On 31 August 2016 at 16:51, James Bensley <[email protected]> wrote:
Hey, > Even if it does have a correct (large enough) burst size set, when you > trying to police in the range of Gbps on these cards, you might be > hitting the max burst limit. For LAN cards its around 31250000 bytes > (circa 250Mbits per second). Consider 3Gbps * 300ms = 112.5MB, so your TCP window needs to grow to 112.5MB to get 3Gbps rate on 300ms latency. TCP windows grow exponentially, so worst case window growth could be ~56MB, sender could be 100Gbps for all we know, so we could be looking at this 56MB bursting all at once. If you can't send it through policer, window fails to grow, and full 3Gbps can't be done on single TCP session. On the flip side if you do allow 56MB bursts at linerate, that'll not give you very good QoS, and you might end up congesting some buffers along the way, so it's going to be compromise any way you look at it. I would recommend OP configures shaping instead. -- ++ytti _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
