What is a router?

Is a router still a router even if forwarding packets is just one of its many jobs?

View slideshow on the Evolution of Routing

More and more applications, such as firewalls, VPN concentration, voice gateways and video monitoring, are being piled onto routers. Cisco's Integrated Services Router (ISR), for example, even boasts an optional application server blade for running scores of Linux and open source packages.

"A customer came to us inquiring about all the services on a router but they did not need the routing capabilities," says Inbar Lasser-Raab, senior director of network systems at Cisco. "It's becoming a hosting platform for any service linked or tied into the routing capability."

Click to see: A short history of the router

About a fifth of Cisco's annual $35 billion to $40 billion in revenue is attributable to sales of enterprise and service provider routers. And the worldwide router market in 2008 was just less than $13 billion, according to Dell'Oro Group.

But those numbers might become harder to track as the definition of a router changes.

"Whether you call a particular platform or chassis a router depends on what the thing is primarily used for," says Jeff Doyle, president of consultancy Jeff Doyle and Associates and a Network World blogger. "Media gateways, firewalls, GGSNs, etc. They might all have router functions in them, but they are generally called by whatever their primary role in the network is."

In many respects routing has become a more general purpose utility on a hardware platform not exclusively optimized for routing. The routing aspect becomes back-of-mind as the capabilities of the device's other applications and services are of more immediate need.

"As the hardware has evolved…it's similar to the hardware that's used for servers," says Eric Wolford, senior vice president, marketing and business development at Riverbed, which makes WAN optimizers. "The software becomes a bigger and more important part of deciding what it is. Routing is the software logic that does the connecting of the dots. Routing can be done on a variety of hardware platforms.”

Vyatta, for example, runs Linux-based routing code on x86 hardware. It also runs several other open source network applications on the standard hardware, including firewall, VPN concentration, virtualization, address management, traffic management and intrusion prevention that scales from the branch office to the service provider edge.

"In the old days, vendors developed a new box around a new function; we're now seeing a move to bring all of these functions together," says Dave Roberts, vice president of strategy and marketing at Vyatta. "It doesn't make sense every place in the network to plop down three different boxes, or four or five and daisy chain them altogether. It makes sense to still have all these functions but as pieces of a larger system that plays in different places in the network -- more of a general purpose device that supports a lot of functionality."

Vyatta customer New Mexico Courts says the more features that are added to a router, the more the software component of routing is distinguished from the hardware. Time was when router hardware – specialized ASICs and packet processors – was intrinsic to the function itself.