by Ed Tittel
Everybody knows the benefits of migrating to MPLS: better reliability, increased performance, and lower costs. (A primer podcast is available here [MP3], via Hill Associates, and we’ve developed our own whitepaper on the subject.) The downside is low visibility and access into the MPLS cloud. How can you be certain your carrier is delivering consistent levels of performance when traditional measurement techniques such as trace-route and ping offer no help, and probes are costly and difficult to maintain?
Try utilizing the flow statistics that are captured by almost all current routers. The most common format for flow statistics is Cisco IOS® NetFlow technology. While originally developed as an advanced packet-switching technology, it has become the de facto standard in flow-based data collection, not only for Cisco devices but throughout much of the networking industry.
Additionally, there is strong momentum within the IETF to arrive at a flow measurement standard similar to NetFlow, as described in RFC 3917. This router-based approach has significant advantages over probe-based approaches in terms of cost and maintenance. It’s known as IPFIX and we hope it becomes widely used on all kinds of networking gear.
Using probes to monitor traffic on a link-by-link basis presents significant costs — not only in terms of up-front purchase costs but also for ongoing maintenance and upgrades. And most probes need to be replaced whenever the links they monitor get upgraded.
On the other hand, most routers already have flow-measurement technology built right in, so there’s no probe to upgrade when a link is upgraded. Today, many switches also incorporate router modules and can also measure flows as well.
By working with the technology built into your existing routers and switches, you can maintain visibility in terms of application throughput for remote sites without breaking the bank — or instrumentation.
Ed Tittel is the author of the Exam Cram series of computer trade books, and has written over 130 books in total.
- MPLS Network Performance Assurance: Validating Your Carrier’s Service Level Claims