Sliding Window Protocols

Sliding Window Protocols By ABHISHEK KUMAR SINGH REG. NO. 07RWSCA001

Sliding window Protocol These protocols comes under the data link layer.  It provides services to the network layer.  It’s a bidirectional protocol. It means sender deleted the frames when get the acknowledgment. 

sender

receiver

Purpose An incremental Specification. Novel Enhancements to local control a soft-state. Masking the overhead of protocol layering.

Types Of Windows Sender Window. Sender maintains a set of sequence number corresponding to frame it is permitted to send. These frames are said to fall within the sending window.

Receiving Window. The receiver also maintains a receiving window corresponding to the set of frames, it is permitted to accept.

Types of sliding window protocols One-Bit sliding window protocols. Go Back N sliding window protocols. Selective Repeat sliding window protocols.

One-Bit sliding window protocols. Sender sends a frame to receiver and receiver receives that frame and send a new frame and acknowledgment to sender. Eg: A B A1 B1+Ack A2 B2+A2 Ack

Go Back N sliding window protocols.

D

D

5

4

3

Ac k

D

Ac k

E

Ac k

1

2

0

Ac k

Ac k

1

Ac k

0

In this the receiver simply discard all subsequent frame, sending no acknowledgment for the discarding frame. 0 1 2 3 4 5 sender 2 3 4 5 6 7

2

3

4

5

6

7

Error Discarded

Receiver N=2, it is an error . After 2 the sender didn’t get the acknowledgment. So 3, 4, 5 is discarded and

Selective Repeat sliding window protocols. In this a bad frame that is received is discarded, but good frame received after it are buffered. When the sender times out, only the oldest unacknowledged frame is retransmitted. Eg: sender

Error

7

Ac

Ac

Ac k

3

4

5

2

6

7

8

k

Ac k

k

9

Receiver

10

8

8

6

7

Ac k

3

E

6

Ac k

Ac k

1

2

Ac k

Ac k

0

5

2

4

1

3

5

2

4

1

0

0

9

10

THANKS…..