Customer Corner: Intergrating an Intelligent Optical Layer into the Internet
Manageing cut-through optical paths
The CTVR at Trinity College Dublin is developing an innovative, intelligent, high capacity network to prove the economic benefits of cut-through optical paths over the purely router-based networks in common use today.
CTVR OVERVIEW
Trinity College in Dublin is headquarters for the Center for Telecommunications Value-Chain Research Center (CTVR). Funded by the Science Foundation Ireland (SFI), Ireland’s Industrial Development Agency (IDA) and Lucent Technologies' Bell Labs, the CTVR is part of a national initiative designed to empower telecommunications research. The Center uniquely focuses on the reliable manufacture and construction of innovative network designs. Bringing together a multidisciplinary team of researchers, the center applies value chain perspectives to the entire life cycle of network product development with the belief that while future networks may be shaped through technical innovation, such networks are only practical if affordable and reliable.
CUT-THROUGH NETWORKS
The CTVR is developing an innovative, intelligent, high capacity network to prove the economic benefits of cut-through networking over the purely router-based networks in common use today. CTVR also believes that its network design will better enable the connection among a global network of small to medium-sized network providers.
The CTVR group opted to create a distributed and disaggregated network using “cut-through” paths. While some existing research-oriented, high bandwidth networks do provide end-to-end dedicated wavelengths using optical technology, most global point-to-point data paths are disaggregated, requiring routing through several competing networks. Each routing juncture adds cost and complexity.
By using a distributed/disaggregated system, paths will be automatically and dynamically provisioned based on the traffic flows encountered at a specific router. For example, each time an end node detects a higher volume of traffic going to a particular destination it can automatically create a “cut-through” path through the network for that particular packet flow.
This method minimizes expensive packet-handling at core routers, yielding significantly improved performance for both applications and networks. It is also less complex and costly in that local nodes can make decisions resulting in better global results. Critical to the operation of such a system is the use of high port-count, optical switches to enable high speed, dynamic light path switching.
CTVR IMPLEMENTATION
The CTVR team needed several high port count optical switches to more easily enable direct and easy access to the switching elements. Specifically, CTVR wanted switches with these requirements:
- A simple interface - “We wanted a simple interface from which we could access the switch at a low level using an industry standard TL1 protocol,” said Prof. Donald O’Mahony, leader of the Networks & Telecommunications Research Group at Trinity College.
- Speed - Speed of actuation was another important selection criterion. The faster an optical path can be established, the shorter the packet flow needs to be to make the exercise worthwhile.
- Dark fiber - The team also needed a switch that could actuate the switching elements prior to the presence of light at the source.
CTVR selected the Glimmerglass Intelligent Optical Switch based on superior performance in these three areas.
Initially the Center created a dedicated wavelength between Trinity College and Dublin City University using facilities provided by HEAnet, Ireland’s national networking research organization. Next, the team added an additional two wavelengths to carry heavy flows detected within the existing traffic. Currently, researchers are developing and testing protocols, algorithms, etc. designed to recognize flows that are likely to be long-lived, predict them accurately and then automatically allocate wavelengths to these elephant flows.
WHAT NEXT?
In the near-term, work continues to create a fully-functioning network operating with this core concept. The CTVR team plans to expand its focus to include label switching and in particular optical subcarrier labels. The latter involves sending the label data on a separate subcarrier to the payload data, allowing the payload to remain in the optical domain throughout the entire network. The team also plans to further explore wavelength converters to reduce path contention.
