ANSI SCTE 173-4 pdf free download

ANSI SCTE 173-4 pdf free download.Specification for Priority in Preferential Telecommunications over IPCablecom2 Networks.
6 Priority in IPCablecom2
Pnoritization entails obtaining a higher probability for completing a call or session. This capability should exist Ofl the access link and it must also be propagated throughout all relevant network entities to provide, as much as possible, end-to-end preferential treatment.
The framework standard [ANSI/SCTE 173-2] defines three aspects related to priority: the labelling, signalling and enabling mechanisms. The following clauses contain the specifications for the signalling and an enabling mechanism. As stated in the framework, placing the priority label in the data packets transmitted using RTP is not available. As a result, this Standard addresses only the requirements for signalling and enabling mechanisms. Several alternative methods are defined, which include the following:
• defining a new per hop behaviour for preferential traffic,
• a new shim layer protocol over IP,
• marking an application layer packet, and
• allocating a Diffserv code point, MPLS label, Ethernet Class of Service or other priority markings to label the packets associated with particular messages.
6.1 Priority signalling in IPCablecom2
The framework identifies the use of Resource-Priority and Accept-Resource-Priority headers defined in IIETF RFC 44121 to signal the priority in SIP request and response messages. IIETF RFC 44121 defines the term RP actor. This term refers to all entities that act upon the Resource-Priority header. These entities are the SIP proxies and the SIP user agents (UAs). In IPCablecom2, the SIP proxies are collectively called CSCF (call session control function). The UAs are the end points that initiate and receive a session: they are respectively the SIP UAC (user agent client) and SIP UAS (user agent server). These will both be referred to as the SIP VA.
There are two options for handling the R-P header. In the first option, the SIP UA shall include the R-P header, as described in section 4.7.1 of [IETF RFC 4412], in the request messages when requesting sessions in support of preferential telecommunication services. In the second option, a proxy CSCF shall generate and insert an appropriate R-P header based upon the information received in the session set-up request. The requirements to he supported by the functional entities in IPCablecom2 networks are included in clause 7.
The R-P header syntax, as defined by IIETF RFC 4412], requires defining a namespace, values for priority levels, an algorithm to be used by the RP actors and new response (error) codes relevant for this namespace. The namespace definition must be registered with lANA.
IIETF RFC 4412] defines two algorithms for providing priority even though the new namespace definition may specify other algorithms. The two algorithms defined by the RFC are preemption and priority queuing.
Appendix I illustrates the components required for a namespace definition according to [IETF RFC 4412]. Annexes A to E identify the namespace specific to each ITU region.
6.2 Priority-enabling mechanisms in IPCablecom2
Appendix II of [b-ITU-T J.360] and FANS L/SCTE 159-1] define interfaces to set up policies and control for enabling QoS to support resource management for new services, including those that require preferential treatment. Even though QoS is not meant to imply priority, one of the considerations for the QoS architecture in IPCablecorn2 networks is prioritization for sessions. ANSI SCTE 173-4 pdf download.