MPLS in the Access: Creating Differentiated CoS for
IP-based Services

Guy Chenard has 20 years of communications industry experience and has successfully driven a broad range of communications systems to market leadership positions. Chenard joined Integral Access from Premisys Communications, which was recently acquired by Zhone Technologies, where he was General Manager of broadband products and Senior Director of business management. He has held key management positions in business development, sales and marketing with Harris Farinon Division in both the US and Canada. He holds a BS in Electrical Engineering from Ecole Polytechnique of Montreal University in Quebec, Canada.

MPLS World News: MPLS first found application in operators' networks, essentially allowing them to offer VPN services. But MPLS is also starting to become more prevalent among smaller operators who are seeking to offer integrated access services. Do you think that access constitutes the next market for MPLS?

Guy Chenard: Yes, absolutely. Our vision when we began developing the PurePacket (http://www.integralaccess.com/prod_node.htm) system in 1997 was that MPLS is the best alternative for building IP-based integrated access networks - and now the market is adopting and validating that vision. The benefits of using MPLS in the access are very compelling for carriers and end-customers. Along with standard IP QoS such as IntServ, MPLS enables carriers to more efficiently manage QoS, and create differentiated classes of services for IP-based voice, data, and video services. It reduces the high bandwidth requirements relative to VoIP as well as the cost and complexity associated with VoIP header compression, which is extremely important in resource constrained and cost competitive access networks. MPLS also allows for a native IP network which provides dynamic sharing of network resources between applications, and facilitates the creation of new services.

MPLS World News: Did the MPLS Forum's Implementation Agreement for Voice over MPLS (VoMPLS) have a triggering effect on the eruption of MPLS in access?

Guy Chenard: Yes. The new VoMPLS standard is spurring vendor innovation and carrier deployment of MPLS-based communications equipment. Carriers are recognizing the power of VoMPLS for very efficiently transporting voice services across IP/MPLS networks, managing call quality, and optimizing bandwidth utilization in access networks. From the very beginning Integral Access has been using an implementation of VoMPLS in the PurePacket system to deliver packet-based voice services. Thanks to this feature, we are seeing accelerating demand for the system: currently we have six customer deployments in the United States, and seven in Germany. Integral Access also played a central role in the creation of the VoMPLS specification. We chaired the Application and Deployment Working Group of the MPLS Forum, and edited the VoMPLS specification.

MPLS World News: What are the arguments for deploying and using MPLS in access networks? What are the advantages in terms of service and cost for companies such as Integral Access, who sell voice and data over IP to operators?

Guy Chenard: Using MPLS, Integral Access has developed a 100 percent IP solution that enables carriers to take advantage of the operational and cost efficiencies of deploying a single packet-based access network that supports all their services. In addition, MPLS enables connectionless IP networks to behave like connection-oriented circuit switched networks, so that carriers can provide toll quality packet voice services. The advanced traffic engineering provided by MPLS also allows carriers to offer, guarantee, and bill for different service level agreements for data services. Furthermore, MPLS and IP provide dynamic allocation of unused bandwidth so that carriers can maximize the revenue generating potential of their networks.

MPLS World News: Supposedly this type of deployment will enable service providers to guarantee QoS levels (especially for voice and video), to dynamically allocate bandwidth or to improve billing procedures. Do any applications exist today justifying this "all-MPLS" strategy?

Guy Chenard: Yes, Integral Access customers deploying the IP/MPLS-based PurePacket system are currently delivering IP-based voice services, plus committed information rate data services over a single T1, E1, or DSL line to business customers. Typical applications currently in production using the PurePacket platform include integrated access services over a DSL line that include up to 24 voice lines, and 500 Kb of committed information rate data. When phones are not in use, the data will burst up to the full 1.5MB/s capacity of the line. Metro based VLANs and VPNs as well as multi-link broadband data are also emerging as key applications.

MPLS World News: How does MPLS fit into your distribution scheme?

Guy Chenard: The PurePacket system packetizes all traffic at the customer premise, and uses MPLS to manage voice call quality, and create differentiated service levels for data applications. For example, PurePacket uses MPLS to give real-time applications like voice and video priority in the network, and assign different service contracts to data traffic. PurePacket and its MPLS architecture enable carriers to offer and bill for several grades of data services such as constant bit rate for mission critical applications, and best effort for Internet access.

MPLS World News: Could you describe the architecture in place (between PurePacketNode, Outburst-Vx, Outburst Dx…)? What MPLS mechanisms are implemented on this equipment?

Guy Chenard: In a PurePacket network, carriers deploy OUTburst Integrated Access Devices (IADs) at the customer premise. These IADs support POTS lines, IP phones, PBXes, Centrex systems, and Key systems for voice; and routers for data and video codex. The OUTburst IADs packetize analog voice traffic and use MPLS to assign a label to each traffic stream that maps to its specific service level agreement. Label Switched Paths are then created from the customer premise-located OUTburst to a PurePacketNode aggregation gateway. The PurePacketNode can sit in the basement of a Multi Tenant Building (MTU), Point of Presence (PoP), or Central Office (CO). The PurePacketNode located at the CO then sends voice traffic to a Class 5 switch via the GR-303 interface, or to a managed IP network under SoftSwitch control as VoIP using MGCP or H.248. Data traffic is typically delivered to an Internet router.

MPLS World News: What is the signification of the recently signed agreement with Unisphere Networks? How does this incorporate into your development strategy?

Guy Chenard: The interoperability and marketing agreement between Integral Access and Unisphere Networks leverages MPLS to provide a complete network solution based on the PurePacket system and the Unisphere Intelligent Service POP. This combined solution uses MPLS to assure service quality levels for voice and data traffic from the customer premise and across core networks, to their ultimate destination. By using MPLS to distribute network intelligence, such as QoS, to the customer premises, this joint solution enables the reliable delivery of real time IP services including voice and video, as well as differentiated data services with separate service level agreements. Both our product lines support MPLS traffic management for IP services, and Integral Access' solution addresses small to medium businesses and SOHO customers, it was a natural extension to Unisphere's offering.

MPLS World News: Is there a move toward end-to-end IP/MPLS solutions?

Guy Chenard: Yes. MPLS is widely deployed by carriers for IP traffic engineering and to deliver VPN services. MPLS based VPNs typically cost less than traditional Frame Relay or leased line VPNs. It is a natural evolution for carriers to extend this same IP/MPLS architecture across the access network to the customer premise. Placing an ATM access network between the IP dominated customer premise, and the IP core, increases the complexity and costs of network management. In addition, end-to-end IP/MPLS infrastructures will enable truly manageable service level agreements.

MPLS World News: Are normalization bodies working on standardizing MPLS implementation in access equipment? Do standards already exist?

Guy Chenard: Yes. Standardization efforts are under way for transporting existing services, such as ATM, Frame Relay and leased line, over MPLS-based equipment including access equipment. Meanwhile, the VoMPLS standard is the first step in working towards specific MPLS applications for the access network. Also, the MPLS protocol used in the access network conforms to the same standards used by MPLS at the edge and in core networks. The key difference here is that the IP QoS implementation used in access networks requires a more stringent and granular QoS method than is typically used in core networks.

MPLS World News: What level of interoperability exists between competing equipment?

Guy Chenard: Since the ratified MPLS standard is fairly new, interoperability between competing equipment is still evolving. It will take some time for vendors to conform with the new standards. However, we are seeing interoperability initiatives now picking up momentum.

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