2 votes 2 votes “An SR sender’s window base cannot a have lower sequence number than the receiver window base” can some one explain this statement ? Why it is false Computer Networks sliding-window computer-networks zeal-test-series + – Kabir5454 asked Jul 13, 2022 edited Jul 14, 2022 by Kabir5454 Kabir5454 448 views answer comment Share Follow See all 4 Comments See all 4 4 Comments reply Shubham Sharma 2 commented Jul 14, 2022 reply Follow Share I think there is a little grammatical error in the statement. The statement should be “An SR sender’s window base cannot have a lower sequence number than the receiver window base”. Honestly, the statement “An SR sender’s window base cannot have a lower sequence number than the receiver window base” does not make any sense.” Because let’s say we have packets with sequence numbers 0,1,2,3,4 and somehow the packet with sequence number ‘0’ is lost or corrupted, as per the functioning of SR, it will be re-transmitting the packet with sequence number ‘0’, which is a lower sequence number. Or Suppose we have received an ACK for the acknowledged packet, so the thing that happens in SR is that the sender window base is moved forward to the unacknowledged packet with the smallest sequence number. If the window moves and there are untransmitted packets with sequence numbers that now fall within the window, these packets are transmitted. So that’s why the statement is false. If there is any other reason than this, do share. Ref: Selective-Repeat (Page No. 3 -> Figure No. 3 -> Point No. 3) Ref: CN – 6th ed Kurose & Ross (Page no. 225 & 226) 1 votes 1 votes Kabir5454 commented Jul 14, 2022 reply Follow Share @Shubham Sharma 2 What does the base mean here ? is it the index of the smallest packet which is not yet acknowledged ? 0 votes 0 votes Shubham Sharma 2 commented Jul 14, 2022 reply Follow Share Yes, it is sort of an index for the packets within the window which are sent but not ack'd yet and those on the receiver which are expected but not received yet. Moreover, the word 'base' is a terminology picked up by a certain authors. we may find a different term ( like "First outstanding") if we refer to some other standard textbook. 0 votes 0 votes Kabir5454 commented Jul 14, 2022 reply Follow Share @Shubham Sharma 2 thanks bro got it 0 votes 0 votes Please log in or register to add a comment.