[quagga-users 12565] Re: bgp - quagga-0.99.18

Alexis Rosen quagga-users at alexis.users.panix.com
Fri Nov 11 08:37:05 GMT 2011


On Nov 8, 2011, at 12:57 PM, Ingo Flaschberger wrote:
>        +--------------------+
> input ->|    1 mbit queue    |-> output
>        +--------------------+
>                            ^
>                            |
>                         small packet input
> [...]

There's rather more to the problem than what you do with small packets. And if you think that "the queue" is just 1mbit, you're mistaken - just at the level of one ethernet port's ring buffers, you could choose to configure 4096*9000 bytes of buffering. That alone could produce ~300ms of buffering on a gigabit interface. (Yes, that's generally unrealistic, but 4k*1500 bytes is not, and that still amounts to 50ms.) And that doesn't take into account the various other layers of buffering you may have in your system. Stick ten or twenty routers in between source and destination and you could have a real problem, if enough people make the wrong choices.

/a


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