Infosim Whitepaper VoIP quality monitoring in Cable-TV networks The wise adapt themselves to circumstances, as water moulds itself to the pitcher. Chinese Proverb Infosim GmbH & Co KG http://www.infosim.net Asia Pacific Region Phone: +65 6327 4240 Fax: +65 6327 4474 EMEA Region Phone: +49 931 20592 200 Fax: +49 931 20592 209 Whitepaper Contents Challenges and Problems Technical Background Information Requirements and Solutions VoIP Performance Management Advantages and Benefits
Introduction Part One Introduction End user expectations Voice quality issues Multi-vendor management Operation support systems
VoIP for Cable Operator Many cable companies have been closely monitoring VoIP's evolution and examining how it could enhance their business. VoIP enables these vendors to market a wider array of value-added services, such as unified messaging, video calling and Web conferencing. In preparation for delivering VoIP services, cable companies had to address a number of technological challenges. Cable-based network operators, who want to introduce VoIP services are faced with the challenge of how to best carry both real-time applications and traditional data traffic. VoIP, the preeminent real-time application, presents unique hurdles for cable companies: - Meeting End-User Expectations Users demand from VoIP the same high quality standards, high reliability and crisp voice quality, as the familiar Public Switched Telephone Network (PSTN) has delivered for decades. - VoIP Is A Network-Performance-Sensitive Service VoIP is a highly performance-sensitive, real-time service that is especially impacted by network impairments, such as network delay and signal loss. - VoIP Is A Complex And Multi-vendor Application Yesterday's single-vendor, integrated switches are replaced in today's converged networks with multiple network components gateways, routers, soft-switches, session border controllers, feature and record keeping servers from different suppliers, a complex environment made even more difficult by the fact that no vendor can provide full service visibility. - Traditional Monitoring Tools Are Inadequate Traditional telephony monitoring tools and general-purpose IP network management tools do not offer the service-wide visibility, structured performance information, or VoIP-specific metrics and key performance indicators needed by network operators, to monitor VoIP quality. Individually, each of the above is a challenge, but combined they pose an even more formidable problem.
Requirements Part Two Requirements Event Management Root-cause analysis End-to-End management Service level movement Subscriber support
VoIP for Cable Operator To overcome these challenges, and provide consistently high-quality VoIP services to retail and wholesale customers, cable operators need to: - Identify, isolate, and resolve problems StableNet PME enables providers to quickly find and fix problems using a variety of tools based on multiple familiar measurement protocols (SNMP, RMON, Netflow, SAA) providing these capabilities, including: call quality, root-cause analysis; continuous active and passive performance monitoring; network path analysis; and on-demand and threshold-based conditional alerting and troubleshooting. - Evaluate the performance of partner networks With StableNet PME, cable operators providers gain not only an understanding of the performance of their own networks, but also insight into the operation of their partners' networks by constantly monitoring the performance that their IP and PSTN peering and wholesaling partners deliver. - Continuously monitor service quality By continuously measuring the performance of both live and actively generated calls and other traffic flows, StableNet PME enables cable operators to know, at all times, whether they are meeting target service quality goals, and initiates early warning alerts for below-standard quality and failures through outages. - Satisfy customer demands for service-specific, verifiable, Service Level Agreements StableNet PME provides the ability to specify, monitor, and report on service level agreement (SLA) compliance. Administrators create VoIP service-specific SLAs customized for individual subscribers or subscriber groups, the StableNet PME continuously monitors each SLA for compliance, and provides personnel and subscribers view real-time and historical SLA performance reports using administrative and end-user reporting portals. - Determine how to best support new services The only constant in today's multi-service networks is change, and administrators need to continually assess how well their infrastructure can support new services, such as VoIP. With StableNet PME administrators can a priori assess and objectivley measure the effect of VoIP or other real-time applications on existing applications and the influence of existing applications on the new VoIP service or real-time application.
