Defending the router

When Layer 3 switches burst on the scene, industry pundits began predicting the demise of the slower, more costly router as a mainstay of enterprise networks.

Has that happened?

Not exactly.

True, Layer 3 switches are elbowing routers out of the core of enterprise nets for applications such as LAN segmentation and subnetting. In fact, the total market for modular and fixed Layer 3 switches has skyrocketed from a paltry US$34.7 million in 1997 to more than US$2 billion last year, according to Dell-Oro Group in Portola Valley, Calif.

But WAN access and aggregation, multiprotocol support and voice/data integration are keeping – and will continue to keep – routers around for a long time in enterprise networks.

And the market numbers bear that out. Sales of high-end, data-only routers aren’t exactly declining or even flattening out. In fact, sales were up 43 per cent in 1999, from US$1.6 billion the previous year to US$2.3 billion, according to Dell-Oro.

The market for mid-range voice and data routers, meanwhile, grew a healthy 60 per cent, from US$872 million in 1998 to US$1.4 billion in 1999, Dell-Oro states. This is due to small and mid-size companies looking to reduce monthly telephone charges by combining voice with data on the router network.

“What’s often happened is that people that used to have a collapsed backbone routing configuration have replaced that with a Layer 3 switch,” says Dave Passmore, research director at The Burton Group in Sterling, Va.

He adds, “But because Layer 3 switches have traditionally not supported WAN interfaces, they’ve repurposed [routers] and made them the WAN router. The router is no longer handling LAN-to-LAN traffic. That’s being handled by the Layer 3 switch.”

The Internet is also driving sales of high-end routers because service providers need more and more IP routers to accommodate traffic growth. Similar to what’s happening with LANs, legacy routers are not going into the core of the Net, but around the edge, aggregating traffic from access points, tagging it with VPN identifiers and feeding it into a new class of gigabit-speed routers performing many routing functions in hardware.

Cisco rules the router market

When it comes to high-end legacy routers, Cisco Systems Inc. is the dominant player, with 88.1 per cent market share – the only competitor of any consequence is Nortel Networks Corp., at 11.2 per cent – so Cisco’s product road map pretty much determines how routers and switches will be used.

Investment giant Merrill Lynch is an example of a large corporation redeploying traditional Cisco 7X00-class routers as WAN aggregation devices. Last year, when Cisco introduced its Catalyst 6500 LAN routing switch – which is what many would call a Layer 3 switch — it changed the game for the 7X00 router, as far as Merrill Lynch was concerned.

Merrill Lynch’s network serves 68,000 employees in 950 global branches. The network spans five continents, goes from 56Kbps dial-up and T-1 Frame Relay access connections to E-1 and DS-3 backbone links and consists of 1,800 to 2,000 Cisco routers, 45 per cent of which are Cisco 7X00-class high-end devices.

“We’ve made a big investment in these 7500 series routers, but we don’t think they’re a strategic investment – that’s why we’re not buying more of them,” says Nicholas DeVito, director of technology infrastructure services at Merrill Lynch. “We’re pushing them more out to the WAN, and we’re replacing them as LAN routers with something like the 6500 series. We can deploy far more port densities in terms of high-speed Ethernet – 100Mbps with Gigabit backbones” with the 6500s, he says.

If Merrill Lynch needs to buy more WAN routers for new sites, the company is inclined to go with Cisco 12000 Gigabit Switch Routers, which scale from 40Gbps to 80Gbps and are targeted predominantly at service providers.

Even so, there are some pretty solid reasons why the 7X00 series routers will continue to have a place in the networks of Merrill Lynch and other enterprises.

For example, the 7500 is the only router or switch that supports Cisco Channel Interface Processor, a card that attaches to an IBM mainframe and connects legacy IBM SNA networks to IP networks without the need for an SNA front-end processor (FEP).

Merrill Lynch is looking to replace about 100 of those IBM FEPs with channel interface processor (CIP)-enabled 7500s. That may require the firm to continue purchasing 7500s, even if not for WAN routing, DeVito says.

“The 7500s are working well for that particular function, and given the data centre mind-set, they like going with stuff that works,” he says. “Over time, I’m sure we’ll replace them, but in the short run, we’re happy with the way they’re performing. So we might buy a few more 7500s with CIP cards just for that very purpose. But by no means or stretch of the imagination do we see that as a major or significant investment; it’s just pockets here and there where we need to supplement for performance or capacity.”

Multiprotocol support

Another key feature of routers that keeps them around is the ability to route multiple protocols. Layer 3 switches usually support only IP, or IP and IPX, and do not include most of the software feature sets included in high-end routers.

