Development issues regarding the cerowrt test router project
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From: Michael Richardson <mcr@sandelman.ca>
To: dpreed@reed.com
Cc: cerowrt-users@lists.bufferbloat.net, cerowrt-devel@lists.bufferbloat.net
Subject: Re: [Cerowrt-devel] [Cerowrt-users] QOS settings vs speedboost and random bandwidth
Date: Mon, 26 Nov 2012 10:38:33 -0500	[thread overview]
Message-ID: <13866.1353944313@obiwan.sandelman.ca> (raw)
In-Reply-To: <1353942251.571510886@apps.rackspace.com>

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>>>>> "dpreed" == dpreed  <dpreed@reed.com> writes:
    dpreed> You can use a small fraction of the capacity of the cable
    dpreed> uplink path to measure its queueing delay dynamically, and
    dpreed> when it gets longer than latency*"expected bitrate", reduce
    dpreed> "expected bitrate". 
 
    dpreed> You want to do this *as quickly as possible*, so what you do
    dpreed> is insert a "link monitor" task in the driver that sends
    dpreed> tiny probe packets addressed to the nearest "loopback point"
    dpreed> you can find/create on the other side, and measure the RTT.
    dpreed> You can use, for example, the technique used by traceroute,
    dpreed> which is to set the hop count to the smallest number that
    dpreed> causes a return ICMP packet to be sent, and send one of
    dpreed> those periodically. 

As I understand it, you can do this with 802.1ag
  http://en.wikipedia.org/wiki/IEEE_802.1ag, 
with the Loop-back frames as well.

Whether or not any of this is enabled on typical broadband networks, I
have no idea.

    dpreed> I used this specific technique to cause my uplink queue to
    dpreed> move back into my router, where I could manage it.  You can
    dpreed> also use it for the downlink queue measurement, but it
    dpreed> doesn't move the queue into the router smoothly, instead you
    dpreed> have to drop/ECN-mark the IP frames coming in. 

    dpreed> This can all be done between the IP layer and layer 2.
    dpreed> Since it exploits speedboost better, it might be worth
    dpreed> adding as an option to cerowrt, so you don't have to set a
    dpreed> speed limit explicitly when you have a single connection to
    dpreed> the public Internet. 

wow, this would be awesome... code??
-- 
]       He who is tired of Weird Al is tired of life!           |  firewalls  [
]   Michael Richardson, Sandelman Software Works, Ottawa, ON    |net architect[
] mcr@sandelman.ottawa.on.ca http://www.sandelman.ottawa.on.ca/ |device driver[
   Kyoto Plus: watch the video <http://www.youtube.com/watch?v=kzx1ycLXQSE>
	               then sign the petition. 


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  reply	other threads:[~2012-11-26 15:38 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20121125232034.GF24680@merlins.org>
2012-11-26  8:32 ` Dave Taht
2012-11-26 14:22   ` Michael Richardson
2012-11-26 15:04     ` dpreed
2012-11-26 15:38       ` Michael Richardson [this message]
2012-11-26 16:37         ` dpreed
2012-11-26 18:11           ` Michael Richardson
2012-11-26 19:23             ` Marc MERLIN
2012-11-26 19:58             ` dpreed
2012-11-26 21:27               ` Michael Richardson
2012-11-26 22:26                 ` dpreed
2012-11-26 15:35     ` Jim Gettys
2012-11-26 18:13       ` Michael Richardson
2012-11-26 18:28         ` Jim Gettys
2012-11-26 21:29           ` Michael Richardson
2012-11-26 15:27   ` Jim Gettys

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