The Assignment of the Information Field and Protocol Identifier in the Q.2941 Generic Identifier and Q.2957 User-to-user Signaling for the Internet Protocol
Extracted elements (24)
For long-lived session signaling, the Generic Identifier IE was chosen over B-LLI, B-HLI, and User-user IEs to carry the session identifier because it best matches the original purpose of these elements — the Generic Identifier is specifically designed for identifier transfer between c-planes.
Forwarding the IP setup protocol (e.g., RSVP) as an information element in B-ISDN signaling (simultaneous QoS session + ATM VC establishment) is preferred over sequential establishment because it simplifies admission control, simplifies watchdog timer processing, and enables QoS negotiation. However, PVC-based QoS sessions cannot use this approach, so both procedures must be supported.
The IPv4 and IPv6 session identifiers are intended only for explicit reservation (5-tuple: src/dst address, protocol, src/dst port). Wild card associations are explicitly deferred: if needed in the future, a different Identifier type value will be used rather than extending the current Session type.
The Generic Identifier is designed for transfer of identifiers between c-planes, while User-to-user Signaling is designed for transfer of user data via c-planes. Unlike the Generic Identifier, User-to-user Signaling supports interworking with the user-user IE in Q.931 N-ISDN signaling. The ATM network may check the contents of Generic Identifier IEs but does not check User-user IE contents.
When a B-ISDN signaling message containing a User-user IE enters an ATM network that does not support User-to-user Signaling, the network clears the call, discards the information element, or discards the signaling message (per Q.2931 sections 4.5.1 and 5.6.8.1, Q.2957 section 1.9, and Q.2971 annex D).
In the Experiment/Organization specific identifier, the first 3 octets in the Identifier value field must contain the Organizationally Unique Identifier (OUI) as specified in IEEE 802-1990 section 5.1.
The calling party should confirm that the CONNECT or ADD PARTY ACK response contains a User-user information element. The called party may not respond with the same user information received from the calling party.
To enable reliable Generic Identifier information element transfer, when the calling party sends a SETUP or ADD PARTY message with up to three Generic Identifier IEs, the CONNECT or ADD PARTY ACK returned by the called party must contain at least one Generic Identifier IE.
To enable reliable User-user information element transfer, when the calling party sends a SETUP or ADD PARTY message with a User-user IE, the CONNECT or ADD PARTY ACK returned by the called party must contain a User-user IE.
The Generic Identifier information element (IE identifier 0x7F) enables transfer of identifiers between end-to-end users in the ATM network. It is defined in Q.2941.1 and Q.2941.2 as optional for Q.2931 and Q.2971 UNI signaling. Up to three Generic Identifier IEs may appear in SETUP, ALERTING, CONNECT, RELEASE, RELEASE COMPLETE, ADD PARTY, PARTY ALERTING, ADD PARTY ACK, ADD PARTY REJECT, DROP PARTY, and DROP PARTY ACK messages.
The Identifier related standard/application field in the Generic Identifier IE identifies the protocol using the identifier. Values assigned for Internet protocols: 0x03=IPv4, 0x04=ST2+, 0x05=IPv6, 0x06=MPLS.
The Identifier type field in the Generic Identifier IE specifies the type of identifier carried. Assigned values: 0x01=Session, 0x02=Resource, 0x10-0xFD=Reserved for IANA assignment, 0xFE=Experiment/Organization specific.
The User-user information element uses Protocol discriminator value 0x06 to indicate Internet protocol/application content. The first octet of the User information field is the Internet protocol/application identifier. Assigned values: 0x00=Reserved, 0x01=Reserved for ST2+, 0x02=RSVP message, 0x03-0xFD=Reserved for IANA assignment, 0xFE=Experiment/Organization specific, 0xFF=Reserved.
IANA assignment registry for the Identifier type field in the Q.2941.2 Generic Identifier IE when the Identifier related standard/application field is IPv4, ST2+, IPv6, or MPLS. Values 0x10-0xFD are reserved for IANA assignment via IETF Consensus action per BCP 26.
IANA assignment registry for the Internet protocol/application identifier field in the Q.2957 User-user IE when the Protocol discriminator is Internet protocol/application (0x06). Values 0x03-0xFD are reserved for IANA assignment via IETF Consensus action per BCP 26.
The information field and protocol identifier assignments specified in this document do not weaken the security of B-ISDN signaling. In the called party, if the incoming SETUP message contains a calling party number that is verified and passed by the ATM network or provided by the network, that number can be used for partial calling party authentication to strengthen security.
The Experiment/Organization specific format in the User-user IE: Protocol discriminator=0x06, identifier=0xFE, followed by a 3-octet OUI (IEEE 802-1990 section 5.1) and then organization-specific information.
The Experiment/Organization specific identifier in the Generic Identifier IE has Identifier type=0xFE. The first 3 octets of the Identifier value field must contain the Organizationally Unique Identifier (OUI) as specified in IEEE 802-1990 section 5.1.
The Generic Identifier information element format: octet 1 is the IE identifier (0x7F), octet 2 is the IE instruction field with coding standard and action indicator, octets 3-4 are the length, octet 5 is the Identifier related standard/application field, octet 6 is the Identifier type, octet 7 is the Identifier length, and octets 8+ are the Identifier value. Maximum total length is 63 octets.
The IPv4 session identifier has Identifier type=Session (0x01) and Identifier length=13 octets. The Identifier value field contains in order: Source IPv4 address (4 octets), Destination IPv4 address (4 octets), Protocol (1 octet), Source Port (2 octets), Destination Port (2 octets).
The IPv6 session identifier has Identifier type=Session (0x01) and Identifier length=37 octets. The Identifier value field contains in order: Source IPv6 address (16 octets), Destination IPv6 address (16 octets), Protocol (1 octet), Source Port (2 octets), Destination Port (2 octets).
The MPLS VCID identifier has Identifier type=Resource (0x02) and Identifier length=4 octets. The Identifier value field contains the 4-octet MPLS VCID as defined in RFC 3038.
The RSVP message format in the User-user IE: Protocol discriminator=0x06, Internet protocol/application identifier=RSVP message (0x02), followed by the full RSVP message. SETUP may carry RSVP Resv, CONNECT may carry RSVP ResvConf, and RELEASE may carry RSVP ResvErr or ResvTear.
The User-user information element format (IE identifier 0x7E): octet 1 is the IE identifier, octet 2 is the IE instruction field, octets 3-4 are the length, octet 5 is the Protocol discriminator, and octets 6+ are the User information field. Maximum total length is 133 octets.