ranteed service provisioning. 15.2.3 RSVP-TE for IP/(T-)MPLS Subnetwork After determination of the QoS and traffic parameters for a multimedia ses- sion using the SIP/SDP session layer signaling, QoS-guaranteed per-class- type connection must be established among the participant end terminal nodes [10]. In the network layer, connection establishment is accomplished by UNI and NNI signaling. For UNI signaling between the user terminal and the ingress edge router, RSVP-TE can be used to carry the connection © 2009 by Taylor & Francis Group, LLC SIP Handbook: Services, Technologies, and Security request [8]. MPLS [9] NNI signaling standard for inter-AS (autonomous sys- tem) domain network, however, is not yet well standardized to establish per- class-type QoS-guaranteed connections across multiple AS domain networks of different network operators. As a consequence, an efficient alternative tran- sit networking scheme must be provided SO as to configure a per-class-type QoS-guaranteed Differentiated Service (DiffServ) provisioning and to support the scalable CAC [10]. In order to support the per-class-type DiffServ provi- sioning, RSVP-TE must provide traffic engineering extensions SO as to deliver the traffic and QoS parameters. Recently, ITU-T and IETF are jointly developing transport MPLS (T-MPLS), which uses a subset of the existing MPLS standards and is designed specifically for application in transport networks [2]. T-MPLS is designed as a connection-oriented packet switched application. It offers a simpler imple- mentation by removing features that are not relevant to connection-oriented packet switching, and adding mechanisms that provide support of critical transport functionality. T-MPLS uses the same architectural principles of lay- ered networking that are used in synchronous digital hierarchy (SDH) and optical transport network (OTN), and provides a reliable packet-based tech- nology on the circuit-based reliable transport networking. The user agent in the multimedia terminal must provide the RSVP-TE cli