Networking environments can be harsh. Outdoor environments are often harsher!

Do not try this at home.When testing your Cisco switches for high availability capabilities, we recommend not setting them on fire, crashing into, or flooding them with water. However, we do have some experience with these situations and our switches keep running.

The network must operate 24 hours a day. With many devices and applications running on the network, oftentimes a few seconds of downtime can mean tens of thousands of dollars in financial loss. And yet, none of these usual measures for uptime take into account an actual physical disaster.Indeed, seldom do people think about what could happen to their switches in the physical environment that they are being deployed.

A case in point: Consolidated Communications delivers fiber to the home (FTTH) in six different states. As they thrive to deliver high availability and performance to their customers, their fiber infrastructure relies on Cisco Catalyst 4500E switches. In fact, Consolidated Communications has been relying on Cisco Catalyst 4500E switches for over 15 years: they were one of the very first customers of the Catalyst 4500.

On February 21, 2014, a utility truck lost control and rammed through a remote terminal (RT) of Consolidated Communications, in Sacramento, California.The crash killed the power to the remote terminal and extensively damaged the equipment that was in it, including the Catalyst 4500E. The 4500E's chassis was partially crushed and its fans were non-operational.

Quickly and in the middle of the night, the technical team of Consolidated Communications came to the rescue to restore service to their customers. To their surprise, right when they turned the power back on, the Cisco Catalyst 4500E restarted and functioned as well as it had before.

What happened with Consolidated Communications' 4500E isa testimony to the sturdiness of the Catalyst 4500E. By being switched right back on, the Catalyst 4500E saved Consolidated Communications further financial loss.

The Catalyst 4500E offers resiliency both inside and outside.On top of that switch being physically sturdy, the Cisco IOS XE software that runs inside was built to maximize network uptime.Its high availability features can eliminate network disruption. Here are a few examples of what it does:

• For planned downtime, In-Service Software Upgrade (ISSU) supports full software upgrade without being taken out of service.
• For unplanned downtime, features like Nonstop Forwarding and Stateful Switchover (NSF/SSO) with dual supervisor configuration ensure transparent supervisor engine switchover in case of failure. In addition, Virtual Switching System (VSS) pools two Catalyst 4500E into a single virtual switch. Stateful failover between the supervisors on the two chassis provides sub-second failover and transparent failover even to delay-sensitive applications such as voice and video.
• And system-level resiliency addresses mean time between failures (MTBF) with redundant uplink ports and redundancy built on all critical components (supervisors, fans, power supplies).

These high availability features are further detailed in the Catalyst 4500E-Series High Availability at-a-glance and in the Catalyst 4500E-Series High Availability white paper that are available for free online.

Through my years at Cisco, I have heard about switches that have been flooded, crashed, or burned, and yet they still ran.Every new story of resiliency and disaster recovery makes me proud. At Cisco we thrive to deliver excellent quality, right down to the very bones of our switches. So that even when accidents happen you can rely on Cisco products and solutions.