CODEWITHSUNDEEP
socketsnetwork-programmingtcpwinsock
user4582812
user4582812

Reputation: 621

Is an RST packet guaranteed to arrive?

When a connection is terminated ungracefully (i.e. an RST packet has been sent to the other end), is the RST packet guaranteed to arrive? I mean how can the sending device know that the RST packet has been received by the other end if no ACK packet is sent back!

Upvotes: 0

Views: 140

Answers (2)

user207421
user207421

Reputation: 310860

RST packets are not ACKed, so there is no 'guarantee' in the sense you mean. However if you keep sending to an endpoint which has reset the connection, it will keep issuing RST packets.

Upvotes: 2

usr
usr

Reputation: 171178

It is not possible to make both sides of the communication agree whether the connection is supposed to be shut down or not in all cases. This is the Two Generals Problem which is unsolvable. The RST is more of a "courtesy" and performance optimization. It allows for early cleanup in almost all cases.

But if you pull the cable all packets go into a black hole and it is unclear whether it is just a momentary timeout or a permanent loss of connectivity.

Upvotes: 1

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