Pipeline Publishing, Volume 4, Issue 4

	This Month's Issue:
	Maintaining Network Health

VRF - The Key to MPLS Performance Assurance

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The ultimate challenge, regardless of the approach that is chosen, is in adapting the data sets to accommodate the dynamic behaviors of MPLS and deliver a means to consistently and accurately track activity by customer.

VRF to the Rescue

In order to segregate monitoring of each customer’s traffic, operators must first look at the MPLS label attached by the first Provider Edge (PE) router when the packets enter the network. Each customer and the routes their traffic traverses are both unique and dynamic, so the MPLS labels for each associated customer and PE router will be also be unique and will change as routes do. The key challenge is to be able to track and accommodate these updates in real-time.

In order to track, monitor, analyze and trend any customer data for both ingress and egress traffic that may have different labels from each end of a route, a more practical approach is to look beyond the dynamic MPLS labels to a more stable and consistent identifier. The VRF (Virtual Route Forwarding) table maintained by each PE router represents a better basis for monitoring and management. VRFs are normally assigned on a customer-by-customer or service-by-service basis, and do not change dynamically as do MPLS labels. By monitoring dynamic routing data, it is possible to establish the relationship between the MPLS traffic and VRF assignments, thus maintaining a consistent categorization of customer and service traffic.

With a real-time mapping of traffic flow metrics to VRFs, operators can much more readily monitor, characterize, and understand the activity and experience of each served customer and each active service. This capability is further enhanced by adopting a DPI-based data source, which provides the broadest and deepest information on both service volume and quality. Following are some common, everyday tasks that DPI-based VRF visibility enables:

Identifying “bandwidth hogs” by viewing a core network segment and distinguishing between multiple individual VRFs assigned to it simultaneously
Performing in-depth, packet level troubleshooting of an individual customer’s activity to analyze and discover root cause of degradations
Setting utilization or time-over-threshold alarms by VRF to recognize and address impending congestion problems before service quality issues impact customers
Reporting on most utilized circuits highlighting individual VRFs to reveal that changes in bandwidth or new traffic prioritization schemes might be needed to accommodate “power user” customers or locations

There are other uses for VRF-based monitoring as well. In some provider environments, especially mobile operators that are delivering IP-based 3G+ services across an IP/MPLS core, VRFs are used to segment services and content sources. They may also be used to segment and manage Operations, Administration, and Maintenance (OA&M) traffic transiting a common core with revenue-bearing traffic. In these cases, monitoring performance and activity by VRF provides details regarding customer experience with the added benefit of revealing network and service behavior by service and/or business function.

In the end, it’s all about customer assurance no matter what technologies you’ve deployed. The key ingredient to making this happen is to always have the appropriate visibility into the services delivered, the customers using them, and the network infrastructure delivering them. To use an analogy, not having this visibility would be the same as a pilot flying an expensive jet in the dark without instrumentation that gives the appropriate visibility -- common sense, don’t you think?

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