QSIG Separation of Bearer and Signaling in Avaya Communication Manager

Transcription

1 QSIG Separation of Bearer and Signaling in Avaya Communication Manager White Paper July 2003 IP Telephony Contact Centers Unified Communication Services

2 T able of Contents: Section 1: Introduction Section 2: QSIG "Virtual Private Networks" What they are and how they work Section 3: Primary Benefits of QSIG Separation of Bearer and Signaling 3.1: Assure Voice Quality 3.2: Enterprise-wide Ubiquity of Communications 3.3: Enabling "Killer Apps" 3.4: Communications Continuity 3.5: Reduce Expenses Section 4: Conclusion Section 5: Avaya QSIG Glossary

3 Section 1: Introduction QSIG is part of the Avaya Communication Manager offer to support enterprise-wide feature-transparent networking. QSIG is also an ISO standard for interoperability between communications platforms provided by disparate vendors. A new QSIG feature "Separation of Bearer and Signaling" is implemented in Release 1.3 of Communication Manager. This feature enables enterprise-wide virtual networks of Avaya servers over public networks. Out-of-band signaling is provided via Internet Protocol over IP, Frame Relay, or ATM networks. (A glossary of related terms is provided on the last page.) This white paper describes Avaya s implementation of QSIG Separation of Bearer and Signaling, and explains the advantages of both SBS and QSIG in terms of expense reduction, enhanced productivity, reliability and application deployment. Section 2: QSIG "Virtual Private Networks" What they are and how they work QSIG, which is defined as the Q.931 standard by the International Standards Organization, is an internationally accepted method of networking communication systems. Avaya is an industry leader in the implementation of QSIG networking, utilizing a full complement of QSIG functionality including QSIG supplementary services and route optimization features. Avaya Communication Manager allows QSIG to be used to provide feature transparency and to link multiple communications platforms. QSIG networks can scale to serve over 1 million telephony endpoints that can be deployed across and between international boundaries. The new QSIG Separation of Bearer and Signaling (SBS) feature will economically enable virtual networks of software-enabled nodes to access bandwidth on demand over the PSTN. This feature is supported in Avaya Communication Manager 1.3. Avaya Communication Manager supports both QSIG and Distributed Communication System (DCS and DCS+) networking. DCS and DCS+ are legacy Avaya-specific feature-transparent networking protocols that are common in North America and other regions. For the foreseeable future, Avaya intends to continue to support and make available DCS and DCS+ in its present form. QSIG functionality is continually being enhanced. Communication Manager QSIG can be used to support enterprise-wide 6 or 7-digit expanded dial plans, as well as many other enhanced features. DCS+ is an improvement over traditional DCS, which always requires expensive dedicated T1, E1, or ISDN PRI links between nodes. There are two basic types of DCS+ networks. The most commonly occurring type involves dedicated direct T1, E1, or PRI connections between nodes. The second type works with ISDN public switched network trunks established between each node and the point of presence of a service provider s virtual ISDN network (typically AT&T SDN or MCI N-Quest). In this environment, Temporary Signaling Connections are permanently established to support active calls between nodes. These DCS+ customers have been taking advantage of reduced networking costs because DCS+ uses Temporary 1

4 Signaling Connections (TSCs) over the public switched telephone network (PSTN); this facilitates optimal use of PSTN facilities. The TSCs can reduce the amount of bandwidth and associated PSTN costs needed to support feature-transparent networks, since dedicated ISDN private-line links between nodes are not required. QSIG is a viable alternative to DCS and DCS+ now that SBS is available in Communication Manager. The ability to provide signaling over an IP network provides the benefit of feature transparency while maximizing the capability of PSTN facilities to assure toll quality voice traffic. This enables a functional equivalent to DCS+ without requiring dependence on the limited set of specific network services providers that provide compatibility with DCS+. A typical SBS call flow is illustrated below. Note that all messages shown are the SBS call signaling messages over the SBS IP WAN link. The SBS signaling link implementation is not based on an international standard, as is QSIG itself. Avaya s SBS capability is intended to support a network of Avaya Media Servers and Avaya Media Gateways (in the absence of comparable international standards to accomplish this function). Avaya Media Server and Media Gateway A QSIG Signaling Channel "SBS" IP Signaling WAN Link Avaya Media Server and Media Gateway B QSIG Signaling Channel QSIG Bearer Channel PSTN Access PSTN PSTN Access QSIG Bearer Channel Avaya QSIG Separation of Bearer and Signaling Capability Each SBS call has two components: an IP session to carry the SBS call control and QSIG private networking signaling information, and a bearer call over a switched public network. SBS will associate these two component calls at the originating and terminating Communication Manager platforms so that the call looks like a "normal" call to the end users. SBS calls will support all QSIG features currently supported by Avaya Communication Manager. SBS calls can be interworked over SBS to non-sbs networks in the same fashion that Avaya solutions currently interwork QSIG to non-qsig networks. For each SBS call, an available "SBS Extension" is used to coordinate between the signaling IP call and the circuit-switched bearer call. A sufficient pool of these extensions must be configured based on busy hour call traffic capacity. Each SBS Extension is used for a short time during the SBS call setup phase. 2

