Layer 2 header issues ; voice call bandwidth calculation
Hai Mark ,
I have been going through your ccie voice advanced technologies .In Qos you have mentioned that frame relay header size in 4 bytes which is true according to srnd .This was a fact that i was not at all able to digest because for the past 4 years according to me it was 6 byte header followed by 3 byte trailer .Why I was asking you this question is because I was following IP Telephony Self Study Qos which is written by Wendell odom .Within this book it is explicitly mentioned in page 477 that frame relay header is 6bytes + 3 byte Trailer. Also within cisco official curriculum books that talked about how to calculate the bandwidth for a voice call ,there also the information for frame relay header is 6 bytes .For ethernet trunk its 22+4=22 bytes ,ppp its 6-9 bytes etc .Things changed when I have seen Qos SRND .
Which document shold i follow ,Qos SRND or cisco official curriculum ?
whats the reason for ambiguity regarding this information ?
Hope to receive an answer from you .
Thanks for your valuable time .