On Tue, Dec 11, 2007 at 12:31:00PM +0400, rihad wrote: >Peter Jeremy wrote: >> On Tue, Dec 11, 2007 at 09:21:17AM +0400, rihad wrote: >>> And if I _only_ want to shape IP traffic to given speed, without >>> prioritizing anything, do I still need queues? This was the whole point. >> No you don't. I'm using pipes without queues extensively to simulate >> WANs without bothering with any prioritisation. > >Great! One fine point remains, though: ># ipfw pipe 1 config bw 128Kbit/s >will use a queue of 50 slots by default. What good are they for, if I >didn't ask for queuing in the first place?
'queue' is used in two distinct ways within the ipfw/dummynet code: 1) There's a "queue" object created with 'ipfw queue NNN config ...' This is used to support WF2Q+ to allow a fixed bandwidth to be unevenly shared between different traffic types. 2) There is a "queue" option on the "pipe" object that defines a FIFO associated with the pipe. I had assumed you were talking about the former (and my response was related to this) but given your latest posting, and having re-read the thread, I suspect I may have been wrong. Whilst I don't use queue objects, I do use the queue option on my pipes. In your example, you have a pipe that can handle 128kbps (16kBps). If you write a 1600byte packet to it, then the packet will reappear 100msec later. Any further packets written to that pipe during that time will be dropped if they can't be placed on a queue. The practical throughput depends on the number of queue slots available and the number of writers. I suggest you do some reading on queueing theory for the gory details. -- Peter Jeremy Please excuse any delays as the result of my ISP's inability to implement an MTA that is either RFC2821-compliant or matches their claimed behaviour.
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