5 SBS Extensions are "virtual" extensions in that they are administered without associated hardware. Despite the absence of actual telephones, these SBS Extensions do reduce the pool of available administrable extensions on each system. Each of the SBS Extensions must be based on a real DID number leased from the local exchange company in the typical PSTN environment. Support for SBS may require additional hardware. A quantity of TN799DP C-LAN circuit packs (or equivalent support on Avaya G700 media gateways), IP Trunk port licenses, and other components may be required to implement SBS. QSIG over IP Trunks may be preferred to SBS for some implementations or some links in a QSIG network. Both IP trunking and SBS can be used in the same QSIG network. SBS is not necessarily suggested for those Avaya-enabled enterprises that already have IP trunking deployed to support DCS or QSIG networks. IP Trunks are administered as virtual connections between two IP endpoints that must be defined by IP endpoints. With IP trunking, both bearer and signaling is carried over a private WAN, rather than over a public or private network using the PSTN. Following are guidelines for Communication Manager-enabled Media Server and Media Gateway resources required to implement QSIG SBS: Every Media Server running Communication Manager in the network will require the Enhanced Networking bundle. This includes all QSIG functionality supported in Communication Manager applications. To support SBS, each node will require Communication Manager 1.3 or later software. SBS extensions are used only during call set-up for SBS calls. These extensions require DID numbers and can be pooled resources for SBS call setup. Each SBS extension requires an extension administered without hardware. Each SBS call requires an SBS trunk and a non-sbs trunk during the duration of the call. Each SBS trunk is defined as an H.323 trunk. (Note: the SBS trunks do not require hardware.) Each non-sbs trunk call uses a trunk port. The TN799DP C-LAN is required on each node for SBS calls. It is recommended that at least one C- LAN be added per node and should be dedicated to SBS calls. In some cases, more than one C-LAN may be required per node, depending on traffic requirements. The TN2302AP Media Processor circuit pack is not required for SBS calls. Sufficient trunk circuit packs are required to support the maximum number of simultaneously used bearer trunks over trunk channels. 3

