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To: Immi who wrote (450)	11/5/1997 1:03:00 PM
From: Maverick	Respond to of 1629

Frame relay switch and FRAD vendors are adding proprietary quality of service to their boxes. Here's help sorting through the hardware By Kathleen Cholewka of Data Comm Frame relay is simple-as long as net managers don't expect it to do more than data. Ask it to deal with voice and video, though, and things are going to get a bit more complicated. Frame relay's approach to quality of service (QOS) is rudimentary at best; there's simply no way to assign priorities to different types of traffic. Don't expect much help from the Frame Relay Forum. It says it's studying the QOS conundrum, but it's main thrust is on guaranteeing service at the carrier switch. When it comes to FRADs (frame relay access devices) and CPE (customer premises equipment), net managers have to count on the vendors. They've got plenty to count on: At least 22 frame relay vendors say they can bolt on the QOS that wasn't built in. Seven sell QOS-capable frame switches-although there are some surprising MIAs. Some big switch suppliers like Newbridge Networks Inc. (Kanata, Ontario) and General Datacomm Inc. (Middlebury, Conn.) say QOS is best left to FRADs. Fifteen vendors are peddling QOS FRADs. And several sell both types of gear. Bear in mind that all of these schemes are proprietary. That means net managers are almost always forced into single-vendor solutions. And making sense of what's on the market means doing some homework. For starters, dig into how many levels of service are allowed. Then consider how these levels are provisioned-per PVC (permanent virtual circuit), SVC (switched virtual circuit), protocol, port, or IP address. Does the box slice and dice frames into uniform sizes and can it meter port speeds? How much buffering is built in? If voice is a choice, what compression algorithms are supported? Can PVCs, ports, CIRs (committed information rates), and compression be configured on the fly? Don't forget management and backup-along with basics like speeds and feeds. And be sure to get a price quote on the basic box. Congestion Questions Before sweating the details, though, net managers may want to step back and look at the big picture. Some vendors argue that there's no point in buying priority-enabled FRADs and attaching them to public frame relay networks. "It doesn't matter how many levels of priority are applied. If the public network is congested; there's still no guarantee how or when traffic will get delivered",

To: Immi who wrote (450)	11/5/1997 1:06:00 PM
From: Maverick	Respond to of 1629

Bolt on QoS, Part II says Druce MacFarlane, director of technology for the WAN business unit at Network General Corp. (Menlo Park, Calif.). "It is better than nothing," counters Paul Wallner, vice president of marketing at Hypercom Inc. (Phoenix). "Congestion on the public network can impact the delivery of frame traffic no matter what parameters you have set up, but with some quality of service on the FRAD, you have a better chance." What's more, the Frame Relay Forum argues that even though its standard doesn't specifically define QOS, there are still some basic parameters net managers can monkey with to set simple service levels. "Quality of service with a small 'q' has always been available," says Larry Greenstein, the forum's vice president of technology. Trouble is, coming up with the right port speeds and CIRs involves a lot of guesswork. On the Level Net managers who are more comfortable with gear than guessing games should start by counting up the service levels a QOS-capable FRAD or switch can accommodate. Seven vendors, including Hughes Network Systems Inc. (Germantown, Md.) and Northern Telecom Ltd. (Mississauga, Ontario), deliver three levels (see Table 1). Eight vendors, including Alcatel Data Networks (Reston, Va.) and IBM, can cope with four. RAD Data Communications Inc. (Mahwah, N.J.) offers seven; Ascom Timeplex Inc. (Woodcliff Lake, N.J.) has eight. And Netlink Inc. (Framingham, Mass.) has 16. When it comes to levels, some vendors argue that more is better. "Net managers get the flexibility to provision traffic to more than the usual high, medium, and low levels," says Bob MacGuire, Ascom Timeplex's vice president of marketing. "You may not have the need for that many levels, but they're there if you do," adds Roger Walton, product manager at Netlink. But Rick O'Dea, product line manager at Micom Communications Corp. (Simi Valley, Calif.), disagrees. "Three or four levels of service are enough." Some QOS-capable gear lets net managers reserve bandwidth on the PVC. For example, video traffic from a video codec could be allotted 40 percent of the bandwidth over a specific circuit, while the data already traveling over that circuit would take up the remaining 60 percent. More important is how the box assigns service levels. Forteen

