Atlanta - Users looking to add Layer 3 switching to their ATM networks could be in for a rude awakening.
Depending on the equipment they use, customers may face a disruptive and costly upgrade to add Multi-Protocol over ATM (MPOA) capabilities to network edge devices. MPOA allows ATM backbones to support Layer 3 applications and protocols, such as IP and IPX, and lets them take advantage of ATM's quality-of-service features.
For some equipment - notably gear from FORE Systems, Inc., Bay Networks, Inc., Newbridge Networks, Inc. and possibly Cabletron Systems, Inc. - getting MPOA support may only require a software upgrade. But for users of products from such companies as Cisco Systems, Inc. and 3Com Corp., the upgrade will involve swapping out hardware - and that could cost a lot in time, money and network reconfiguration.
"You need to be real, real careful to understand what the benefits of extending MPOA into your network are going to be, and make sure you only extend it as far as the benefits will cover the cost," said Tom Nolle, president of CIMI Corp., in Voorhees, N.J. "The closer to the desktop you come with it, the more costly [it is]."
ATM networks with more than 4,000 users will be those most likely to add MPOA to the edge for greater scalability and higher Layer 3 performance, vendors said. Conversely, smaller networks likely will retain Layer 2 LAN Emulation functionality at the edge and rely on a central MPOA server for route calculation and forwarding.
"It's not the cost of upgrading five systems or two systems in the data center; it's upgrading what you have in the wiring closets, which tends to be a far greater number," said Melinda Le Baron, a research director at Gartner Group, Inc., in Stamford, Conn.
Cisco and 3Com users face the most dramatic upgrade to MPOA. For Cisco customers, the move will require replacing the OC-3 LANE card in the Catalyst 5000 switch with an OC-12 MPOA card coming early next year, said Dave Benham, Cisco's ATM product manager. An OC-3 MPOA card will come months later, and Cisco routers with ATM interfaces require only a software upgrade, he said.
Benham would not say how much the MPOA-enabled OC-12 and OC-3 cards will cost. Cisco's current OC-3 LANE cards for the Catalyst 5000 cost about $10,000. MPOA will be backward-compatible with LANE, he said, so users need not deploy MPOA everywhere.
Nonetheless, Cisco's upgrade plan caught some users off-guard. Doyle Friskney, director of communications and network systems at the University of Kentucky in Lexington, was hoping that Cisco would provide MPOA as a flash RAM download.
"I have 30 Catalyst 5000s on campus so it will be a major board swap-out," he said. "I assume if you have some kind of maintenance plan, you're going to be in good shape. I've never had a major [upgrade expense] problem with Cisco. My worry will be more on how will I do the transition and should I even do the transition."
"We have 15 Catalyst 5500s on campus," said Allen Robel, senior network analyst for Indiana University's computer services department in Bloomington. "We would have to upgrade all of those."
3Com suggests customers consider the transition to MPOA very carefully because it will require them to replace 3Com Layer 2 switches, said Rick Forberg, product line manager of ATM internetworking at 3Com.
"You can't run a Layer 3 forwarding process on a Layer 2 edge device, and I'll grant you that most 3Com edge devices are Layer 2," Forberg said.
He recommends the company's Fast IP technology for Layer 3 switching at the edge of the ATM network. But Fast IP has its drawbacks. For one thing, it is proprietary, while MPOA is a standard. Also, MPOA allows you to route a packet between Ethernet and token ring. With Fast IP - which does Layer 2 forwarding - a packet that comes in Ethernet has to go out Ethernet.
"3Com realizes the move to MPOA is disruptive, which is why we offer Fast IP," Forberg said. "Fast IP lets you do the same things as MPOA but you don't have to replace Layer 2 switches. Customers could save hundreds of thousands of dollars."
3Com will support MPOA because customers likely will want it as they replace devices in the future. The company is expected to announce its MPOA plans for its CoreBuilder 3500 and 7000 switches at this week's NetWorld+Interop 97.
FORE's MPOA strategy requires only a free software upgrade to core switches, edge devices and ATM adapters, said Michael Ladam, product manager at FORE.
ATM adapter cards and Layer 2 Ethernet switches with an ATM uplink need a new software driver to support MPOA.
There is no question in the mind of Sergeant James Chlebus, functional area network manager for the U.S. Air Force's 17th training group in Texas, that his FORE boxes are MPOA-ready. But an upgrade might not be so easy with his Cabletron equipment.
"We're told that Cabletron isn't so sure about a software upgrade," Chlebus said. "They told us they are looking at MPOA as a firmware/hardware upgrade depending on the product. A firmware upgrade - if not a flash download - can require an additional card to work."
"It's easy to upgrade to MPOA," said Tim Hale, ATM program manager at Cabletron. "It's just a matter of a flash download of MPOA code onto the devices."
Cabletron's MPOA firmware upgrades will be available in the first quarter of 1998 and free for most customers, Hale said. Bay Networks also will come out with standard-compliant MPOA software for its Centillion 100 and System 5000BH devices in the first half of next year, said Brian Brown, director of product strategy for Bay's switching products.
Newbridge has been one of the most bullish MPOA supporters. The company has been shipping a prestandard version of MPOA for some time.
"If you've got our Layer 3 edge devices or ATM switches, you're all set since we've been shipping prestandard MPOA product for more than a year," said Lou Martinage, manager of product marketing at Newbridge. "And if you want to add existing Layer 2 LAN switches to the mix, you just connect them into our MPOA edge devices."