6 Section 3: Primary Benefits of QSIG Separation of Bearer and Signaling 3.1: Assure Voice Quality QSIG networking is advantageous in complex networks when voice must be compressed and decompressed, or companded multiple times for codec translation, to traverse nodes, or for voice messaging storage. QSIG route optimization using path replacement and rerouting techniques can potentially reduce the number of hops required to connect a call. Possible voice quality degradation is avoided by the use of these QSIG routing techniques. It is possible to implement IP trunking between Avaya Communication Manager-enabled Media Servers and Avaya DEFINITY Servers with low latency and very good voice quality. The performance of IP trunking over the WAN or VPN depends on deployment of adequate bandwidth, a QoS policy, and the performance characteristics of the multi-services networking infrastructure that supports it. Numerous Avaya customers already have deployed DCS and QSIG networks that rely on IP trunking. Though IP and frame relay networks can be designed to reliably assure voice quality, degradation may occur when these best-effort networks are disrupted, impaired, or over-loaded. By contrast, connections over the PSTN are likely to provide toll quality voice connectivity since bandwidth is dedicated for each switched connection. When SBS is used, IP signaling connections require less bandwidth per call than IP bearer connections and are also less susceptible to latency and jitter problems. Communication Manager QSIG networks will be able to support combinations of SBS and IP Trunk links between nodes. When the PSTN is not available for some reason, IP trunking can be used as a fallback, or vice versa. 3.2: Enterprise-wide Ubiquity of Communications Avaya s active support and promotion of internationally recognized standards is a strong investment protection message to multi-location customers. For Avaya-enabled enterprises that acquire businesses that utilize other vendors communications platforms, QSIG may be the enabler for enterprise-wide communications networking. QSIG will become increasingly important for networking of converged voice over combinations of PSTN, IP, Frame Relay, and ATM networking infrastructures. These mixed networks can share Avaya voice messaging platforms. Avaya s QSIG implementation assures DCS-like functionality as well as standard QSIG features. Avaya s experience and interoperability capabilities with QSIG are well established where Avaya products have a presence. Avaya products are supported in 90 countries. Unlike DCS+ virtual networks, SBS implementations transcend the network presence of individual service providers. 3.3: Enabling "Killer Apps" Communication Manager QSIG networks enable killer apps such as unified communications, QSIG centralized attendant service, turret integration for the financial industry, centralized messaging, conferencing and collaboration across the enterprise, Internet and converged contact centers, and over 650 features that can be demonstrated to increase productivity. These are real world productivity enhancers. Unified communications reduces the time required to access multiple messaging services and can enable quicker responses to customer inquiries. QSIG centralized attendant service can reduce the number of 4

7 attendants required to answer calls or may provide a faster response to callers, while reducing network expenses through route optimization and path replacement. QSIG turret integration allows brokerages to handle calls quicker and increase the number of transactions that can be handled. Conferencing and collaboration over Communication Manager QSIG networks can reduce product development time while quality is improved. A fully-featured Internet Call Center may translate into fewer abandoned shopping carts, resulting in more sales revenue. Additionally, ISDN UUI (User to User Information) messages are often used to enable CRM (customer relationship manager) and contact center applications. The length of UUI messages is limited in some public ISDN networks. This limitation may be overcome by the use of SBS. These "killer apps" may pay for themselves in a short period of time. The full set of Communication Manager QSIG functionality is available over QSIG SBS. 3.4: Communications Continuity Single points of failure can be reduced or eliminated. Avaya communications servers and media gateways are well known for their reliability and survivability. Networks can be designed with redundant links and entry points. Distributed QSIG networks can also be designed to assure continuity s. A key to planning for business continuity is to distribute call handling across the enterprise rather than relying on a centralized hub. Communication Manager QSIG networks are well suited to distributed topologies. Communication Manager QSIG networks can be designed with a mixture of SBS and IP trunking; more than one service provider s network can be selected to provide alternate paths between locations in the event that one network should fail. This reduces dependency on a single service provider. Avaya provides products and services solutions to protect access security, as well as protection and encryption of converged telephony sessions. 3.5: Reduce Expenses The case for toll avoidance over public IP and frame relay networks is not as strong as it once was. Many large enterprises are able to obtain dial tone services over the PSTN for 3 cents (US currency) per minute or less. IP bandwidth over public WANs and VPNs is typically more expensive than bandwidth over the LAN or campus network. SBS may make sense when IP or frame relay bandwidth between nodes is expensive. The costs for network connectivity are constantly changing. The network topology can be changed accordingly. Upgrades to Communication Manager typically preserve 80% to 90% of the investment in Avaya PBXs. Least cost routing and time-of-day routing can be used to access network resources wisely. Migrating to SBS or IP trunking from a DCS or QSIG network utilizing dedicated T1, E1, or PRI links over the PSTN may result in reducing networking operating costs because bandwidth is allocated on an asneeded basis. Pooling resources via QSIG centralized attendant service, centralized voice messaging, and unified messaging can result in reduced implementation costs. QSIG networking can also facilitate cost savings by enabling outsourcing. QSIG and SBS provide feature transparency across Avaya platforms. This means the same look and feel and access to features for a globally deployed workforce. Those familiar with Avaya DEFINITY and Communication Manager, whether from the perspective of an end-user or of a system administrator, will not need to be retrained. 5

