SELECTIVE REJECT ARQ

Using selective reject ARQ, the only frame retransmit are those that receivers a negative ack. As are ARQ is more efficient then go-back N b/c it minimizes the amount of retransmission. The receiver must maintain a buffer large enough to save SR-ARQ frames until the frames will be retransmitted.

SCENARIO

Window size equal to through 73 bits sequence number.

1. Station a sends frames 0 to 7 through 6 to station being.

2. Station B receiver all frames and ACK RR7.

3. Because of the noise RR7 is lost.

4. Retransmit frame 0.

5. Station B receiver or accept frames 0, 7, 0, 1, 2, 3, 4.

6. It assume that the frame number 7 has been lost. So it will be retransmitted as a new frame 0.

Image

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s