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Does Cisco's Switch To Linux Make IOS More Open?

When Cisco and Juniper first said they were opening their router
OSes, I thought that they'd be about as open as the iPhone. With Cisco's launch of IOS XE, I realize I
was wrong: The iPhone is much more open.

The update to IOS runs on the ASR-1000, Cisco's new edge router
aimed at both enterprises and carriers. Aside from the usual
improvements in bandwidth and power consumption, its main selling
point is that it can act as a platform for more than just routing,
hosting multiple network services like a firewall, a session border
controller, and deep packet inspection. The router is designed to be
upgradeable for new services, but there's no sign of an API and
Cisco has no plans to let outside developers create these services.

Still, IOS XE is open in one important sense: It's built on
Linux, making the ASR Cisco's first router based on open-source code.
(Or at least its first high-end enterprise router. Home Linksys APs
have been running Linux since 2003.) Cisco last week preannounced its first box that runs
, so the move looks more like part of a general advance
into server territory
than a particular love of open
source. But by router standards (or even Apple standards), Windows is

So far, Cisco plans to run Windows on top of IOS, pitching it as a
way to give branch office users access to familiar print and file
services without actually needing a server. With Linux, it's the
other way round. IOS XE provides the high-level services that control
security and routing itself, but the whole thing runs virtualized on
a Linux core. The Linux part is perhaps more reliable than the IOS
part, as Cisco touts failover as one of the virtualized
architecture's big advantages: If one instance of IOS XE crashes, the
router doesn't.

The ASR-1000 uses Linux's built-in Kernel-based
Virtual Machine
(KVM), which isn't as well known as Xen and VMWare
(probably because no one is pumping millions of dollars into it) but
seems to have gained a following in the embedded space. Last week,
Cisco competitor Riverbed launched
a branch office accelerator that uses KVM to virtualize software from
partners like Infoblox, and the plan is that it will eventually be
able to run user-created apps.

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