I'm good with how to calculate BW from the QoS SRND, however it seems to get a little squishy when it comes to values for cRTP and rounding the output. For example, say I have a requirement to allow 5 g729 calls and I'm using MLP with header compression. We know that by default CRTp should be 2 without checksum and 4 with checksum but in going through the Vol1 and Vol 2 labs and VoDs I've seen both values used with no metion of whether or not checksum was a requirement. So if we calcualte first with cRTP of 2 bytes we get 13 + 2 + 20 = 35 * 8 * 50 = 14000 = *14kbps* .... with cRTP of 4 we get 13 + 4 + 20 = 14800 = *14.8kbps.* Now if we multiply this out by the number of calls we get 14kbps * 5 = *70kbps* and 14.8 * 5 = *74kbps *respectively .... or do we? Because I've seen the rounding take place earlier on so we would in essence have 15kbps * 5 = *75kbps.*
Keep in mind this is if your following the SRND. Vik and Amy recommend using 9bytes as the L2 value for MLP as opposed to 13bytes... I realize this is a more accurate number but do we have any official guidance as to how the proctors are grading this? Are they using values strictly from the SRND? How big is the window or margin of error for these calculations? I know this sounds like splitting hairs but I've taken the lab before and walked away with 0 points in QoS not knowing why. Thanks in advance for any insight? KP
_______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com
