Virtualizing Servers on Routers, If Cisco Approves

Cisco today goes some way towards making good on its promise to open up IOS, at least as far as the version running on its ISR (integrated services router) is concerned. The router will also be able to run third-party applications created using a Cisco SDK, the first step in Cisco's attempt to replace servers with network infrastructure

devices. While IOS still isn't as open as Windows (let alone Linux, on which it's based), it will allow customers to port their apps to the ISR, reducing the need for branch office servers without backhauling traffic to a data center.

Though Cisco has been the most vocal about its plans to move into server territory, it isn't the first company to ship a platform for running applications on a router. That honor went to 3com, whose OSN (open service network) first shipped about a year ago, and since then Riverbed has launched a similar initiative with WAN optimizers.

Architecturally, Cisco's product looks very similar to 3com's: Both involve branch office routers, and neither place applications directly on the router. Instead, apps run on a separate add-on module that's essentially a (very) scaled-down blade server. Requiring a separate module increases costs compared to the software-only approach of competitor Riverbed, but it helps isolate apps from the routing infrastructure while augmenting the router with the processor, memory and hard drive necessary to run x86 code.

While 3com gets by with a single OSN module, Cisco has two separate products thanks to the different expansion slots used by different ISR models. Modules are available for the mid-to-high-end 1841, 2800 and 3800 ISRs, with memory capacities ranging from 256 MB to 2 GB. This isn't much by server standards (or by any standards), but it's similar to 3com's 1GB. Both are aimed very much at running services used by a small workgroup at a branch office, not to virtualize entire datacenters.

Cisco's modules run what it describes as the AXP (application extension platform), a new version of IOS built on a Linux foundation. This is designed to make porting apps to the module relatively easy, but the presence of a Cisco proprietary layer means that the OS isn't identical to any Linux distribution. At minimum, Linux apps need to be recompiled. For them to usefully access the router's features, they also need to be rewritten to use its APIs.However, the router can't load just any application. Its security architecture requires signed code, and Cisco is keeping the private signing keys closely guarded. Every application needs to be to be approved by Cisco before it will run, even those developed by customers for their own internal use. Cisco says that it will give customers the keys at no cost once an application is approved, but the thought of needing to get approval at all will clearly make some users question the router's openness.

The API itself is only accessible to applications running directly on the module, meaning that the module's memory constraints place could place severe restrictions on what it can be used for. However, customers or third-party developers can get around this by writing an agent on the module that passes data to a Java or Windows server elsewhere.

Like 3com, Cisco has signed up several partners to develop apps for the router, though the two vendors have different partner strategies: Cisco already has its own products for security, VoIP and the kind of apps that 3com is targeting. Initially, Cisco has nine partners including Avocent, whose LANDesk management software will be able to run on the device.

The others are all in the unified communications area or targeting specific industries. For example, Sagem-Interstar has an application that intercepts faxes on VoIP lines, while NICE Systems has one for recording telephony streams aimed at financial services and government. Cisco reseller ICW Systems bundles the ISR with medical record keeping apps, calling the package a Healthcare Router.