ipfw pipes: theoretical speed vs. reality

[Justin Bennett]

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|
|
| Justin Bennett wrote:
|
| All,
|
| I have recently been setting up pipes to shape bandwidth on our local
| net.
|
| However, unless I am missing something, the TCP overhead seems quite
| large.
|
| If I configure the following pipe:
|
| $IPFW pipe 1 config bw 64Kbit/s
| $IPFW add 31 pipe 1 ip from 192.168.0.1/24 to any
| $IPFW add 32 pipe 1 ip from any to 192.168.0.1/24
|
| The run traffic from my machine (192.168.0.2) through it, I get less
| than half the expected bandwidth (3.9KB/s). I tried another test with a
| 512Kbit/s pipe, and got around 30KB/s.
|
| I know on most ATM/FR lines, you can expect about 10% overhead, but 50%
| seems high.
|
| When I remove the pipe, my T1 comes back to life, and I can pull the
| same data at 160+KB/s.
|
| Am I missing something?
|
|
|
|> yes you are queuing data in both directions on the same queue, thus
|> serialising it..
|
|> use 2 seprarate pipes. one for each direction.

Thanks. I knew it was simple, just couldn't wrap my head around it.
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