[altq 690] Re: How to configure altq as a RED router

[Kenjiro Cho <kjc@csl.sony.co.jp>]

Tatsuhiko Terai wrote:
> I'd like to use ALTQ as below.
> 
> +-------+          +----------------+           +---------+
> +Server +----------+RED router(ALTQ)+-----------+Client   + 
> +-------+1000Base  +-------+--------+1000Base   +---------+
>    (ti0)          (ti0)           (ti1)        (ti0)   
> 192.168.0.1    192.168.0.2         192.168.1.2    192.168.1.1       
>                            
> 
> Router machine have two Tigon Gigabit Ethernet card and 100Base
> Ethernet card.
> 
> I'm trying to use RED router, since I want the "Packet loss 
> (dropping) case" to set RED router between server and client.

The queue size at the router won't grow in this setting since the
input rate can't exceed the output link rate.

> Without ALTQ working, the result of TCP throughput using netperf is
> below
>       Sender and Receiver's buffer size : 1048576 byte
>       Server -- router : 630 Mbps
>       Server -- router -- Client : 350 Mbps
> 
> I think this decrease of throughput is because of PC router overhead
> (Is it right? I wonder)

Or, it could be that the TCP window size is too small to absorb the
increase in RTT.

> When configuring ALTQ as a RED router above network topology,
> May I simply write to /etc/rc.conf below ? (without consindering 
> RED tuning parameter (min_th, max_th or so)
>   interface ti0 bandwidth 1000M red
>   interface ti1 bandwidth 1000M red

Yes.

> And how can I know the default RED parameter ?

Run altqstat.

-Kenjiro