Network Systems DesignLine | Opt for a smooth transition to Provider Backbone Transport (PBT)--Part II

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HOW-TO : Ethernet Design

Opt for a smooth transition to Provider Backbone Transport (PBT)--Part II

By Peter Lunk, Extreme Networks

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Network Systems Designline
(03/07/2007 1:03 AM EST)

A smooth transition to PBT
It is anticipated that PBT technology could reach the IEEE sponsor ballot phase by summer of 2008. At that point, major technology changes are unlikely to occur, and the essentials of the standard will effectively be set in place. Key industry players are already shipping the building block technologies required to support PBT and are planning on interoperability testing later this year so that products can be ready for delivery in 2008.

Part of the strategy that will enable existing products deployed in networks today to support PBT is to partition functionality between hardware and software in such a way that PBT, once it is available, can be implemented entirely as a software upgrade. Provider Backbone Bridges support is expected to be a key hardware limiter for the deployment of PBT, and as a result, PBB support should be an important purchase criteria for those providers deploying Ethernet switches today. Without PBB support, a migration to PBT will be much more difficult.

Implementing PBB today as a foundation for upgrading to PBT also provides immediate benefits to carriers. By itself, PBB technology alleviates scalability issues within the metro core. Additionally, experience with operating PBB capabilities directly correlates with the transition to PBT since many of the network operations will remain the same. Switches supporting 802.1ah PBB and 802.1ag Ethernet CFM are available today and have been proven in real-world networks.

Another key factor in the migration to PBT is the ability to divide the PBB VLAN ID space to support both learned PBB and provisioned PBT routes side-by-side. Rather than having to turn off all PBB based services and re-provision them to PBT, carriers can simply turn on new services with PBT. This enables carriers to make a gradual transition to PBT, without having to disrupt existing subscriber services.

Because PBT is built on emerging Ethernet technologies, carriers can take immediate advantage of the benefits these technologies offer while preparing their networks for a smooth, software-only upgrade to PBT that also enables them to control the transition of subscribers from PBB to PBT. Finally, by adding PBT to a network that supports service resiliency and E-NNI capabilities, carriers will benefit from enhanced service reach and a reliable service delivery for their subscribers, all while maintaining a familiar operational model.

About the Author
Peter Lunk is the Director of Service Provider Marketing at Extreme Networks. He can be reached at plunk@extremenetworks.com

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