Duplicate pings again (traffic control answer).

Simon Waters Simon at wretched.demon.co.uk
Fri Dec 13 00:49:51 EST 2002


Okay;

hostap_plx with Linksys card, STA 1.4.9 9 evil firmware ;-),
WISP (see leaf.sourceforge.net).

Clients, both using Lucent Silver Cards
	2.2.19 Linux + wvlan_cs.o (from pcmcia_cs3.2.0 I think)
	Mandrake 8.1 + orinoco.o

Both pinging hostap default ping options, no duplicates.

Both pinging each other, via hostap, lots and lots of duplicates
(nearly 1 per packet).

One pinging access point default settings, one using larger
packet size (-s 6550), odd duplicate packet spotted.

Pinging AP, ping size pumped up to maximum allowed on one client
- oh dear - one doesn't return, the other coughs duplicates-
should I have enabled fragmenting?

Simply switching of retires "iwconfig wlan0 retry 0" on
hostap_plx access point, gave three or four duplicates per
packet.

I'm missing something simple (or basic) here I fear.

All tests done with enc 0102-0304-00, although unencrypted I
still got duplicates, I didn't test much further of unenc.

 Simon

PS: To answer an earlier question of mine, traffic control seems
to work on packets going through access point (via same master
hostap_plx card, and same subnet), at least in some fashion.
i.e. I can restrict my throughput down to a few Kbytes, and use
various smart queuing on ingress and egress to give a better
balance between sessions (although I think the hashing
algorithmn had some trouble distinguishing two SSH sessions
between the same two hosts). Too soon to say if there is a
downside, but I don't seem off hand why it should be different
to cabled traffic shaping. Although till I get better throughput
and less duplicates it is hard to be confident in the subtler
effects.



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