Re: [ssm] Multicast SSM throughput in 802.11

[Tiago Sousa <tmas@dei.uc.pt>]

Hello to all.

Thanks for the reply. I extend the gratefulness to the others that had
answered.=20

My wireless access point is configured to send traffic at rate of 54Mbps
(802.11g) although my mobile node receives at 11Mbps (802.11b). So, if i
understand well your suggestion the Basic Rate settings are well
implemented because it is only specified 54Mbps in the AP. Am i correct?

I didn't understand the suggestion of Gaurav: Profiled TCP. Can you
explain better? The multicast throughput (UDP based) can also depends of
the TCP profile?=20

The suggestion of Matthias: check in the AP if the multicast rate is
limited. I've been in the web-based interface and i didn't find any item
that refer to multicast. I am using a Belkin 54g AP.

My opinion is that the problem must be in the AP because the outgoing
interface of the access router sends traffic at 4 Mbps. The only thing
in the middle, between the router and the MN, is the AP. So, the
throughput must be affected by some item in the AP.=20
I've confirmed all the possible items in the AP and i didn't find any
related with multicast...  =20

Do you have more suggestions?

Thanks to all.


Tiago Sousa

Qui, 2005-10-20 =C3=A0s 11:00 -0400, Peter Gutierrez escreveu:
> tmas@dei.uc.pt wrote:
> > I am testing the PIM-SSM daemon (both freebsd and linux) and mrd6
> > program in a wireless link.=20
> >=20
> > The problem I encountered, with both pim6sd daemon and mrd6, is that
> > I'm sending multicast traffic at 4 Mbps and the throughput reaches th=
e
> > mobile node (which is very near from de access point) rounding 40
> > kbps.
> >=20
> > I am using the mad-flute tool to send the multicast SSM traffic and
> > the tcpdump plus trpr to analyze the data.
> >=20
> > =20
> >=20
> > Anyone knows why the throughput decreases so much in the wireless
> > link?=20
> >=20
> > =20
> >=20
> > I would appreciate any help/hint that helps me to explain these
> > results.=20
>=20
> Although it should not have the effect of limiting traffic to 40kbps,=20
> don't forget that multicast frames must be transmitted at a rate that=20
> is included in the Basic rate set according to the IEEE 802.11=20
> specification. The basic rate set usually includes 1Mbps, not the=20
> 11Mbps or even 54Mbps (in 802.11g radios) that your client may claim to=
=20
> be its rate (which it is for unicast traffic).
>=20
> You may want to try removing the lower rates from the Basic set on the=20
> access point, to see if your throughput increases, if this is in a test=
=20
> environment. If a client does not support the Basic rate, it will not=20
> associate.
>=20


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