The telecommunications industry is experiencing a historic change. Today's network service providers are in a fiercely competitive market. They continue to face the challenge of new service definition and delivery, while competitors offer the same services at attractive prices. Service providers need to differentiate themselves from competitors by offering value-added services in addition to traditional voice services and data applications. With deregulation creating opportunities for competition, service providers must be able to rapidly develop and deploy new services to differentiate themselves from their competition and create new revenue streams.
The Cisco SC 2200 Signaling Controller, a key component in several Cisco packet telephony solutions, unlocks the potential for competitive differentiation among service providers. Already a widely used method of providing centralized functions for adding Common Channel Signaling System 7 (SS7/C7) interfaces to large remote access points of presence (POPs), its latest release provides carrier-grade reliability through a redundant architecture and improves call processing and usability.
The Cisco SC 2200 is a software application that runs on industry-standard Sun UNIX platforms. Specifically designed to meet stringent telco requirements, the Cisco SC 2200 provides a cost-effective solution for integrating high-growth dial access and H.323- and Session Initiation Protocol (SIP)-enabled voice over IP (VoIP) into the public network infrastructure. The Cisco SC 2200 solves many of the issues surrounding a conventional Primary Rate Interface (PRI) service offering, such as high interconnect costs and congestion from ever-growing Internet traffic. The Cisco SC 2200 allows service providers to realize new revenue opportunities, reduce operating costs, and cost-effectively scale their networks.
Working with Cisco AS5000 series access servers and voice gateways, the Cisco SC 2200 creates a node that, from a signaling perspective, functions as a terminating and originating end office with SS7/C7. The Cisco SC 2200 is a key enabler of next generation network architecture.
The Cisco SC 2200 is a flexible software product that is provisioned based on the SS7/C7 variant required by the customer-specific application, such as Integrated Services Digital Network User Part (ISUP), National User Part (NUP), or Telephony User Part (TUP). The Cisco SC 2200 currently supports more than 40 variants of SS7/C7 for 40 countries, with more continually added. The flexibility of the Cisco SC 2200 is enabled by its Message Definition Language (MDL), an object-oriented programming language specifically designed for creating new signaling protocols. With MDL, Cisco can rapidly develop, test, and customize to any national variant of SS7/C7.
The Cisco SC 2200 is carrier-grade and central-office ready. The Cisco SC 2200 software runs on Sun Netra t 1400 and Netra t 1405, Netra 1200 and Netra t 1205, and Netra t 100 and Netra t 105 host platforms. These central-office grade platforms are rack-mountable and Network Equipment Building Systems (NEBS) Level 3 certified, and they meet safety and homologation requirements for worldwide deployment. With the Cisco continuous service architecture, hosts are deployed in active and standby pairs. The Cisco SC 2200 software passes checkpoint information between the active and standby server, fully preserving active calls in the event of a failover. These carrier-grade servers, along with continuous-service software design, enable carrier-class availability in excess of 99.999 percent.
For most providers of remote access and VoIP services today, ISDN PRI is the most commonly used method of connecting to the Public Switched Telephone Network (PSTN). Fueled by the growth of the Internet and the need for new services, the demand for ISDN PRI has experienced an unprecedented increase since 1998. Although the tariffed rates for ISDN PRI have continued to fall because of competitive pressures. ISDN PRI still represents the most significant cost item for many service providers.
The Cisco SC 2200 offers an alternative for service providers who are looking to reduce their PSTN connectivity charges. Whether seen as lower tariffs or reduced capital investment, the cost savings enabled by the Cisco SC 2200 translates into higher profitability.
The Cisco SC 2200 introduces the power and dependability of the SS7/C7 signaling network, allowing customers to interconnect to the PSTN using intermachine-trunks, or IMTs. The benefits of using IMTs include:
- Direct peer-to-peer connection to the PSTN eliminates the need to invest in additional switches.
- The offload of Internet traffic from time-division multiplexing (TDM) switches and trunks brings the IP network closer to the user and relieves PSTN congestion.
- IMTs offer a favorable tariff structure; they cost significantly less than PRIs (both nonrecurring and recurring monthly charges).
- IMTs are available; PRI installation intervals are generally longer than IMTs and in many countries PRIs are not available.
- Resilient signaling utilizes the power and reliability of the highly redundant SS7/C7 network.
- With ingress and egress protocol separation, IMTs remove the requirement for the end office to convert signaling to PRI.
The Cisco SC 2200 brings SS7/C7-based access solutions that provide significant infrastructure cost savings over those using PRIs. This creates an environment that improves competitiveness and reduces operational costs.
The Cisco SC 2200 is a key component of the Cisco Global Long Distance solution and the Cisco Wholesale Dial solution. In the Cisco Wholesale Dial solution, the SC 2200 enables SS7 Interconnect for Access Servers and in the Cisco Global Long Distance solution it enables SS7 Interconnect for Voice Gateways—a H.323-based VoIP capability.
