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Networking's packet-packed future.

Packet over SONET grabs the spotlight as a solo performer.

With IP over SONET's emergence as a competent dance partner for--and competitor with--ATM in the backbone, information gets to experience a sort of "Dance of the Protocols" in the Netcracker Suite. It's interesting to watch the pair mix, while each also tries to show off individual moves and talents.

ATM flaunts a certain amount of maturity onstage, an ability to perform well with multiple partners (voice, data, and video), and quality-of-service (QoS) delivery. But the ATM dance (although we are talking backbone speeds that outpace spins and leaps by light-years) is not without its latency-plagued missteps. The central problem is in transferring Internet protocol (IP) traffic (or any other frame-based protocol) to ATM cells and then back. Those two steps of conversion result in wasted bandwidth when compared to pure IP throughout the entire transfer.


"When you try to marry ATM and IP, you've got some troubles," says Yuval Boger, VP business development at RADCOM Ltd. This inefficiency is often referred to as the "cell tax," which is the overhead of various ATM layers that have to be converted. Inefficiency equals wasted bandwidth. And wasted bandwidth equals lost profits.

Boger gives this example: "Let's say a typical IP packet for Internet browsing is around 576 bytes. If you transfer this over ATM on an OC-3 link, you are going to be able to use less than 80% (actually 79.6%) of your bandwidth for the actual IP transfer. The other 20% is overhead--ATM overhead or SONET overhead. Now, if you take the same packet and put it over Packet over SONET (POS) technology, you find that you get 95.4% efficiency. So, over 95% of your bandwidth can be used for IP, and that's a big savings."


As large enterprises, and ISPs especially, begin to deploy PoS in their backbones, the technology is not shy about showing off its best moves.

"What I'm seeing is that many major ISPs either are using PoS today or they are moving their backbones to POS," says Boger. "And this is Sprint, IBM, UUNET, and others. A lot of ISPs are saying PoS is the way to go."

"Due to greater payload efficiencies, acceptance of Packet over SONET technology is booming," says Bruce Bowers, software development test engineer, optical internetworking business unit, Cisco Systems.

It makes sense, for example, if you're an IS P delivering predominantly IP traffic (Internet browsing) that you would stick with IP from end to end. And ISPs especially may not need all of the advantages that ATM currently has for carrying voice.

There is another difference between PoS and ATM, and it is one of complexity. When you're working with PoS, you' re potentially using all of the same protocols that you used when you were just using IProuting. All the routing protocols in the IP suite carry over to PoS. In contrast, bringing ATM into the show requires a whole set of new controls for ATM that need to be dealt with and managed.

"It is a very attractive proposition for an ISP to see end-to-end frames--not having to translate into any cells in the middle--and getting more efficient transfer," says Boger. "And since it is also a simpler technology, it will probably turn out to be cheaper.

There are critics in the audience (there always are), but PoS can provide a markedly more efficient way of carrying certain types of traffic. One way to actually "see" the effectiveness of PoS and to maximize bandwidth use over large networks is through testing.


RADCOM just announced in January its new one-of-a-kind WireSpeed 622 Packet over SONET Analyzer. The device, which can also test ATM networks and over 300 protocols to boot, can act as an impartial protocol "dance" judge for ISPs and enterprises interested in analyzing the cutting edge of high-speed data networking.

"There are a lot of good ATM analyzers out there," says Boger, "but, until now, mere was no PoS analyzer out there. That's where we come in."

The WireSpeed PoS Analyzer provides complete diagnostics at 622 Mbps data rates for installation, management, and maintenance of high-speed PoS/SDH networks. The analyzer is also used by equipment manufacturers to assist in the development of PoS devices.

"I think that the piece of equipment that is most sold today for PoS is a big router that Cisco makes called the 12000 Gigabit Switch Router," says Bogen "Cisco has recently reported that they have sold over a thousand of these units." And networks using this type of router need to monitored accurately and managed effectively.

"We have been working with PoS interfaces in our lab for several years, and it has always been frustrating not having a tool to directly verify what the packets look like going out the fiber," says Bowers. "Now, at rates up to OC-12, we can reliably monitor Layer 2 encapsulations, as well as Layer 3 and up packet headers and contents. The RADCOM protocol analyzer has also been very useful in generating OC-12 fiber-rate traffic."


Beyond backbone applications, Boger says that he is seeing a lot of start-up companies who are beginning to develop access products at 155 Mbps. They are trying to provide higher-speed access ramps, for example, for enterprises who use Frame Relay and are looking for a next-step migration solution from their current T1 or sub-T1 bandwidth crunches. It would be logical for such companies to keep in step with a perfect partner, namely, by accessing an uplink of 155 Mbps to connect to ISPs who are already running PoS networks.

Circle 277 for more information from RADCOM
COPYRIGHT 1999 Nelson Publishing
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Copyright 1999 Gale, Cengage Learning. All rights reserved.

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Title Annotation:News Briefs
Author:Foley, Mike
Publication:Communications News
Date:May 1, 1999
Previous Article:Bubble, bubble, less toil and trouble.
Next Article:Sometimes the grass is greener.

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