Infosim Whitepaper Background - VoIP in cable networks A customer of a cable operator initiates a call. This call will then be coded by the MTA (Media Terminal Adapter) and a dedicated, QoS-capable connection via the DOCSIS (Data Over Cable Service Interface Specification standard) network will be established to the CMTS (Cable Modem Termination System) using the RSVP/RSVP+ Protocol (RSVP+ is an improved version of RSVP). The voice packets are transmitted in the form of RTP/UDP/IP-Packets. The software of the cable modem is based on the DOCSIS standard and communicates with the CMTS (Cable Modem Termination System), in order to obtain the required QoS. The CMTS is the connector between the DOCSIS network on the customer side and the IP backbone on the network side. The CMTS transmits these voice packets into the IP backbone to a router closest to a handover point, where either a softswitch decodes the VoIP packets and terminates them in the PSTN, or where the VoIP traffic flows will be passed on to an external PSTN termination provider. Network architecture for VoIP in a HFC network Call Management Server /Gate Controller Softswitch HFC/EuroDODCIS IP-Backbone Telefon MTA Cable Modem CMTS Cu stomer Head end Cable operator Record Keeping Server IP Backbone Cable operator Illustration 1: Network Architecture
Performance Management Part Three Solution Quality factors Technical requirements Examples reports Benefits and advantages
VoIP for Cable Operator How to measures and evaluate VoIP quality StableNet PME obtains and visualizes the measurements. StableNet PME configures via SNMP the SAA router/cmts pair. Both network elements, the router and the CMTS, simulate in regular intervals VoIP calls and measure the transport quality of these VoIP flows in the backbone. The following parameters are obtained and visualized by StableNet PME: - the MOS-Value - link throughput - link utilization - Jitter - Delay - errors - packet loss - buffer losses - buffer discards - call set-up times - post-dial delay Full compliance with ITU-Standards P.862 and G.107. Quality measurement of VoIP traffic flows between CMTS and core router in cable operator networks based on SAA Headend Cable operator Backbone Cable operator CMTS As of IOS V. 12.3 (4) T IP-Backbone Softswitch HFC/EuroDODCIS VoIP flow VoIP flow SAA StableNet PME Monitoring Agent SAA Measurements StableNet PME Illustration 2: Measurement Framework The StableNet PME agent, a software-based agent, reads in regular intervals the measurements from both the CMTS and the core network router, compares them with pre-defined threshold levels and writes them into the central StableNet PME Database. If measurements indicate quality above or below threshold levels the Agent sets off an alert, which can be commu-
VoIP for Cable Operator nicated via a script or email into the central network management solution. Prerequisites (Pure Cisco environment): Core network routers and CMTSs ubr 7200 series support these SAA parameters as of IOS version 12.3(4)T. Prerequisites (non-cisco or mixed environments): Juniper routers support SAA as of OS version 7.5, in other environments a PC-based SAA-Emitter has to be installed closed to targeted network components. StableNet PME Benefits for cable operators Providers that deploy StableNet PME network management solution for VoIP services in their core networks realize the following benefits: - Faster problem identification, isolation, and resolution within their network and at peering points - Reduction in costly outages and service degradations - Faster time to market with the right services for their network - Shorter mean time to repair (MTTR) - Realistic SLAs that showcase the strengths of their network - Seamless Integration with back office Operations Support Systems - Cost-efficient solution for IP service level verification building on existing hardware components (Cisco environments only) - First carrier-class management system for Cisco SAA functionalities - Provision, collect, audit and report SAA results via StableNet PME less churn among customers and high customer satisfaction levels
VoIP for Cable Operator
Infosim Whitepaper Infosim, StableNet and the Infosim logo, whether or not appearing with the registered symbol, are registered trademarks of Infosim GmbH & Co KG. All third-party trademarks and/or company names are the properties of their respective owners and are hereby acknowledged. This document contains summarized information that will be subjected to periodic changes. At the time of writing, Infosim has made all reasonable efforts to ensure that the statements contained within this document are accurate. No warranties are expressed or implied. Applicability or provision of services is subject to Due Diligence. Copyright 2005 Infosim Asia Pacific Pte Ltd. All rights reserved