The rapid growth in bandwidth required to support video and broadband wireless is straining communication networks. The current 10-Gbit OTN infrastructure is facing bandwidth exhaustion as the channels approach their maximum capacity. Faced with higher capital expenditure, higher operating expenditure, and shrinking revenue growth, service providers are turning to 100-Gbit OTN solutions to scale their current 10-Gbit-based networks by a factor of ten. However, there are large numbers of legacy OTN, SONET, Ethernet, and storage systems operating at lower data rates, which need to be plugged into the emerging optical infrastructure using 100-Gbit OTN muxponders. Altera’s Stratix V FPGA family contains a number of key innovations that directly address the needs of 100-Gbit OTN muxponder solutions.

Introduction

The explosive demand for bandwidth in the metro and long-haul networking space is forcing service providers to find ways to utilize their wavelength division multiplexing (WDM) networks more efficiently. Figure 1 shows the increasing services and bandwidth demands being made of today’s Optical Transport Network (OTN) infrastructure.

Figure 1. Demands Being Made of Today’s OTN Infrastructure
 

This demand for ever-increasing bandwidth is driven by endless new applications such as peer-to-peer sharing, social networking, digital video transmission, broadband wireless handsets and video conferencing and messaging. In the past, service providers have attempted to keep up with this growth by simply adding more channels to their existing WDM networks, as shown in Figure 2. However, this scheme exhausted the available channels, leaving service providers to face higher capital expenditure, higher operating expenditure, and shrinking revenue growth. The reality is that conventional 10-Gbit OTN architectures do not facilitate cost-effective implementations that optimize bandwidth usage in greenfield deployments.

Figure 2. Traditionally, Service Providers Added More Channels as Bandwidth Demands Increased
 

With the introduction and adoption of 40-/100-Gbit Ethernet, and the acceptance of OTN standards, service providers are now turning to 100-Gbit OTN solutions to scale their channel capacity by a factor of ten. However, there are a large number of legacy OTN, SONET, Ethernet, and storage systems operating at lower data rates, which somehow must be connected into the emerging OTN infrastructure. One way to achieve this, in a way that maximizes the available bandwidth while reducing space and power, is to aggregate multiple lower data-rate client channels onto a single wavelength at a higher data rate. This is the role of the 100-Gbit OTN multiplexing transponder (muxponder).

100-Gbit OTN Muxponder Solution

Traditionally, OTN systems have line cards that interface with one or more client ports and aggregate them to an optical transport port. Each line card is designed to meet the requirements of a particular client protocol, and specific client and transport data rates. In an environment where there are many different client port types, many different line cards are required in each chassis. This is not a cost-, area-, power-, or management-efficient solution, and results in the individual client payloads being transported on different wavelengths, which reduces the overall efficiency of the fiber-optic cable.

Author:  Allan Davidson, Sr. Product Marketing Manager, High-End FPGA Products, Altera Corporation