A damp discussion of network queuing
A damp discussion of network queuing
Posted May 16, 2015 17:55 UTC (Sat) by mtaht (subscriber, #11087)In reply to: A damp discussion of network queuing by nix
Parent article: A damp discussion of network queuing
However I must note that your excellent result was probably due to fq_codel taking advantage of hardware flow control exerted by the DSL modem, which then is seen by fq_codel as delay and managed appropriately, where pfifo_fast would just keep buffering until it hits the packet limit.
Most edge devices today do not exert hardware flow control. Certainly I feel that {dsl,cable}modems should use hardware flow control! It is a sane signal that can also be aware of congestion on media. But nearly everybody put switches, rather than ethernet devices in the path here, over the past 5 years, and lost that capability. So we have generally have had to use software rate limiting (sqm-scripts) to succeed here... or to push for more hardware flow control (or smarter modems)
Posted May 19, 2015 19:23 UTC (Tue)
by nix (subscriber, #2304)
[Link] (2 responses)
Thank you for a most excellent qdisc, anyway!
Posted May 19, 2015 19:40 UTC (Tue)
by dlang (guest, #313)
[Link] (1 responses)
they are commonly a system running linux with an ADSL modem and an ethernet connected to a 4-port switch.
Unfortunately they usually are using a binary driver for the DSL side, so getting them supported by OpenWRT is hard :-(
If they were based on the current OpenWRT instead of a several-year-old one, they would be using fw_codel by default.
Posted May 20, 2015 10:15 UTC (Wed)
by paulj (subscriber, #341)
[Link]
A damp discussion of network queuing
I am glad to see the rhine patches finally landed. There were a few popular devices used as firewalls that used that chipset.
Indeed there were (though I don't know if the Soekris net5501 I use could ever be defined as 'popular' except among the geekiest crowd and those who want to network up oil rigs.)
However I must note that your excellent result was probably due to fq_codel taking advantage of hardware flow control exerted by the DSL modem
That's what I presumed. Nothing else could explain how it managed to figure out my ADSL bandwidth given the total absence of any other way to detect it.
But nearly everybody put switches, rather than ethernet devices in the path here, over the past 5 years, and lost that capability.
Yeah. I guess if your modem has only one port, and you don't have a dedicated multi-port firewall box, that's all you can really do... I wonder: are the very common 'four-port ADSL modems' actually an ADSL modem and a switch in the same box? If so, I guess they're eschewing flow control too, right? :(
A damp discussion of network queuing
A damp discussion of network queuing