8 Migrating a network from DCS to QSIG involves provisioning, planning, project management, administration of software options and coordination. Avaya professional services resources are available to facilitate expedient migration of existing networks to expanded numbering plans and QSIG with a minimum of disruption to existing operations. Please contact Avaya or your Avaya BusinessPartner representative for further information. Section 4: Conclusion Avaya s implementation of QSIG, and particularly the QSIG Separation of Bearer from Signaling, can enable "virtual private networks" that provide enterprise-wide full scalability and feature-transparency that assure voice quality and ubiquity of service. QSIG networks are a viable option for enterprises with existing DCS or DCS+ networks, as well as new implementations that can benefit from feature-transparent networking. The advantages can be quantified in terms of productivity enhancement; the SBS feature can pay for itself because it allocates bandwidth on demand between nodes instead of requiring dedicated links. Section 5: Avaya QSIG Glossary Following is a glossary of terms used in this document. Term or Acronym Definition ATM Avaya Communication Manager BX.25 C-LAN CMS Codec Companding Asynchronous Transport Mode - a dedicated-connection switching technology that organizes digital data into 53 byte cell units and transmits them over a physical medium using digital signal technology. Individually, a cell is processed asynchronously relative to other related cells and is queued before being multiplexing over the transmission path. Highly scalable and reliable voice application software with rich call processing and contact center functions and widely accepted application-programming interface that supports a range of Avaya and third-party applications. A version of the CCITT X.25 protocol for data communications. BX.25 adds a fourth level to the standard X.25 interface. This uppermost level combines levels 4, 5, and 6 of the ISO reference model. TN799 Circuit Pack - Controlled-LAN. Provides TCP/IP connectivity over Ethernet or PPP to adjuncts. This circuit pack in a DEFINITY or MultiVantage media gateway serves as the server s network interface. It terminates IP (TCP & UDP) and relays those sockets and connections up to the DEFINITY or MultiVantage server. The C-LAN serves as an H.323 gateway. Avaya Call Management System an Avaya adjunct processor used to provide reports on contact center activity. Coder/decoder or compressor/decompressor - a hardware or software device, typically implemented in Digital Signal Processor firmware, which converts data from one format to another. A commonly used method to digitally encode sound. 6

9 Term or Acronym Definition DCS DCS+ E1 Feature Deficit G700 Media Gateway Intuity IP Trunking ISDN ISO ITU LAN LWC MWI N-Quest Octel Path Replacement Distributed Communication System an Avaya telephony capability that enables feature-trans parent networking across Avaya converged communications platforms. DCS networking capability that supports virtual feature-transparent networking. E1 (or E-1) is a European digital transmission format devised by the ITU-TS and given the name by the Conference of European Postal and Telecommunication Administration (CEPT). It s the equivalent of the North American T-carrier system format. E2 through E5 are carriers in increasing multiples of the E1 format. The E1 signal format carries data at a rate of million bits per second and can carry 32 channels of 64 Kbps each. E1 carries at a somewhat higher data rate than T-1 (which carries million bits per second) because, unlike T-1, it does not do bit-robbing and all eight bits per channel are used to code the signal. E1 and T-1 can be interconnected for international use. A term used to describe the absence of directly comparable features in one offering as compared to another. An Avaya H.248 Media Gateway that is used with Avaya S8300 and Avaya S8700 Media Servers. An Avaya voice messaging platform. Communications channels between converged communications platforms that use Internet Protocol. Integrated Services Digital Network is a network protocol based on ITU Q.931 specifications to provide intelligent networking functionality International Standards Organization International Telecommunications Union - Formerly known as International Telegraph and Telephone Consultative Committee (CCITT), ITU is an international organization that sets universal standards for data communications, including ISDN. ITU members are from telecommunications companies and organizations around the world. Local Area Network Leave Word Calling is a DEFINITY or Communication Manager message used to activate MWI lamps from a station or messaging system using a Feature Access Code Message Waiting Indication is the functionality of lighting and darkening lamps on telephones to indicate whether the user has a message. MCI/WorldCom features for provision of User-to-User Services. Needed to transport DCS+ messages in the MCI/WorldCom PSTN The name of the voice messaging products company (and its products) acquired by Lucent, which later became part of Avaya. A method used to minimize the number of links in a communications session involving more than two nodes. 7

