Working on Ol' Reliable

Use Internet techniques such as data caching and firewalls to address network-reliability concerns caused by subscriber growth, WNP and convergence.

Has it been taking longer for your customers' wire-less calls to get through? Are they getting an all-circuits-busy message when trying to place a call or hearing that fast busy signal a little more often these days? Unfortunately, these annoyances are likely to get worse before they get better unless you take the appropriate measures.

The explosive growth of the wireless subscriber base, new service-delivery pressures and increased carrier-to-carrier interconnection have significantly increased SS7 message load on the WIN - resulting in increased call-setup times and reduced quality of service (QoS). In light of current market conditions, carriers already are wondering how much more the WIN can take before it reaches its breaking point. And these concerns are further exacerbated with wireless number portability (WNP) (expected to further increase network traffic by up to 40%) and true voice/data convergence quickly approaching.

Of course, with network convergence on the horizon, carriers don't want to build out their networks to support increasing voice traffic. But they don't want to run the risk of letting it tear down their network either. Therefore, many carriers are looking for ways to offload the signaling traffic bogging down their WIN so they can focus on higher-value initiatives such as wireless Inter-net and 3G.

To address these challenges, some carriers are adopting technologies based on successful Internet paradigms.

Traffic Increases Not too long ago, the data-networking industry faced similar challenges. Before at-home Internet service became as popular as cable TV, it was government controlled, interconnecting only a handful of federal agencies. Today the Internet is vastly interconnected, enabling tens of millions of people to get online every day. The WIN has followed a similar evolution path. Before deregulation, the telephone industry operated in a virtual monopoly with only a select group of incumbent carriers interconnecting to one another. Today, the telephone network interconnects thousands of carriers, and wireless technology is used by millions of Americans.

Similarly, both computer networks and the WIN were designed in an era of limited competition and service offerings. The architecture consisted of monolithic mainframe databases and proprietary networking devices. Design limitations of these proprietary systems quickly became a hindrance to the growth of the Internet. And today, information buried in large mainframe databases deep in the core of the WIN is preventing carriers from keeping up with rapid market changes and ensuring the reliability of their networks.

To deal with the exponential rise of World-Wide-Web-related traffic, data-networking companies brought intelligence from the core to the edge of the network through the development of data caching and firewall techniques. This enabled ISPs to deliver information in a timely and secure fashion, effectively eliminating the world-wide wait.

Concerns posed by the exponential rise of WIN traffic and a more open environment can be managed using similar strategies. As shown in Table 1 on page 44, by using the caching technique to manage the expected 40% increase of WNP-related traffic, carriers could reduce the expected number of dips by up to 90%. Carriers also can ensure the reliability of their networks using a signaling firewall to protect against unproven technologies, inexperienced providers and invasive attacks.

WNP Looming As mentioned, carrier' networks already are overloaded due to high subscriber growth, an increase in interconnect agreements and new service-delivery pressures. Now carriers must find a way to meet the FCC WNP mandate by November 2002. To meet this deadline, they will be spending a lot of time and money.

In the Internet world, vendors developed the data-caching technique to deal with high-traffic volumes. Caching is a special, high-speed mechanism for storing frequently requested information in memory (often referred to as the cache) located near the origination point of the request. Before an information request is sent out to the network, the cache database is first checked to see if the information resides locally. If it does, the cache database responds back to the requester with the information, eliminating the need for the query to traverse the network. This technique enables ISPs to store frequently requested data locally at the requester's terminal to help reduce costs, improve response time and optimize network usage.

For carriers, applying this same technique is an easy way to offset WNP-related costs and still meet the FCC deadline. WNP caching could eliminate the need for repeated WNP dips, improve call-setup times and enable carriers to focus their resources on higher-value activities. It also could reduce network build-out requirements by eliminating the need to deploy additional costly telephony equipment including signal transfer points, service control points (SCPs) and SS7 links.

A WNP cache system would store WNP records near the MSC on its SS7 links. Each time a WNP query is launched by the MSC, the cache system would determine whether to pass the request to the WNP database or retrieve the information from its local cache database. If it finds the record within its cache database, the system would generate a response telling the service switching functions it located the data - eliminating the need to query the number-portability database.

By eliminating the need for repeated WNP queries, wireless carriers can redirect capital allocated for WNP to more valuable business initiatives such as 3G and wireless Internet.

