Service Provider Networks / Internet Routing / View from the Edge:

A route around redundancy?

Leaders say two routers will always be needed/p>

By Jim Duffy
The Edge, 05/31/02

Despite recent announcements claiming the contrary, the two leading makers of Internet routers say it's doubtful routing will ever be so reliable that you won't have to deploy a redundant router for backup.

Responding to a question last Wednesday at his company's first-ever worldwide analyst meeting, Juniper Networks founder and CTO Pradeep Sindhu said, "Technologically, we [presumably meaning, the industry] don't know how to do this. [Routing] software is complex, you cannot anticipate all of the failure situations."

And then a day later, Roland Acra, the vice president and general manager of Cisco's Internet Routing Group, concurred during an interview with this reporter.

"Software continues to be imperfect," Acra said. "Even if the software is rock solid, you want to minimize dependence [on a single system] and also to protect against human error. We're certainly shooting for not having the need for it, but we also want to be realistic."

Cisco recently announced Globally Resilient IP, software designed to keep packets forwarding and link sessions intact while routing protocols restart. And back in February, Juniper announced a "graceful restart" capability in its JUNOS operating system that's also designed to keep forwarding packets as routing protocols reboot.

In between was an announcement by telecom old guard Alcatel, which is mildly intriguing because it comes from a company that has built reliable telephony equipment for decades. But the jury's still out on Alcatel as a router vendor.

Meanwhile, Juniper claims it's been performing fault-tolerant, "nonstop routing" in its JUNOS operating system for over a year. And Cisco's Acra said his company has some Tier 1 customers that have experienced several quarters in a row of 99.999% router reliability.

But still, carriers are required to purchase, configure, install, operate, manage and maintain a separate, stand-alone redundant router "just in case" - and in every POP. I wonder what the capex/opex and IP service profitability implications of this are...

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A couple of router companies, however - one trying to stay on the core router radar screen, the other not yet shipping product - beg to differ with Cisco and Juniper on the redundant router requirement. Avici Systems last week announced software for its Stackable Switch Router and Terabit Switch Router designed to deliver 99.999% reliability in a single router, which Avici says eliminates the requirement for service providers to install two routers at each point in their networks for redundancy.

Avici is so confident in its implementation of routing resiliency that it is offering customers a service-level agreement (SLA) guarantee of 99.999% reliability or it will refund a portion of a service provider's maintenance fee.

The other company is Caspian Networks. The start-up is developing a "super" core router based on the principles of supercomputer multiprocessing that's intended to be as reliable as telephony switches and cross-connects, thereby eliminating the need for a redundant routing system.

Caspian says it will also offer carriers an SLA for reliability with a single router.

IP routing that's reached the single system state of reliability is one to two years away, Caspian says, which is expected to have shipped its router into a production network by this fall.Caspian also says that if the Ciscos and Junipers of the world could start over again right now, they could develop software reliable enough to eliminate the need for a redundant router.

Granted, IOS has been around for 15 years and its roots are in enterprise networking... but talk is cheap, especially from a start-up and a vendor barely eking out 2% market share. JUNOS has not yet had a major, headline grabbing failure that this reporter can recall.

Then again, it does require two routers.