Why should you use MPLS traffic engineering technology?
MPLS VPN is often used by IT management as a catch-all term when procuring a Layer 3 virtual private routed network (VPRn). VPRn products are combined with the traffic engineering technology properties of Multiprotocol Label Switching (MPLS) to support national and global networking. The question remains: When should organizations make use of VPRn networks based on MPLS?
The MPLS protocol is found within the majority of large service provider networks -- networks that have often been built over several years at significant investment. In order for providers to make the most of their assets, MPLS has evolved and introduced new capabilities over and above VPRn.
Today, IT management is faced with a decision-making process that presents multiple options, from Internet protocol security (IPSec) and Secure Socket Layer (SSL) virtual private networks (VPN) through to Layer 2 virtual private LAN service and metropolitan area networks. Depending on the size of your business, a mix of these services is generally used to best meet your architectural design requirements. All of these services are available using the scalability and breadth of MPLS network providers.
Service providers use MPLS for a variety of reasons, but primarily for traffic engineering. MPLS allows service providers to determine the most optimal route across core networks. To understand why a service provider would require traffic engineering, we need to consider the challenges faced when core networks are created.
Routing protocols decide to route traffic based on their algorithms. Open Shortest Path First (OSPF), for example, ensures data will follow the shortest path to the required destination. Yet the shortest path may not be the most efficient path; it may be bandwidth-constrained. With this in mind, providers may wish to engineer the traffic to follow a longer, more bandwidth-rich route.
For R1 to reach R7, OSPF would send the traffic via R5 and R6 (shortest path). However, what if the more efficient route is via R2, R3 and R4? MPLS will define a path through the network based on the provider's instructions and decision-making process. Once a path is established, all routers within the network will append a label to the data that will designate a primary route. It is worth noting that the underlying routing protocols may be used for path selection in the event of an outage.
A VPRn offering will define how your traffic will perform and what traffic types are supported, provide a wealth of statistics (to provide trend reporting) and generally enable a platform to support inter-site traffic without too much effort.
Today, IT management must provide a predictable level of service to their users and extranet clients to maintain a competitive edge. MPLS VPRn provides an opportunity to outsource management of devices to the service provider, or, if you have the capability, to retain the management of edge routers.
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