Merge pull request #3557 from erickinnear/ek/per_cid_state

Note that state needs to be maintained for each issued CID if the peer chooses to use it

draft-ietf-quic-transport.md

@@ -1019,11 +1019,15 @@ connection IDs than its advertised active_connection_id_limit MUST close the
 connection with an error of type CONNECTION_ID_LIMIT_ERROR.
 
 An endpoint SHOULD supply a new connection ID when the peer retires a connection
-ID. If an endpoint provided fewer connection IDs than the peer's
-active_connection_id_limit, it MAY supply a new connection ID when it receives
-a packet with a previously unused connection ID.  An endpoint MAY limit the
+ID.  If an endpoint provided fewer connection IDs than the peer's
+active_connection_id_limit, it MAY supply a new connection ID when it receives a
+packet with a previously unused connection ID.  An endpoint MAY limit the
 frequency or the total number of connection IDs issued for each connection to
-avoid the risk of running out of connection IDs; see {{reset-token}}.
+avoid the risk of running out of connection IDs; see {{reset-token}}.  An
+endpoint MAY also limit the issuance of connection IDs to reduce the amount of
+per-path state it maintains, such as path validation status, as its peer
+might interact with it over as many paths as there are issued connection
+IDs.
 
 An endpoint that initiates migration and requires non-zero-length connection IDs
 SHOULD ensure that the pool of connection IDs available to its peer allows the