Telephony Routing over IP (TRIP) Attribute for Resource Priority
RFC 5115
Document | Type |
RFC - Proposed Standard
(January 2008; Errata)
Was draft-carlberg-trip-attribute-rp (individual in rai area)
|
|
---|---|---|---|
Authors | Piers O'Hanlon , Ken Carlberg | ||
Last updated | 2015-10-14 | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Reviews | |||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 5115 (Proposed Standard) | |
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Cullen Jennings | ||
Send notices to | p.ohanlon@cs.ucl.ac.uk |
Network Working Group K. Carlberg Request for Comments: 5115 G11 Category: Standards Track P. O'Hanlon UCL January 2008 Telephony Routing over IP (TRIP) Attribute for Resource Priority Status of This Memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited. Abstract This document defines a new attribute for the Telephony Routing over IP (TRIP) protocol. The attribute associates protocols/services in the PSTN offering authorized prioritization during call setup that are reachable through a TRIP gateway. Current examples of preferential service in the Public Switched Telephone Network (PSTN) are Government Emergency Telecommunications Service (GETS) in the U.S. and Government Telephone Preference Scheme (GTPS) in the U.K. The proposed attribute for TRIP is based on the NameSpace.Value tuple defined for the SIP Resource-Priority field. 1. Introduction An IP telephony gateway allows nodes on an IP-based network to communicate with other entities on the circuit switched telephone network. The Telephony Routing over IP (TRIP) protocol [rfc3219] provides a way for nodes on the IP network to locate a suitable gateway through the use of Location Servers. TRIP is a policy- driven, inter-administrative domain protocol for advertising the reachability, negotiating the capabilities, and specifying the attributes of these gateways. The TRIP protocol is modeled after BGP-4 [rfc4271] and uses path- vector advertisements distributed in a hop-by-hop manner (resembling a Bellman-Ford routing algorithm) via Location Servers. These Location Servers are grouped in administrative clusters known as Internet Telephony Administrative Domains (ITADs). A more extensive framework discussion on TRIP can be found in [rfc2871]. Carlberg & O'Hanlon Standards Track [Page 1] RFC 5115 Resource Priority Attribute January 2008 This document defines a new attribute that has been registered with IANA. The purpose of this new attribute, and the rationale behind its specification, is explained in the following sections. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [rfc2119]. 2. Emergency Telecommunications Service Emergency Telecommunications Service is a broad term that refers to the services provided by systems used to support emergency communications. One example of these systems is the U.S. Government Emergency Telecommunications Service (GETS). This system currently operates over the U.S. Public Switched Telephone Network (PSTN) as a pay-per-use system by authorized personnel. It uses the T1.631-1993 ANSI standard [ANSI] to signal the presence of the National Security / Emergency Preparedness (NS/EP) codepoint in an ISDN User Part (ISUP) Initial Address Message (IAM) for Signaling System No. 7 (SS7). A key aspect of GETS is that a signaling standard in the U.S. PSTN is used to convey the activation/request of the GETS service. From a protocol perspective, other examples of priority (and which can be argued as emergency/disaster related) standards are the H.460.4 ITU [itu460] standard on Call Priority designation for H.323 calls, and the I.255.3 [itu255] ITU standard on Multi-Level Precedence and Preemption Service. The latter has been integrated into private telephony systems like AUTOVON. In both cases, signaling codepoints exist to distinguish telephony calls by authenticated and prioritized end-user from the normal end-user. The form of this distinction varies and is outside the scope of this document. [rfc3689] and [rfc3690] provide additional information on ETS and its requirements. 3. SIP Resource-Priority Effort The initial discussions in the IEPREP working group list, along with the presentation at the Adelaide IETF [ADEL00], led to strawman requirements to augment SIP to have the ability to prioritize call signaling. This effort was then advanced formally in the SIPPING working group so that SIP would be able to prioritize access to circuit-switched networks, end systems, and proxy resources for emergency preparedness communication [rfc3487]. The requirements in [rfc3487] produced the corresponding documentShow full document text