Content deleted Content added
→See also: * Stop-and-wait ARQ - and alpha order for the SAs |
stublike |
||
Line 1:
'''Alternating bit protocol''' (ABP)
[[Message]]s are sent from [[transmitter]] A to [[receiver (Information Theory)|receiver]] B. Assume that the [[channel (communications)|channel]] from A to B is initialized and that there are no messages in transit. Each message from A to B contains a data part and a one-bit sequence number, i.e., a value that is 0 or 1. B has two [[acknowledge character]]s that it can send to A: ACK0 and ACK1
▲'''Alternating bit protocol''' (ABP) means a simple [[data link layer]] [[network protocol]] that retransmits lost or corrupted messages.
When A sends a message, it
▲[[Message]]s are sent from [[transmitter]] A to [[receiver (Information Theory)|receiver]] B. Assume that the [[channel (communications)|channel]] from A to B is initialized and that there are no messages in transit. Each message from A to B contains a data part and a one-bit sequence number, i.e., a value that is 0 or 1. B has two [[acknowledge character]]s that it can send to A: ACK0 and ACK1. We assume that the channel may corrupt a message and that there is a way in which A and B can decide whether or not they have received a correct message. How and to what extent that is possible is the subject of [[coding theory]].
▲When A sends a message, it sends it continuously, with the same sequence number, until it receives an acknowledgment from B that contains the same sequence number. When that happens, A complements (flips) the sequence number and starts transmitting the next message.
When B receives a message that is not corrupted and has sequence number 0, it starts sending ACK0 and keeps doing so until it receives a valid message with number 1. Then it starts sending ACK1, etc.
Line 21 ⟶ 18:
==References==
{{FOLDOC}}
{{Telecomm-stub}}
{{DEFAULTSORT:Alternating Bit Protocol}}
| |||