It was my understanding that (most) cable modems are L2 devices -- how it is that they have a buffer, other than what the network processor needs to switch it? Frank -----Original Message----- From: Leo Bicknell [mailto:bicknell@ufp.org] Sent: Monday, March 16, 2009 9:10 AM To: nanog@nanog.org Subject: Re: Shady areas of TCP window autotuning? <snip> What appears to happen is vendors don't auto-size queues. Something like a cable or DSL modem may be designed for a maximum speed of 10Mbps, and the vendor sizes the queue appropriately. The service provider then deploys the device at 2.5Mbps, which means roughly (as it can be more complex) the queue should be 1/4th the size. However the software doesn't auto-size the buffer to the link speed, and the operator doesn't adjust the buffer size in their config. <snip> My wish is for the vendors to step up. I would love to be able to configure my router/cable modem/dsl box with "queue-size 50ms" and have it compute, for the current link speed, 50ms of buffer. Sure, I can do that by hand and turn it into "queue 20 packets", but that is very manual and must be done for every different link speed (at least, at slower speeds). Operators don't adjust because it is too much work. <snip> -- Leo Bicknell - bicknell@ufp.org - CCIE 3440 PGP keys at http://www.ufp.org/~bicknell/