Why should duplicate ACKs trigger fast retransmit fast recovery instead of dropping back to slow start?
This is because for a small window size there will not be enough packets in transit to cause enough duplicate ACKs to be delivered. This mechanism, which is called fast recovery, effectively removes the slow start phase that happens between when fast retransmit detects a lost packet and additive increase begins.
What can you refer when the sender receives triple duplicate ACKs?
fast re-transmit
What is “fast re-transmit”? In TCP Reno, when three duplicate ACKs are received, TCP retransmits the packet presumed lost without waiting for timeout. This is called fast-retransmit.
How to calculate the delay of a packet?
Note: this formula is very simplistic and assumes there are no propagation delays, node processing delays or queuing delays etc. At t =N*L/R the 1st packet reaches the destination. At t =N*L/R +L/R the 2nd packet reaches the destination. At t = N*L/R +L/R+L/R the 3rd packet reaches the destination.
What does it mean when someone sends you a duplicate acknowledgement?
Typically, duplicate acknowledgements mean that one or more packets have been lost in the stream and the connection is attempting to recover. They are a common symptom of packet loss. In most cases, once the sender receives three duplicate acknowledgments, it will immediately retransmit the missing packet instead of waiting for a timer to expire.
What does duplicate ACK mean in network analyzer?
Most network analyzers will flag these packets as duplicate acknowledgements because the ACK number will stay the same until the missing packet is retransmitted, filling the gap in the sequence. Typically, duplicate acknowledgements mean that one or more packets have been lost in the stream and the connection is attempting to recover.
What happens if one of the packets goes missing?
If one of these packets in the stream goes missing, the receiving socket can indicate which packet was lost using selective acknowledgments. These allow the receiver to continue to acknowledge incoming data while informing the sender of the missing packet (s) in the stream.