Packet Loss and Packet duplication

tcp udp network-protocols duplication packet-loss
source.rar picture source.rar · Oct 13, 2012 · Viewed 19.4k times · Source

I am trying to find out what the difference between packet loss and packet duplication problems is. Does anyone know what 'packet duplication' is all about? Is it the same as re-transmitting packets when a loss is detected in TCP?

Answer

Heisenbug picture Heisenbug · Oct 13, 2012

No. In TCP delivery of "packets" is reliable(I think the term data should be better in this case, since it's a stream oriented protocol).

Packet loss and duplication are problem related to unreliable protocols datagram oriented like UDP. In UDP when you send a datagram this could arrive duplicated, out of order or even don't arrive at all.

Is it the same as re-transmitting packets when a loss is detected in TCP?

Yes and no. Let's say that TCP uses internally an ack mechanism to detect missing data, and automatically retrasmit them. So the missing data are trasparent to the user, and handled by the protocol itself.

Does anyone know what 'packet duplication' is all about?

In certain situations could happen that IP packets are duplicate along the path to their destination. For example a router could decide to forward incoming traffic thorugh 2 different network interfaces. In this case could happen that both IP packets will reach the destination.

TCP handle duplicated IP packets problem, so you don't care about them.

UDP doesn't handle them. When you receive a datagram it's not guaranteed that you didn't have received the same datagram before. You should check it.

Related questions

Is SMTP based on TCP or UDP?

Is SMTP based on TCP or UDP ? I really can't confirm it . In my opinion, SMTP should be based on UDP, but someone told me that is must be TCP.

Read More
TCP vs UDP - What is a TCP connection?

What exactly is a TCP connection? I understand there isn't a physical connection from the client to server. Is this connection just the client's socket being linked with the new socket created by the server after the three-way-handshake? Thereafter once …

Read More
Why is it possible to use the same port on TCP and UDP at the same time?

I've seen while searching that it is possible to use two different programs on the same computer communicating over the network using the same port and same network interface provided one use UDP and the other TCP. However I didn't …

Read More