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[altq:1888] Re: CBQ: small pakets are too limited !
Right, altq works at device driver's level and the "exactbandwidth"
parameter includes the Ethernet header (as far as I understood and
verified). The throughput measured by altqstat also includes the
Ethernet header.
This throughput corresponds very well to the throughput given by
'netstat -I xl0 -w 1' which also includes the ethernet header.
Then my feeling is that I should really get 2.4Mbps, as specified in the
conf file, and not 1.7Mbps. For the experiment, the incoming traffic is
about 3Mbps (including ethernet) when the packet size is 50 bytes (UDP).
Thanks,
Emmanuel
On Tue, 2003-08-19 at 17:11, Luigi Rizzo wrote:
> if i remember well, altq works at the device driver's level
> so it probably uses the MAC frame size instead of the IP size.
> The extra 18 bytes (possibly together with a min frame size
> of 64 bytes) might explain the difference.
> cheers
> luigi
>
> On Tue, Aug 19, 2003 at 04:41:24PM +0200, Emmanuel Duros wrote:
> > Hi,
> >
> > I have a router based on FreeBSD 4.4R with altq-3.0.
> >
> > My router is dedicated to route udp traffic that is shaped with altq. My
> > problem is that I have not been able to shape correctly udp traffic
> > composed of small packets (e.g. 50 to 500 byte-long). The outgoing
> > traffic is significantly below the bandwidth set in altq.conf.
> >
> > However, when I increase the packet size, I can reach the correct
> > bandwidth.
> >
> > Here is my setup:
> >
> > Traffic fxp0 ALTQ xl0
> > generator ------------ router -------------
> > (UDP)
> >
> > Altq conf file is:
> >
> > interface xl0 bandwidth 10000000 cbq
> > class cbq xl0 root_class NULL pbandwidth 100
> > class cbq xl0 def_class root_class pbandwidth 100 default
> > class cbq xl0 udp_class def_class exactbandwidth 2400
> > filter xl0 udp_class 0 0 0 0 17
> >
> > With this configuration I would expect to see a 2.4Mbps outgoing
> > traffic.
> > However when genrating UDP packet of 50 bytes at 2.5Mbps, at the routeur
> > the outgoing throughput is about 1.7Mbps ! altqstat gives the following
> > output:
> > Class 0 on Interface xl0: udp_class
> > priority: 1 depth: 0 offtime: 7720 [us] wrr_allot: 590 bytes
> > nsPerByte: 3333 (2.40M Mbps), Measured: 1.76M [Mbps]
> > pkts: 1418941, bytes: 137803622
> > overs: 49551, overactions: 48920
> > borrows: 0, delays: 48920
> > drops: 96679604, drop_bytes: 96679604
> > QCount: 1, (qmax: 30)
> > AvgIdle: -5 [us], (maxidle: 2512 minidle: -4999 [us])
> >
> > When I increase the size of UDP pkt up to 1000 bytes, then I can reache
> > 2.4Mbps.
> >
> > How can I get the 2.4Mbps as I would expect for UDP traffic made of
> > small packets as well as "large" packets ????
> >
> > Thanks
> > Emmanuel Duros
> >
> > --
> > Emmanuel Duros http://www.udcast.com
> > 2455 Route des Dolines BP355 | Tel : +33 (0)4 93 00 16 60
> > 06906 Sophia Antipolis France | Fax : +33 (0)4 93 00 16 61
> > ** Full IP over Broadcast Media **
--
Emmanuel Duros http://www.udcast.com
2455 Route des Dolines BP355 | Tel : +33 (0)4 93 00 16 60
06906 Sophia Antipolis France | Fax : +33 (0)4 93 00 16 61
** Full IP over Broadcast Media **