“If you weren’t running AppleTalk, you wouldn’t need routers,” says James Wiedel, director of networking at the University of Southern California (USC) at Los Angeles. “And if you weren’t going anywhere, you wouldn’t need a router at all with the Layer 3 switches.”

Two years ago, USC replaced some old Cisco AGS+ routers with Layer 3 SmartSwitches from Cabletron. USC uses Cisco 7500s to route packets between networks and handle legacy, or non-IP, traffic. In all, USC has replaced seven AGS+ routers with SmartSwitches and two 7500s.

“The 7500s are doing WAN aggregation and routing random protocols, all the non-IP stuff,” Wiedel says. “Our Layer 3 stuff cuts through the VLAN so that need not even touch the routers, unless you’re leaving a domain and going somewhere else. We’re using [routers] on the wide-area links because they do a little better job of not passing lots of traffic over the slow WAN links.”

Wiedel says USC hasn’t increased the port count of its 7500s “in years” even though the school’s network has grown significantly. The network growth is being handled by Cabletron SmartSwitch 6000s with the company’s SecureFast cut-through switching technology. In all, USC has about 30,000 switch ports, mostly 100Mbps and 1Gbps Ethernet.

“Right now, SecureFast has some real wins in it for us,” Wiedel says. “It does a lot of the routing and it takes the load off of routers. That’s not true of most other manufacturer’s stuff that’s running IEEE 802.1p and Q [frame-tagging protocols]. They require a router to get in between the VLANs.”

But even SecureFast cannot block out all of the broadcast traffic a flat, Layer 2 network is known for.

“There would be a lot of broadcast traffic that would carry over the WAN links that you really don’t want out there,” Wiedel says. “You still need the routers to shut up a lot of the noise.”

Wiedel envisions keeping USC’s two 7500s around for the short term. Longer term, though, they’ll be replaced, he says. “At some point in time, they’ll swap out for something else, but I don’t know what that something else is.”

Software giant PeopleSoft has an idea what that something is: Cisco’s Catalyst 6500 routing switch with FlexWAN adapters.

FlexWAN debuted earlier this year as a way to “WAN-enable” the 6500 so it could serve as a single routing and switching platform to consolidate LAN, metropolitan-area network (MAN) and WAN services. By doing this, users can lower their cost of equipment ownership, simplify network design, ease network management, and migrate existing MAN and WAN networks, such as those based on routers.

To foster the migration, FlexWAN even uses the same T-1, T-3, ATM and packet-over-SONET WAN port adapters as the 7500 and Cisco 7200 routers. This seems like a simple, straightforward replacement for those traditional routers, which one would assume might now be ripe for retirement.

But Cisco stresses that the 7500 can still be used as a high-density enterprise WAN edge device with a “sweet spot” in T-1/T-3 aggregation. The box can also function as a virtual private network gateway and supports IBM SNA connectivity through the CIP. Cisco even added voice to the 7500 platform earlier this year via a new Multiservice Exchange chassis that supports a circuit-switched bus.

But PeopleSoft’s routers don’t need to be heard; they need to be pumped up.

“We keep getting into oversubscription problems,” says Stan Christensen, director of network engineering at the Pleasanton, Calif., software company. “We’ve got a lot of packet-over-SONET [interfaces] connecting a lot of the metropolitan-area networks together on those units as well. So we’ve had to keep adding multiples of 7500s just to keep them from oversubscribing too much.”

PeopleSoft has been testing the 6500 with FlexWAN modules. With the 6500/FlexWAN combo, PeopleSoft can stuff as many packet-over-SONET modules as needed without oversubscribing the switch.

“We’re going to put it into testing and then production to see how it flies,” Christensen says of the 6500/ FlexWAN combination. “If they do it right, it could easily replace the 7500. I don’t see any reason why it couldn’t. For us, it could pretty much replace everything we use the 7500 for.”

Down, but not out

So the role of the router is clearly changing.

Traditional, CPU-based, software-intensive routers, like the Cisco 7500 and the Wellfleet/Bay/Nortel BCN, may be a dying breed, but their function is still critical. Those functions will just be subsumed by a new generation of higher-speed, hardware-intensive routers that, for all intents and purposes, could be marketed as a switch.

“Traditional routers will, over time, be enhanced with their own ASICs and the like,” says Eric Hindin, formerly an analyst at The Yankee Group in Boston. “I think they have plenty of life. If nothing else, there are so many of them out there, you and I will have long since moved on by the time there’s no role for them in carrier and enterprise networks.”