cbt-1

Question

A Selective Repeat ARQ is using 7 bits to represent the sequence numbers.The maximum window size is __________.

(ans is 64)

why It is  

Answer 1

because in SR protocol both sender window size and receiver window size must be equal.

• Sender’s Windows ( Ws) = Receiver’s Windows ( Wr).
• so maximum window size possible in SR =$2^n/2$  =    
• but in GBN sender window =n  and receiver window always 1 
• so in Maximum sequence number possible in GBN= $2^n-1$