10 / 12 Application Layer & Protocols

One Segment Lost

A page pulls 40 small assets over a single HTTP/2 connection, one stream each, all in flight. A single TCP segment carrying part of asset 7 is lost in the network.

What happens to the other 39 while that segment is retransmitted?

A

All 40 stall, exactly as they would have under HTTP/1.1 with six parallel connections, so multiplexing changes nothing about behavior under loss.

B

They stall too: TCP delivers its byte stream in order, so frames for every stream that arrived after the lost segment sit in the receiver's buffer until the retransmission fills the hole.

C

Only asset 7 stalls: each HTTP/2 stream has its own flow-control window and its own delivery ordering, so a gap in one stream does not hold up the others.

D

Nothing stalls: HPACK adds forward error correction across frames so a single lost segment is reconstructed without a retransmission.