| Internet-Draft | HTTP Datagram PING | October 2021 |
| Schwartz | Expires 7 April 2022 | [Page] |
This draft defines an HTTP Datagram Format Type for measuring the functionality of a Datagram path.¶
This note is to be removed before publishing as an RFC.¶
Discussion of this document takes place on the mailing list (masque@ietf.org), which is archived at https://mailarchive.ietf.org/arch/browse/masque/.¶
Source for this draft and an issue tracker can be found at https://github.com/bemasc/h3-datagram-ping.¶
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The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.¶
PING is an HTTP Datagram Format Type [I-D.draft-ietf-masque-h3-datagram]. It has no Additional Data.¶
PING Datagrams have the following format:¶
PING {
Sequence Number (i),
Opaque Data (..),
}
All Sequence Number and Opaque Data values are potentially valid.¶
The sender emits a PING Datagram with any even Sequence Number and any Opaque Data. Upon receiving a PING Datagram with an even Sequence Number, the recipient MUST reply with a PING Datagram whose Sequence Number is one larger, with empty Opaque Data.¶
Intermediaries MUST forward PING Datagrams without modification, just like any other HTTP Datagram.¶
PING Datagrams can be used to characterize the end-to-end HTTP Datagram path associated with an HTTP request. For example, HTTP endpoints can easily use PING Datagrams to estimate the round-trip time and loss rate of the HTTP Datagram path.¶
PING Datagrams are also suitable for use as DPLPMTUD Probe Packets [RFC8899]. This enables endpoints to estimate the HTTP Datagram MTU of each Datagram path, in order to avoid sending HTTP Datagrams that will be dropped.¶
Note that these path characteristics can differ from those inferred from the underlying transport (e.g. QUIC), if the HTTP request traverses one or more HTTP intermediaries (see Section 3.7 of [I-D.draft-ietf-httpbis-semantics]).¶
IANA is directed to add the following entry to the "HTTP Datagram Format Types" registry:¶
Thanks to Alex Chernyakhovsky for constructive input.¶