It is usually possible to keep pace with growing network traffic—at least for a while—by making incremental upgrades to individual circuits or adding new links in locations with especially high demand. However, there usually comes a time when an extensive network upgrade and redesign is a more sensible choice.
Cisco® made that choice, launching a large-scale project to upgrade its global corporate WAN for higher bandwidth and availability. Companywide factors driving this upgrade include normal growth in network traffic as well as wider employee use of Cisco TelePresence, video, and other bandwidth-intensive technologies.
Other drivers for the WAN upgrade are specific to world regions. Within the United States, the new Cisco data center in Richardson, Texas will change network traffic patterns. Cisco central databases and applications, which previously were housed in a data center at the Cisco campus in San Jose, will be moved to the Richardson data center. One large network impact of this change is that Cisco users in San Jose who previously accessed those applications locally over the LAN will now access them remotely over the WAN from Richardson. Outside North America, additional drivers for the WAN upgrade include the network requirements of the Cisco global R&D campus in Bangalore, India, and a growing number of employees worldwide.
Designing the Corporate WAN for High Availability
Cisco IT wanted to increase bandwidth in key portions of the WAN while maintaining 99.999 percent availability. “The key to achieving this goal was creating a WAN architecture and design that would ensure the continued high network availability and performance necessary to meet Cisco’s business needs,” says Keith Brumbaugh, member of technical staff in Cisco Global Engineering Operations. “We have also defined new network standards and processes, new training for the operations staff, and a new methodology for measuring availability.”
To address Cisco’s network growth demands, the new architecture identifies appropriate levels of circuit capacity, redundancy, path diversity, and fault tolerance throughout the WAN. Based on this architecture, the WAN upgrade will increase the capacity of current major circuits, add new circuits in two world regions, and increase connectivity from major cities to regional network hubs.
“The WAN design also reflects an understanding of the different traffic types and site characteristics at the connected locations,” says Brumbaugh. “For example, the network traffic characteristics will be different for engineering locations compared to offices that house primarily sales and support personnel.”
A New Way to Measure Availability
The new methodology for measuring network availability uses site composite hosts, which respond to pings sent by Cisco’s internal network management system. The pings are sent twice within a 15-second interval and the availability percentage is determined by the number of successful ping intervals. “This method measures WAN availability to the site and the composite hosts allow us to separate site availability from device availability,” says Brumbaugh. “We know that if any device is reachable, then the site itself is reachable.”
Operational and support processes defined for the upgraded Cisco WAN will focus on minimizing the duration and impact of network outages. These processes will also perform detailed tracking of network events to identify and resolve chronic network issues that can affect availability.
Expected Results: Higher Availability and Improved Operations
When the WAN upgrade is completed in early 2008, Cisco expects the following benefits:
- Ability to provide the bandwidth necessary to meet Cisco’s business needs for voice, video, and data applications.
- Lower WAN support costs due to standard equipment and network configurations, and new management processes.
- Improvements in the Cisco network design that will enhance support for video and other bandwidth-intensive network services.
For More Information
Cisco on Cisco
Cisco IT Network Systems Case Studies
Cisco Enterprise WAN Solutions