To: Immi who wrote (450)	11/5/1997 1:09:00 PM
From: Maverick	Respond to of 1629

Bolt on QoS, Part III vendors-including Ascend Communications Inc. (Alameda, Calif.) and Motorola Information Systems Group (Mansfield, Mass.)-implement it on a per-PVC basis. That means each connection gets its own level of priority and its own CIR. A PVC carrying voice calls, for example, would be sent out onto the network first. A PVC carrying IP file transfers would be sent out after that. This approach, however, eliminates one of the biggest factors in frame relay's favor: its cost-effectiveness. Net managers are forced to buy one PVC per traffic type. But vendors that prioritize on a per-PVC basis say this will be less of a concern as circuit prices drop. "Carriers are advertising lower prices for PVCs all the time," says Heidi Brandt, product manager at Ascend. Protocol Prioritization Corporate networkers who don't want to go with a per-PVC approach can opt for one of the per-protocol schemes supported by 14 vendors. Simply said, these mechanisms enable the ports on a device to recognize different protocols-such as SNA, voice, or IP-and send them out according to priority. At least one early adopter of this approach gives it rave reviews. Don Resh, senior vice president and chief information officer of Retired Persons Services Inc. (Alexandria, Va.), a healthcare organization and prescription mail order company, uses Ascom Timeplex's switches and FRADs. Resh's network consists of T1 lines carrying voice, data, and video between 11 sites-including 2 high-volume automated call facilities and a centralized data center. "Roughly 70 percent of the bandwidth is reserved for data and 30 percent is allocated to voice," says Resh. "And we sometimes use the pipes for videoconferencing." Resh put an ST1000 FRAD at his central data center, and a ST20 FRAD at each location. "The equipment paid for itself in a year," Resh says. And instead of almost 40 T1 lines dedicated to each traffic type, he uses frame PVCs between his central site and the rest of his locations. "I'm impressed with it. It's just like the regular phone network. And video quality is fine." Resh uses protocol-based prioritization and sends voice and data over the same private frame relay connections. Each protocol has its own CIR within the PVC.

To: Immi who wrote (450)	11/5/1997 1:13:00 PM
From: Maverick	Respond to of 1629

Bolt on QoS, Part IV Mix and Match? There's another consideration for net managers who want to build private frame relay nets. Per-protocol FRADs from one vendor can be deployed with per-PVC switches from another-thus freeing them from single-vendor tyranny. Here's the deal: The FRADs set priority by protocol, while the switches don't care what's happening inside the pipe. They just want to set up the PVC. So mixing and matching is possible. Hughes Network Systems is the only vendor that supports prioritization over SVCs. These circuits are set up on the fly, unlike PVCs, which are nailed up all the time. The SVC scheme lets net managers use fewer circuits for the same number of calls. Further, if there's congestion on one circuit, calls can be sent over another. Sounds good. But there's a catch. Thus far, MCI Communications Corp. (Washington, D.C.) is the only carrier to announce frame relay SVC services. Six vendors prioritize traffic on the basis of IP address, divvying up the bandwidth available within a PVC. And three vendors assign QOS according to FRAD port. Traffic on the voice port, for example, could be delivered first. All Backed Up MESSAGE SERVER Each vendor also has its own way of making sure that traffic gets through the network when congestion builds up. After all, it doesn't make sense to go through all the trouble of setting service levels if frames are just going to get dumped. Network Equipment Technologies Inc. (NET, Redwood City, Calif.) offers PVC re-optimization. This mechanism allows the vendor's Framexpress switch to reroute congested PVCs over different circuits (when they're available). Traffic is shunted over a less heavily traveled path until the original path is clear and the carrier switches send fewer BECNs (backward error congestion notifications). It's also important to check whether QOS-capable frame relay gear supports fragmentation, which allows longer frames to be divided up into smaller packets that can be sent more efficiently, thus preventing real-time traffic or SNA from getting caught behind hefty file transfers. Micom's Marathon FRAD segments every frame into 256-byte "cells." On the other hand, Racal Data Group (Sunrise, Fla.), claims that fragmentation wastes valuable processing power on a FRAD or switch. It doesn't offer fragmentation in its Fastframe FRADs. Instead, it deals with congestion via port metering. This allows a FRAD or switch to

