diff --git a/draft-ietf-quic-transport.md b/draft-ietf-quic-transport.md index 63d4f24469..227292b11f 100644 --- a/draft-ietf-quic-transport.md +++ b/draft-ietf-quic-transport.md @@ -4091,13 +4091,16 @@ fragmentation on the path. A client MUST expand the payload of all UDP datagrams carrying Initial packets to at least the smallest allowed maximum datagram size of 1200 bytes by adding PADDING frames to the Initial packet or by coalescing the Initial packet; see -{{packet-coalesce}}. Similarly, a server MUST expand the payload of all UDP -datagrams carrying ack-eliciting Initial packets to at least the smallest -allowed maximum datagram size of 1200 bytes. Sending UDP datagrams of this size -ensures that the network path supports a reasonable Path Maximum Transmission -Unit (PMTU), in both directions. Additionally, a client that expands Initial -packets helps reduce the amplitude of amplification attacks caused by server -responses toward an unverified client address; see {{address-validation}}. +{{packet-coalesce}}. Additionally, a client that expands Initial packets helps +reduce the amplitude of amplification attacks caused by server responses +toward an unverified client address; see {{address-validation}}. + +Similarly, a server MUST expand the payload of all UDP datagrams carrying +ack-eliciting Initial packets to at least the smallest allowed maximum datagram +size of 1200 bytes. Note that unexpanded Initial packets extend the peer's +idle timeout, even if the path is not capable of carrying the full MTU. +Sending UDP datagrams of this size ensures that the network path supports a +reasonable Path Maximum Transmission Unit (PMTU), in both directions. Datagrams containing Initial packets MAY exceed 1200 bytes if the sender believes that the network path and peer both support the size that it chooses.