| Internet-Draft | ALPN usage for SIP | August 2021 |
| Johansson | Expires 25 February 2022 | [Page] |
Many SIP specifications use other protocols in addition to the core SIP protocol, like HTTP and MSRP. In order to be able to use multiple protocols on the same port with TLS, a TLS Application Protocol Negotiation Extension (ALPN) protocol ID is needed (RFC 7301 [RFC7301]). This document registers "sip" as the ALPN protocol ID for the SIP protocol.¶
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A modern SIP server not only supports the Session Initation Protocol (RFC 3261 [RFC3261]), but also needs to support HTTP and possibly other related protocols, like MSRP. To reduce the number of ports used, a SIP server supporting Transport Layer Security (TLS) can support multiple protocols on the same port, provided the clients signal protocol usage with ALPN.¶
Registration following the specification in RFC 7301 [RFC7301]¶
This document was inspired by registration feedback from Rich Salz.¶
This document registres a new ALPN in the "Application-Layer Protocol Negotiation (ALPN) Protocol IDs" registry under the existing "Transport Layer Security (TLS) Extensions" heading.¶
This document modifies the behaviour of compliant SIP servers when being used by compliant SIP implementations (servers and clients). It does not add any known security issues to the protocol.¶
For security considerations related to usage of ALPN in TLS, see RFC 7301 [RFC7301]¶