Add ping spec

ping/ping.md

@@ -0,0 +1,56 @@
+# Ping <!-- omit in toc -->
+
+| Lifecycle Stage | Maturity      | Status | Latest Revision |
+| --------------- | ------------- | ------ | --------------- |
+| 3A              | Working Draft | Active | r0, 2022-11-04  |
+
+Authors: [@marcopolo]
+
+Interest Group: [@marcopolo], [@mxinden], [@marten-seemann]
+
+[@marcopolo]: https://github.com/mxinden
+[@mxinden]: https://github.com/mxinden
+[@marten-seemann]: https://github.com/marten-seemann
+
+# Table of Contents <!-- omit in toc -->
+- [Protocol](#protocol)
+- [Diagram](#diagram)
+
+# Protocol
+
+The ping protocol is a simple request response protocol. The client sends a
+payload of 32 random bytes, and the server responds with the same 32 bytes. The
+client then measures the RTT from the time it wrote the bytes to the time it
+received the bytes. The client may repeat the process by sending another payload
+with random bytes, so the server _should_ loop and echo the next payload. The
+client may close the write side of the stream after sending a payload, the
+server _should_ finish writing the echoed payload and then exit the loop and
+close the stream.
+
+The protocol id is `/ipfs/ping/1.0.0`.
+
+# Diagram
+
+![Ping Protocol Diagram](./ping.svg)
+
+<details>
+  <summary>Instructions to reproduce diagram</summary>
+
+From the root, run:  `plantuml -tsvg ping/ping.md`
+
+```
+@startuml
+skinparam backgroundColor white
+
+entity Client
+entity Server
+
+== /ipfs/ping/1.0.0 ==
+loop until Client closes write
+    Client -> Server: 32 random bytes
+    Client <- Server: Same 32 random bytes
+end
+@enduml
+```
+
+</details>