Strategic Planning By David Hanson

The Weak Link Public network reliability has become a mandatory issue. In the second quarter of 199f alone, there were 331 switch-related outages, which affected more fhan 3.5 million phone lines and lasted an average of 45 minutes each. The carriers are trying but fhey still represent the ‘Weak Link’ in data and voice communications. There will be improvements but wlll they be enough?

I n networks today, we’re seeing a lot of local area network functionality, dif- ferent kinds of LANs, tok-

en-ring networks with PCs, as well as Ethernet networks in the minicomputer environ- ment. We‘ve also started to see much more advanced com- munications between minicom- puters or gateway processors and the mainframe. In addition, some redundancy is starting to be built in, as well as a voice- processing capability, whether it’s on the PBX or the Central Office switch.

In many ways, networks are growing more simple as the decade progresses, through the consolidation of facilities. We just don’t have the networking staff to handle complex net- works. Therefore, we have to install extremely durable facili- ties. Fiber-optic LANs, for

David Hanson is Communications Special- ist at a leeding New York Financial Institution and will be a regular contribu- tor to the International Journal of Net- work Management.

example, have high perform- ance built into them so that you don‘t have to worry about that LAN going down, or not being able to meet your needs over the next couple of years.

Many people are advocating the phone companies and the value-added networks, and the systems integrators. The reality is that with the sophistication required in the WAN in the 1990s in order to link LANs and support the rest of the information infrastructure, we will all be hard pressed to find the resources to support the complexity of the wide-area scheme. Information access is a wonderful thing, but there are numerous drawbacks, includ- ing complex applications, data

integrity, performance, secur- ity, ease of use, new and old hardwardsoftware, staff expert- ise, a id the telephone company.

The telephone company? Is that a drawback? One of the key strategic issues when deciding for or against different methods of network implementation is Public versus Private. The com- mon wisdom is that we will have private portions in our WANs but that there will be increasing reliance on ‘the pub- lic portions. The difficulty here is that both public and private networks rely on the carriers for the transmission medium.

So, what has been happening to these camers? The futurists are seeing global fiberization, the conversion from a copper-

nformation access is a wonderful thing, but there are I numerous drawbacks, including complex applications, data integrity, performance, security, ease of use, new and old hardwardsoftware, staff experthe, and the telephone company.

102 DECEMBER 1991

based transport network to a fiber-based one, far off in the speculative future. But fiberiz- ation is happening today, and it has the ability to change the very essence of the way we do business in the world. Some are asking the question, why is i t taking so long? One key reason, and there are others, is that, for total fiberization to be viable we need to solve a few remaining technical problems like: insur- ing a reliable power source for electronic components in the network; and, even more mun- dane but no less cogent, how to guarantee the integrity of the transmission path when a major fiber trunk is accidentally cut.

Natural disasters can cripple cities, and there isn't much humans can do to prevent it. A fiber-optic cable break can have nearly the same effect. Think about what happened as a result of AT&T's cable break near New York City on 4 January 1991. An AT&T employee, pull- ing old telephone cable from a manhole in Newark NJ, some- how included the fiber in a group of cables he was cutting and disrupted 1.7 gigabits of communications traffic. Flights at the three major New York airports were either delayed or cancelled, because outside radar facilities could not make contact with the airport control towers. Bank networks were crippled, commodities exchanges were forced to close for several hours and 60% of all long-distance calls in the area were blocked. Users were shocked and angry as they struggled to determine how one cut cable could cripple business across the entire city. The anger was heightened by memories of a nationwide ser-

vice disruption due to a software glitch in January 1989 and a central office fire in 1988.

Optical fiber, although being a thin strand of brittle glass, will not break easily, even if it is mishandled. When that fiber is cut, however, users have the right to ask: Can't fiber circuits be backed up? Certainly, the primary trunk lines of the major carriers should have been backed up long ago.

The question boils down to this. Do we really understand the way the carriers switch traffic? Are we really educated consumers? For example, the Inter-exchange Carriers (IXCs) like AT&T have POPs or 'Points of Presence'. The Local Exchange Carriers (LECs) like New York Telephone have Cen- tral Offices (COs). Many com- panies think that they have routing diversity and therefore immunity from disaster if they connect to two POPs and two Central Offices. That is not always the case. A POP is not necessarily a switching center. It is usually nothing more than a hard-wired transfer point, really just a large Main Distri- bution Frame (MDF). Some- times a carrier will have multiple POPs in the same building. Also, there are differ- ent kinds of POPs: Facilities POP, Service Mode POP and matching POP. A connection may transverse one or more of these entities and we may have more POPs involved in a con- nection than we think. Maybe we should be thinking of VSATs!

Multiple POPs feeding a sin- gle trunk group are still a single point of failure. Sometimes the POPs are so situated that they

can't dynamically change the routing. In that respect, COs may be more robust in this capability to diversify or change the routing.

AT&T is not alone. US Sprint reported smaller-scale disrup- tions following two accidental cable cuts in early 1991. These actions taken together are prompting an increasing num- ber of users to reduce their dependence on a single pro- vider and spread their long- distance traffic over two or more carriers. Some of the major banks, for example, had backup with all three major carriers and were able to go to their alternate lines. However, as we have seen, if all IXCs suffer from the same malady, then, single- or multiple-vendor scenario, the result can still be havoc.

s the tally of A debilitating outages grows, carriers are scrambling to implement new technologies to protect users from network failures.

So, as the tally of debilitating outages grows, carriers are scrambling to implement new technologies to protect users from network failures. New Digital Access Cross Connect Systems (DACCS) and advanced call routing systems will hopefully facilitate routing private line and switched traffic around outages. But there may still be complications as the US Federal Communications Com- mission (FCC) is stepping up its efforts to force the nation's

Bell telephone companies to allow outside communications companies freer access to their communications networks. In the process of making the net- work as open, dynamic and responsive as possible is the FCC opening up a Pandora's box of new troubles?

Hopefully, everybody has learned their lessons. The users need to diversify and the car- riers have to plug the holes and train their personnel better to avoid preventable accidents.

The question remains whether all the carriers will redesign their networks to prevent a similar occurrence in the future. The cut cable was only one of four primary routes between New York and Newark and should not have been as disrup- tive as it was (100 000 telephone circuits were knocked out, amounting to 60% of AT&T telephone traffic into and out of New York City).

There will be improvements but it is not enough to be

reassured that the problem won't happen in the future.

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