dummynet dropping too many packets

[Julian Elischer]

rihad wrote:
> Eugene Grosbein wrote:
>> On Mon, Oct 05, 2009 at 04:50:10PM +0500, rihad wrote:
>>
>>>>> Where has TCP slow-start gone? My router box isn't some application 
>>>>> proxy that starts downloading at full 100 mbit/s thus quickly 
>>>>> filling client's 1 mbit/s link. It's just a router.
>>>> While there is no or little competition for bandwidth from the router
>>>> to clients, TCP would work just fine. I suspect your shaping policy
>>>> makes heavy competition between clients. In this case, TCP behaves
>>>> not-so-well without help of router's good shaping algorythms
>>>> and taildrop is not good one.
>>>>
>>> Nothing fancy (i.e. no competition). Only tons of per-user pipes 
>>> simulating the given throughput.
>>
>> You've mentioned previously: "The pipes are fine, each normally having
>> 100-120 concurrent consumers (i.e. active users)."
>> This IS competition between TCP flows inside each pipe.
>>
> Well, each user gets instantiated with a new copy of the pipe. Each such 
> user counts towards the limit imposed by hash_size*max_chain_len for 
> that pipe only. It would have been competition had I used dst-ip dst-ip 
> 0xffffff00 or similar and not dst-ip 0xffffffff, _then_ all 256 users 
> (determined by the mask) would compete for the pipe's bandwidth. So the 
> only competition is in the uplink at our main Cisco, I guess.

yesssss, so try running your  interfaces slower. :-)

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