Re: [ssm] Multicast SSM throughput in 802.11

[Peter Gutierrez <peterg@nic.umass.edu>]

tmas@dei.uc.pt wrote:
> 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? 
> 
> 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.  I've confirmed
> all the possible items in the AP and i didn't find any related with
> multicast...   
> 
> Do you have more suggestions? 

I am not familiar with a Belkin AP, so I can only suggest you determine 
what rates are set as Basic. I can't suggest how you do so.

The access points I use have ssh capabilities, and I can login and 
query about the state of the AP, e.g.,

AP> show controller dot11Radio 0
!
[snip]
Current Rates:  2.0 basic-5.5 6.0 9.0 11.0 12.0 18.0 24.0 36.0 48.0 54.0
Active Rates:  2.0 basic-5.5 6.0 9.0 11.0 12.0 18.0 24.0 36.0 48.0 54.0
Allowed Rates:  1.0 2.0 5.5 6.0 9.0 11.0 12.0 18.0 24.0 36.0 48.0 54.0
Best Range Rates:  basic-1.0 2.0 5.5 6.0 9.0 11.0 12.0 18.0 24.0 36.0 
48.0 54.0
Best Throughput Rates:  basic-1.0 basic-2.0 basic-5.5 basic-6.0 
basic-9.0 basic-11.0 basic-12.0 basic-18.0 basic-24.0 basic-36.0 
basic-48.0 basic-54.0
Default Rates:  basic-1.0 basic-2.0 basic-5.5 6.0 9.0 basic-11.0 12.0 
18.0 24.0 36.0 48.0 54.0


Note that all multicast (and broadcast and control) frames would be 
transmitted at 2.0Mbps on this AP.

Perhaps there is a screen output from the Belkin that displays the 
enabled rates and specifies which are Basic.


Also, you may have better results asking your questions on a different 
list, instead of this ssm specific IETF list. I suggest the Internet2 
multicast working group list, <mailto:sympa@internet2.edu?subject=help> 
since you appear to be from an institution that routes to Internet2.

-- 
Peter Gutierrez  OIT/Network Services  U. Massachusetts Amherst
Voice: 413 545 1606   Fax: 413 545 3203    peterg@nic.umass.edu
Opinions?  "Ain't nobody's business but my own" - Irving Taylor


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