Published on September 13, 2013
Full Speed Ahead for OTN
In today’s high-speed core network market, more and more network operators are being forced to deploy high-speed Optical Transport Networks (OTN) in response to increased demand for higher bandwidth. It is not surprising that, according to Infonetics’ OTN and Packet Optical Hardware report, it is one of the fastest-growing segments of the optical market, making up nearly half of all 2011 optical equipment spending.
OTN offer efficient traffic grooming and optimal granularity through virtual containers such as ODU0, which in turn offer ideal support for packet-based services like Ethernet and Fibre Channel. As per TDM networks with SONET and SDH, OTN also offer a protection-switching mechanism that switches all traffic from the working path to the protection path in the event of failure.
Most large carrier networks have aggregation switches (see Figure 1) deployed at major gateway locations. This offers several key benefits, as described below:
- OTN switches operating at the OTU layer. These switches are independent of the traffic type carried within the payload, which means that the network becomes transparent to any underlying services and protocols.
- Switching at the ODU layer, which maintains the end-to-end optical performance and alarm monitoring.
- OTN switching utilizing standard OTN mapping structures, which allows for efficient grooming of traffic and high utilization of the ultra-longhaul (ULH) wavelengths.
- Next-generation OTN switches, which offer ODU0 granularity and ensure switching time within the standard value.
The Multi-Channel Service Disruption Time (M-SDT) is a measurement feature that offers simultaneous duration measurement on all channels. Using advance triggers, it measures the transition of all channels from the working to the protection path to ensure that the switching time is within the 50 ms window defined by the ITU G.841 standard. In today’s metro networks, the MESH configuration (Figure 2) is heavily used where OTN core network switches can cause delays, resulting in channels not all switching within the recommended time. It is essential that all channels can be viewed at the same time, and that the time of each channel can be measured. For more information about the OTN/SONET/SDH M-SDT approach, which is now available on EXFO’s FTB-81xx Transport Blazer family, read the Multi-Channel Service Disruption Time (M-SDT) application note.
If you are service provider, a cable company or a supplier looking to better understand the high-growth OTN market, register to Infonetics Research’s The OTN Expansion: The Next Carrier Upgrade Cycle webinar. This event will look at transport network deployment plans for the next five years and the role that OTN switching will play in this expansion.