To: Immi who wrote (450)	11/5/1997 1:16:00 PM
From: Maverick	Respond to of 1629

Bolt on QoS, Part V slow its port speed whenever the network is congested. Besides Racal, 11 FRAD vendors offer port metering; 9 switch vendors support this feature. Buffering Basics Corporate networkers also need to make certain that their frame relay gear has big enough buffers to accommodate incoming prioritized data. Buffers also are used to hold low-priority traffic while high-priority data passes through a device. Frame Relay Technologies Inc. (Costa Mesa, Calif.) is at the low end with 32 kbytes of memory per frame relay port. Alcatel is at the top of the scale with 64 Mbytes per port. Vendors generally agree that buffering is more important for switches, since they have to cope with a higher volume and concentration of traffic. But two switch vendors, Ascend and Northern Telecom, argue that buffering should be done at the FRAD. This allows switches to devote their processing power to pumping data through the network as fast as possible. Can You Hear Me? If net managers plan on running voice over frame, they need to find a box that can deal with this type of traffic-and keep it from eating up too much bandwidth. Eleven FRADs support voice. The Access Plus FRAD from Nuera Communications Inc. (San Diego) boasts the most compression algorithms: ATC (active tone control) at 7.4 kbit/s to 32 kbit/s, G.729 (ACELP, algebraic code excited linear prediction) at 8 kbit/s, G.728 (LD-CELP, low-delay code excited linear prediction) at 16 kbit/s, G.726 (ADPCM, adaptive differential pulse-code modulation) at 32 kbit/s, and its proprietary E-CELP (extended CELP) at 4.8 kbit/s, 7.47 kbit/s, and 9.6 kbit/s. ACT Networks Inc. (Camarillo, Calif.), Netlink, and Hypercom only support G.729 (ACELP) at 8 kbit/s. Six switch vendors offer voice and voice compression. Another feature to check for is whether PVCs, ports, CIRs, and compression can be configured on the fly. Six vendors, including ACT and Frame Relay Technologies, let net managers set all four parameters from their management interfaces. Four vendors, including Fastcomm Communications Corp. (Sterling, Va.) and IBM, are strictly static, so net managers have to do the job by hand ahead of time. Net managers also will want to check what management interfaces are available. Options include command line, GUI, SNMP, and Web-based.

To: Immi who wrote (450)	11/5/1997 1:18:00 PM
From: Maverick	Respond to of 1629

Bolt on QoS, Part VI Let's Get Physical Physical interfaces are important since they determine what kind of traffic the box can deal with. Obviously, all these devices have integral frame relay ports. Fifteen vendors feature Ethernet, and 10 support token ring. Most offer a range of serial ports V.35, EIA-232, X.21, RS-449, 422, V.36, V.11, V.28, and RS-530. These are used to connect the FRAD or switch to legacy gear like SNA mainframes, controllers, PBXs, or modem pools. Net managers also need to take stock of the protocols these devices can handle since this will determine what traffic can be sent over the network. All of the boxes support SNA and IP; 11 can carry IPX. Net managers looking to make legacy connections also need to know what kinds of SNA traffic a box supports. Async, bisync, HDLC (high-level data link control), and SDLC (synchronous data link control) are the typical offerings. Seven vendors, including Nuera and Hypercom, feature fax capability. CONTACT AUTHOR kcholewka@data.com As always, corporate networkers need to keep a close eye on the price tag. Frame relay switches start at $895 per port. FRADs range from $1,000 to $8,000. For example, Hypercom's Integrated Enterprise Network System FRAD costs $3,000 with one LAN port, one serial interface, and one frame interface. The Voyager FRADs from Jupiter Technology Inc. (Waltham, Mass.) start at $1,000 with two serial ports and one frame relay port. ATM Antagonism But when frame relay vendors are done bolting on QOS, one big question remains. Why bother with frame at all when ATM is designed from the ground up to deliver quality of service? It's all a matter of cost. ATM is expensive. And if net managers can successfully prioritize traffic over frame relay, ATM vendors may have something new to worry about. "It's another slash on ATM's back if frame relay vendors can pull this off," says Jeremy Duke, analyst at In-Stat (Scottsdale, Ariz.). "If you want to save money and can consolidate voice and data, you've got a magic bullet with frame. If frame service providers can back up their claims with guarantees, the ball's in their court."