10 Term or Acronym Definition PRI PSTN QSIG Rerouting RNX Avaya S8300 Media Server Avaya S8700 Media Server SBS SDN Shuffling T1 TDM TSC Avaya Unified Messaging, Unified Communications Primary Rate Interface - A standard ISDN frame format that specifies the protocol used between two or more communications systems. PRI runs at Mbps and, as used in North America, provides kbps B-channels (voice or data) and one 64-kbps D-channel (signaling). The D- channel is the 24th channel of the interface and contains multiplexed signaling information for the other 23 channels. Public Switched Telecommunications Network Standards based multi-vendor private networking protocol based on IQ.931 standards (ISDN) A method used to minimize the number of links in a communications session involving more than two nodes. Route-number index a private network office code used to designate nodes. An Avaya media server, which can be used with G700 Media Gateways. The Avaya line of media servers provides a robust application platform based on industry standard operating systems to support distributed IP networking and centralized call processing across multi-protocol networks An Avaya media server provided in pairs, which support Avaya G600, G700, MCC1, and SCC1 media gateways. The Avaya line of media servers provides a robust application platform based on industry standard operating systems to support distributed IP networking and centralized call processing across multi-protocol networks. Separation of Bearer from Signaling the separation of the QSIG signaling channel and the QSIG communications payload channel to provide a low cost "virtual private network" with high voice quality. Software Defined Network -Trade name of AT&T for ISDN Software Defined Network, a VPN offering that is needed to support DCS+ virtual networks. Avaya MultiVantage Communications Applications provide IP to IP direct audio connections to save system resources, such as channels on the media processor and TDM bus time slots, and to improve voice quality by eliminating extra coder/decoder functions on the media processor. This is sometimes called "shuffling." The end user does not have to take any action to invoke audio shuffling. The gateway will shuffle, if possible, after a point-to-point call is established between two endpoints, provided both endpoints are capable of handling shuffling. The T1 (or T-1) carrier is a commonly used digital line in the United States, Canada, and Japan. In these countries, it carries 24 pulse code modulation (pulse code modulation) signals using Time-Division Multiplexing at an overall rate of megabits per second. Time-Division Multiplexing - Multiplexing that divides a transmission channel into successive time slots. Temporary Signaling Connection an ISDN User-to-User message type for exchanging call associated and non-call associated messages. Used by DEFINITY and MultiVantage Software to transport DCS+ messages in the ISDN PRI protocol. An Avaya platform that lets users send, receive and manage all , voice and fax messages from any telephone, PC or information device. 8

11 Term or Acronym Virtual Private Network (VPN) WAN Definition In the context of this document, this means emulating feature rich private voice networks while using the PSTN for transport. A virtual private network (VPN) is a private data network that makes use of the public telecommunication infrastructure, maintaining privacy through the use of a tunneling protocol and security procedures. A virtual private network can be contrasted with a system of owned or leased lines that can only be used by one organization. The concept of the VPN is to give the entity the same capabilities at much lower cost by using the shared public infrastructure rather than a private one. Network providers have provided secure shared resources for voice messages. A virtual private network makes it possible to have the same secure sharing of public resources for data. Enterprises today can using a Virtual Private Network for both extranet and wide-area intranet. Using a virtual private network involves encrypting data before sending it through the public network and decrypting it at the receiving end. An additional level of security involves encrypting not only the data but also the originating and receiving network addresses. VPN software is typically installed as part of a company s fire wall server. Wide Area Network a network distributed over a large geographic area. 9

12 About Avaya Avaya enables businesses to achieve superior results by designing, building and managing their communications networks. Over one million businesses worldwide, including more than 90 percent of the FORTUNE 500, rely on Avaya solutions and services to enhance value, improve productivity and gain competitive advantage. Focused on enterprises large to small, Avaya is a world leader in secure and reliable IP telephony systems, communications software applications and full life-cycle services. Driving the convergence of voice and data communications with business applications and distinguished by comprehensive worldwide services Avaya helps customers leverage existing and new networks to unlock value and enhance business performance. reach IP Telephony Contact Centers Unified Communication Services 2003 Avaya Inc. All Rights Reserved. Avaya and the Avaya Logo are trademarks of Avaya Inc. and may be registered in certain jurisdictions. All trademarks identified by the, SM or TM are registered trademarks, service marks or trademarks, respectively, of Avaya Inc. All other trademarks are the property of their respective owners. Printed in the U.S.A. 04/03 EF-LB2056 avaya.com