IP Packet: TCP Tahoe and Reno

July 13, 2004

TCP Tahoe and Reno

Sometime when you read about TCP you'll see some TCP variant , in fact because there are some algorithm for instance Tahoe,Reno,New-Reno & so on.
I'll explain the much brief of Tahoe and Reno but if you're interested in so i recommend that read the details.Tahoe by Jacobson assumed the one way of detecting a loss packet in TCP is using timeout, it known as the round trip time (RTT) which named Retransmit time out (RTO).if the ack isn't received before this RTO then the sender should be sure that the packet is lost and must
retransmit. another way to detect loss packet in TCP Tahoe is sending duplicate acknowledgments, it means when the receiver don't get packet sequence n , it send duplicate acknowledgments for that sequence number.
Typically, after two acknowledgments TCP Tahoe knows the packet is lost and after three acknowledgments it retransmit the packet to the receiver.
This algorithm is called Fast Retransmit and it doesn't deal when more than one packets lost within a single window of data.

TCP Reno improvements over Tahoe by changing the way. The idea is that the only way for a loss to be detected via a timeout and not via the receipt of a duplicate ack is when the flow of packets and acks has completely stopped also Reno introduce a mechanism called Fast recovery which governs the re-transmission of new data until non-duplicate acks are received.

Posted by Mehrdad at July 13, 2004 05:51 PM