WNP cache systems also help carriers enhance QoS through improved call-setup times. Currently it easily can take up to 15 seconds for a wireless caller to reach his party during peak busy hours. The roll-out of WNP will result in even longer call-setup times. But with a WNP caching system, carriers can significantly reduce the WIN call load for faster call-setup times that will help ensure the customer has a positive experience every time he picks up the phone.

Threats to Reliability Reliability is the hallmark of the U.S. telecom industry, however, it is being challenged by necessary business restructuring. Deregulation has removed a key barrier to market entry, and network convergence holds the promise of wireless services once unimaginable. These exciting changes, however, pose reliability concerns. Interconnect partners and true voice/data convergence via gateways expose the network to unproven technologies, inexperienced providers and impending invasive attacks.

Threats posed by untested infrastructure and unmonitored interconnection points jeopardize the WIN's reliability. Perhaps, a less-predictable and farther-reaching reliability problem is system failure arising from increases in the volume and complexity of interconnection as well as the introduction of new technologies. Competition has created the potential for millions of new interconnection points without any increase in capacity or redundancy in the network. The complexity of new networks and technologies almost certainly will swell the WIN to such magnitudes that a system failure undoubtedly will occur. And there is no assurance that a failure will be localized to one network since interconnection has forfeited this scenario.

Also, ISPs interfacing with the WIN further increase the complexity of the public network - bringing arguably the biggest network-reliability concern - IP network interconnection. Other issues include signaling links being made available to private organizations supporting private SCPs, since little reliance can be placed on signals generated by this equipment.

In the Internet environment, ISPs address heightened network-security concerns caused by increased interconnection by developing and deploying firewalls. These systems are designed to ensure system reliability by protecting both the network and its elements from fraudulent and malicious activity. A firewall has the ability to examine every message entering and leaving the network and pass, alert on, and/or block harmful activity. Firewalls can control fraudulent activities, mitigate threats from hackers and provide added visibility into network operations.

Enforcing Interconnection Agreements A signaling firewall would give carriers the network-wide visibility and control needed to enforce interconnect agreements and securely converge their voice/data networks. With a signaling firewall, carriers could examine every message and (based on their operations policy) inspect, block, reroute or pass traffic. A signaling firewall could provide message discrimination beyond the capabilities of gateway screening to a more granular level using custom criteria such as time of day, day of week, source, destination, message type, etc.

Through the examination of messages, parameters and primitives, carriers could prevent unauthorized use of the WIN and enforce interconnect agreements. And since the signaling firewall would rely on SS7 and not specific vendor equipment, it could protect any SS7-enabled device regardless of vendor type. This type of system would provide network-usage data and other relevant statistics used to make educated decisions on how to improve network efficiency and reliability. Furthermore, co-locating network-visibility features on the same platform as an active control capability is not only cost effective, it could have a profound impact on the next-generation signaling network.

Wireless network and management resources are scarce, and market conditions continue to stress the WIN. Using successful Internet paradigms to address network-reliability concerns posed by rapid subscriber growth, WNP and convergence is an easy, low-cost way for carriers to keep up with market changes. WNP caching can significantly reduce the message load bogging down the network, and help carriers meet the FCC's deadline without huge WNP implementation and support expenses.

Deploying a signaling firewall also will help carriers ensure the reliability of their networks, which currently are being threatened by high traffic volumes, hackers, inexperienced providers and unproven technologies. With this technology, carriers can continue to enjoy high network reliability despite the risks associated with voice/data convergence.

The 1996 Telecommunications Act only required LECs to offer LNP, however, the mandate was later expanded to include wireless. Wireless number portability (WNP) initially was scheduled for March 2000, however, the FCC recently postponed the roll-out until November 2002. This mandate will allow wireless customers to change carriers and/or service type without changing their telephone numbers. Carriers routing telephone calls to end users that have "ported" their telephone numbers from one carrier to another must perform a database query to a number-portability database to obtain the location routing number (LRN) corresponding to the dialed party. The database query is performed for all calls where the NPA-NXX of the called number has been marked in the switching tables as portable. The carrier then would route the call to the new switch destination based on the LRN. Figure 1 on page 44 shows network architecture performing WNP functionality using a service control point number-portability database.