15:13AM -0600, Terry Baranski wrote:
The performance gain achieved by using jumbo frames outside of very specific LAN scenarios is highly questionable, and they're still not standardized. Are "jumbo" Internet MTUs seen as a pressing issue by ISPs and vendors these days?
While the rate of request is still very low, I would say we get more and more requests for jumbo frames everyday. The pressing application today is "larger" frames; that is don't think two hosts talking 9000 MTU frames to each other, but rather think IPSec or other tunneling boxes talking 1600 byte packets to each other so they don't have to split 1500 byte Ethernet packets in half. Since most POS is 4470, adding a jumbo frame GigE edge makes this application work much more efficiently, even if it doesn't enable jumbo (9k) frames end to end. The interesting thing here is it means there absolutely is a PMTU issue, a 9K edge with a 4470 core. There is also a lot of work going on in academic networks that uses jumbo frames. I suspect in a few more years this will make it into more common applications. In a message written on Tue, Feb 03, 2004 at 04:40:15PM +0200, Petri Helenius wrote:
Me wonders why people ask for 40 byte packets at linerate if the mtu is supposedly larger?
This is a problem that is going to get worse. I support IP you have to support a 40 byte packet. As long as that exists, DDOS tools will use 40 byte packets, knowing more lookups are harder on the software/hardware in routers. At the same time I suspect software is going to continue to slowly move to larger and larger packets, because at the higher data rates (eg 40 gige) it makes a huge difference in host usage. You can fit 6 times in the data in a 9K packet that you can in a 1500 byte packet, which means 1/6th the interrupts, DMA transfers, ACL checks, etc, etc, etc. -- Leo Bicknell - bicknell@ufp.org - CCIE 3440 PGP keys at http://www.ufp.org/~bicknell/ Read TMBG List - tmbg-list-request@tmbg.org, www.tmbg.org