Carriers are interested in new revenue generation and capital investment reduction. Driven by the new business model of wholesale services for the retail Internet service provider (ISP), service providers require SS7/C7 interconnect as part of a complete wholesale dial solution to reduce overall operational costs and scale to million-port networks.
As consumer demand for dial access to the Internet increases, carriers worldwide are implementing wholesale dial access services. Competitive carriers are interested in offering Internet access services without deploying additional circuit switches. To slash costs, carriers need SS7/C7 interconnection to the PSTN in order to take advantage of better tariffs or revenue sharing. With SS7/C7, thousands of calls are signaled over the same circuits, as opposed to dozens with PRI/channel associated signaling (CAS). This new level of dial scalability is part of the Cisco Wholesale Dial solution (Figure 1).
Cisco Wholesale Dial Architecture
In many cases, service providers, whether installing new or operating existing H.323 Media Gateway Control Protocol (MGCP) and Session Initiation Protocol (SIP) networks, are restricted to using expensive and sometimes unavailable PRIs. The Cisco SS7 Interconnect for Voice Gateways solution allows these customers to interconnect to PSTN networks, avoiding costly PRIs. Service providers will use this solution to eliminate unnecessary paths through TDM switches. Figure 2 shows the role of the Cisco SC 2200 in this solution.
SS7 Interconnect for Voice Gateways
The Cisco SC 2200 Signaling Controller maintains an internal mapping of bearer circuits on the PSTN side to those on the gateways to enable SS7/C7 interconnection, while providing necessary carrier functions such as alarms, statistics, and Call Detail Records (CDRs) for billing. As the key component to the solutions described above, high availability is absolutely critical to ensure nonstop operation. To achieve this level of performance, Cisco created the continuous service node.
Figure 3 shows the continuous-service node architecture, which consists of redundant Sun hosts, the Cisco SC 2200 software, and redundant Cisco Signaling Link Terminals (SLTs). The redundant hosts and SLTs communicate through a dedicated signaling control IP network. The CiscoMedia Gateway Controller (MGC) Node Manager provides a single interface for fault, configuration, and performance management for all network elements within the Cisco SC 2200 node.
Cisco SC 2200 Node Architecture
Maintaining the SS7/C7 signaling links is critical to being part of the SS7/C7 network. SS7/C7 "A" or "F" links from the PSTN terminate on the SLTs. The SLTs handle processor-intensive message transfer part (MTP) Layers 1 and 2 of the SS7/C7 stack, then encapsulate MTP3 and above layers in Reliable User Datagram Protocol (RUDP) and forward to both the active and standby hosts. The Session Manager Protocol maintains the IP link between the SLT and the hosts, maintaining the integrity of the signaling links. The single-purpose, Cisco IOS® Software-based SLT software operates on the widely deployed NEBS-compliant Cisco 2611 Multiservice Access Router platform. The dual-port drop-and-insert capability of the Cisco SLT grooms bearers and F-link signaling traffic when fully associated mode signaling is used. This avoids the expense of additional M1/0 multiplexing when using F links, further lowering costs. Two links are terminated per SLT. Link sets are terminated across multiple SLTs to eliminate single points of failure.
Software fault tolerance and redundant operation are achieved by passing checkpoint call-context information between the active and standby host. This process, as well as main memory database synchronization, enables switchover from active to standby host with no disruption of active calls.
The solution uses extended Q.931 over IP to provide call control, continuity test (COT), and maintenance functions. For added resiliency, the redundant link manager (RLM) is unique to the Cisco solution. The RLM allows for multiple, redundant IP paths to be treated as one path by upper layers. The design is optimized for message-based transmissions over redundant links. The instant recovery of RLM ensures connectivity from Cisco SC 2200s to gateways.
The Cisco MGC Node Manager (MNM) is the element management system (EMS) for the components that comprise the Cisco SC 2200 node. The Cisco MGC Node Manager is built on the Cisco Element Management Framework (EMF), a carrier-class network management structure. This framework was designed specifically to address the challenges of developing and deploying robust, large-scale, multivendor, multitechnology management solutions.
Cisco SC 2200 Node Hardware Components
Signaling Controller Service Features
The breadth and depth of the Cisco access to resources, shared intellectual capital, and leading data and telecommunications products and expertise is unmatched in the industry. This combination enables Cisco to provide the highest quality available in carrier-class support, solutions, and vision for service providers. Cisco service and support solutions enhance the value of your investment in network infrastructure, resulting in an overall reduced cost of doing business. This service and support for the Cisco SC 2200 includes installation, maintenance, and upgrade plans and a full range of professional services to cover all aspects of design and implementation. Now you can fully deliver on the promise of internetworking technology with the backing of world-class support and service.
For more information, go to http://www.cisco.com/warp/public/cc/serv/mkt/sup/sp/.
Sun Server Configurations and Specifics
Sun Netra t Platform Specifications
Refer to the Cisco SLT Data Sheet and Q&A for specifics on the SLT: http://www.cisco.com/warp/public/cc/pd/ga/sc/prodlit/index.shtml.