MPLS test tools go to the core of interop; voice, video, data convergence spurs wider technology deployment

MPLS test tools go to the core of interop; voice, video, data convergence spurs wider technology deployment

Bruce Miller

Today’s telecommunications landscape is being shaped by several factors. Service providers and carriers are increasingly focused on their return-on-investment for existing network capacity, as opposed to the wholesale addition of new network assets. IP is emerging as the protocol of choice for their backbones and is a key to reducing costs. IP-based virtual private network (VPN) services are emerging as more economical alternatives to conventional network connectivity.

What’s the ultimate goal? Simply, it’s the convergence of voice, video and data onto a common network. Together, these forces are spurring the adoption of multi-protocol label switching (MPLS) in more and more service provider networks.

Use of MPLS technology clearly is on the rise with telecommunications providers. Virtually every major carrier in the U.S. (as well as many internationally) are either deploying or announcing plans for MPLS backbones. Key to the technology’s adoption is its ability to handle a variety of traffic types and services, both legacy and new, over a single network. MPLS enables higher-value applications and services to be delivered from the service provider’s network by reducing requirements on customer-premises equipment. Beyond carrier networks, MPLS is also finding its way into larger enterprise networks as well.


MPLS is based on the concept of label switching: an independent and unique “label” is added to each data packet with this label used to switch and route the packet through the network. The label is simple–essentially a shorthand version of the packet’s header information–so network equipment can be optimized around processing the label and forwarding traffic. This concept has been used in the data communications industry for many years–ATM, Frame Relay and X.25 being examples. But MPLS has one distinct advantage: it uses the same routing and host addressing schemes as IP, again the key protocol being used in today’s networks. By overlaying a connection-based model onto the traditionally connectionless framework of IP, a wealth of new possibilities is opened up for managing traffic on IP networks.


While MPLS defines a new means of communicating over IP networks, the real interest lies in what is enabled at the application and services level. Key among these is Virtual Private Networks (VPNs). A VPN is a private network service delivered over a public (shared) network, allowing remote locations to be securely connected without the expense of dedicated network lines. MPLS enables VPNs by providing a circuit-like, connection-oriented framework, allowing carriers to deploy VPNs over IP. MPLS VPNs provide security inherently through their connection-oriented nature, making IP as secure as Frame Relay or ATM and reducing the need for encryption.


Despite its apparent simplicity on the surface, MPLS has evolved into a very complex technology, encompassing a wide range of functionality and applications. Today, more than 100 standards and draft specifications define the technology and its applications. Organizations looking to deploy or develop MPLS must consider its complexity, its continually evolving state, and its impact on network performance and scalability. For network managers and MPLS products and services vendors, a comprehensive and well designed conformance and performance test plan, executed by fully capable test tools, are imperative to the successful deployment of MPLS technology.

Conformance testing is typically used early in the development cycle to ensure a product’s compliance with MPLS standards. Proper compliance with industry standards is crucial to achieving interoperability in today’s heterogeneous networks. The conformance test solution utilized must be able to fully exercise the control plane of the device or system under test.

Performance and scalability testing is used to determine whether a device can handle the real world requirements of the network into which it will be deployed. A real network can be set up to perform this testing. However, this quickly becomes a very costly option when hundreds of routers are involved.


To achieve high levels of scalability, test solutions are used to emulate multiple MPLS routers at the control plane level and scale up for large capacity testing. Multiple IP routing and MPLS signaling protocols are emulated to simulate the test network. Data traffic is driven through the system at the data plane level to fully stress the device being tested. Purpose-built test hardware is required to provide the flexibility and scalability needed to adequately emulate a large network. For example, up to thousands of IP interfaces must be supported per network port for large network simulation–requirements that standard off-the-shelf hardware cannot support.

An increasingly common requirement for test tools is the ability to emulate real enterprise applications over the network. This allows for the characterization of end-to-end application performance prior to deployment–essential for today’s mission critical network applications.

In summary, MPLS has proven its value to service providers and carriers by enabling the convergence of new and legacy network services over a common network, allowing the realization of significant operational cost savings. As a result, MPLS is well into mainstream deployment in networks around the world as a standard IP-backbone technology for converged networks. Critical to this deployment are the proper testing methodologies and tools that enable the providers of next-generation MPLS products and services to ensure the reliability, performance, scalability, and interoperability of their offerings.

Bruce Miller is a product line director for Ixia, an IP network testing solutions provider.

COPYRIGHT 2004 Advanstar Communications, Inc.

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