With the data storm from cloud computing, mobility and streaming video pushing operators to the breaking point to meet demand, IP network scalability is essential.
Microwave technology has and will continue to provide much of the backend data transmission, but for modern packet microwave systems scalability is managed at the network level instead of on a link-by-link basis as was the case with older microwave technology.
One challenge that packet microwave brings is how to aggregate sites. The site aggregation device must have a low-delay, non-blocking, packet-based switching fabric with service-awareness to provide deterministic quality of service (QoS) to high-priority traffic in the microwave environment, as a recent Alcatel-Lucent (News - Alert) application note, Migrating TDM Services to Packet Networks, pointed out. At the same time, this site aggregation device must allow for TDM migration through the support of legacy TDM services that are still deployed in many networks.
The Circuit Emulation Services over Ethernet (CESoETH) standard was developed to meet this challenge of transporting TDM services over packet networks. But to make CESoETH work effectively over an end-to-end packet network requires additional technologies beyond the CESoETH standard.
What are needed to make CESoETH work efficiently are technologies to control packet delay variation (PDV), latency, traffic prioritization, and TDM circuit performance. Alcatel-Lucent’s 9500 Microwave Packet Radio (9500 MPR) highlights how this can be done.
Mixing different length over a microwave link introduces high PDV, which degrades the quality of real-time TDM services. The 9500 MPR controls and bounds PDV with a patented fragmentation and interleaving technique that fragments longer frames before placing them in queues.
The 9500 MPR addresses latency through bandwidth optimization addressed by a MEF (News - Alert) 8 optimization patent. The 9500 MPR service awareness identifies the MEF 8 frames to apply a patented technique that reduces the MEF 8 overhead before sending the MEF 8 Ethernet frames on the radio physical layer. This algorithm optimizes over-the-air bandwidth utilization.
The 9500 MPR also allows for flexible traffic prioritization, including setting aside the highest priority queues used for CESoETH, according to the Alcatel-Lucent application note. This prioritization guarantees that dedicated bandwidth is available for TDM services regardless of Ethernet congestion or frame size of other applications.
Finally, the 9500 MPR tackles TDM circuit performance through a Network Synchronization in an Ethernet World patent. The 9500 MPR supports patented microwave technology to transport a synchronization signal across a microwave radio link. The network clock is locked to the radio symbol rate (Layer 1), allowing a pair of 9500 MPR devices to relay a network-clock reference from one site over a microwave link to another site.
CESoETH can work, but it needs the right mix of technologies to support it.
Edited by Peter Bernstein