3. Connecting to the Push Service

3. Connecting to the Push Service

The push service MUST use HTTP over Transport Layer Security (TLS) [RFC2818] following the recommendations in [RFC7525]. The push service shares the same default port number (443/TCP) with HTTPS, but MAY also advertise the IANA-allocated TCP System Port (1001) using HTTP alternative services [RFC7838].

While the default port (443) offers broad reachability characteristics, it is most often used for web-browsing scenarios with a lower idle timeout than other ports configured in middleboxes. For WebPush scenarios, this would contribute to unnecessary radio communications to maintain the connection on battery-powered devices.

Advertising the alternate port (1001) allows middleboxes to optimize idle timeouts for connections specific to push scenarios with the expectation that data exchange will be infrequent.

Middleboxes SHOULD comply with REQ-5 in [RFC5382], which states that "the value of the 'established connection idle-timeout' MUST NOT be less than 2 hours 4 minutes".