ONF’s operators seize control of their networking needs
- The eight ONF service providers will develop reference designs addressing the network edge.
- The service providers want to spur the deployment of open-source designs after becoming frustrated with the systems vendors failing to deliver what they need.
- The reference designs will be up and running before year-end.
- New partners have committed to join since the consortium announced its strategic plan
The service providers leading the Open Networking Foundation (ONF) will publish open designs to address next-generation networking needs.
Timon SloaneThe ONF service providers - NTT Group, AT&T, Telefonica, Deutsche Telekom, Comcast, China Unicom, Turk Telekom and Google - are taking a hands-on approach to the design of their networks after becoming frustrated with what they perceive as foot-dragging by the systems vendors.
“All eight [operators] have come together to say in unison that they are going to work inside the ONF to craft explicit plans - blueprints - for the industry for how to deploy open-source-based solutions,” says Timon Sloane, vice president of marketing and ecosystem at the ONF.
The open-source organisation will develop ‘reference designs’ based on open-source components for the network edge. The reference designs will address developments such as 5G and multi-access edge and will be implemented using cloud, white box, network functions virtualisation (NFV) and software-defined networking (SDN) technologies.
By issuing the designs and committing to deploy them, the operators want to attract select systems vendors that will work with them to fulfil their networking needs.
Remit
The ONF is known for such open-source projects as the Central Office Rearchitected as a Datacenter (CORD) and the Open Networking Operating System (ONOS) SDN controller.
The ONF’s scope has broadened over the years, reflecting the evolving needs of its operator members. The organisation’s remit is to reinvent the network edge. “To apply the best of SDN, NFV and cloud technologies to enable not just raw connectivity but also the delivery of services and applications at the edge,” says Sloane.
The network edge spans from the central office to the cellular tower and includes the emerging edge cloud that extends the ‘edge’ to such developments as the connected car and drones.
The operators have been hopeful the whole vendor community would step up and start building solutions and embracing this approach but it is not happening at the speed operators want, demand and need
“The edge cloud is called a lot of different things right now: multi-access edge computing, fog computing, far edge and distributed cloud,” says Sloane. “It hasn’t solidified yet.”
One ONF open-source project is the Open and Disaggregated Transport Network (ODTN), led by NTT. “ODTN is edge related but not exclusively so,” says Sloane. “It is starting off with a data centre interconnect focus but you should think of it as CORD-to-WAN connectivity.”
The ONF’s operators spent months formulated the initiative, dubbed the Strategic Plan, after growing frustrated with a supply chain that has failed to deliver the open-source solutions they need. “The operators have been hopeful the whole vendor community would step up and start building solutions and embracing this approach but it is not happening at the speed operators want, demand and need,” says Sloane.
The ONF’s initiative signals to the industry that the operators are shifting their spending to open-source solutions and basing their procurement decisions on the reference designs they produce.
“It is a clear sign to the industry that things are shifting,” says Sloane. “The longer you sit on the sidelines and wait and see what happens, the more likely you are to lose your position in the industry.”
If operators adopt open-source software and use white boxes based on merchant silicon, how will systems vendors produce differentiated solutions?
“All this goes to show why this is disruptive and creating turbulence in the industry,” says Sloane.
Open-source design equates to industry collaboration to develop shared, non-differentiated infrastructure, he says. That means system vendors can focus their R&D tackling new issues such as running and automating networks, developing applications and solving challenges such as next-generation radio access and radio spectrum management.
“We want people to move with the mark,” says Sloane. “It is not just building a legacy business based on what used to be unique and expecting to build that into the future.”
Reference designs
The operators have identified five reference designs: fixed and mobile broadband, multi-access edge, leaf-and-spine architectures, 5G at the edge, and next-generation SDN.
The ONF has already done much work in fixed and mobile broadband with its residential and mobile CORD projects. Multi-access edge refers to developing one network to serve all types of customers simultaneously, using cloud techniques to shift networking resources dynamically as needed.
At first glance, it is unclear what the ONF can contribute to leaf-and-spine architectures. But the ONF is developing SDN-controlled switch fabric that can perform advanced packet processing, not just packet forwarding.
The ONF’s initiative signals to the industry that the operators are shifting their spending to open-source solutions and basing their procurement decisions on the reference designs they produce.
Sloane says that many virtualised tasks today are run on server blades using processors based on the x86 instruction set. But offloading packet processing tasks to programmable switch chips - referred to as networking fabric - can significantly benefit the price-performance achieved.
“We can leverage [the] P4 [programming language for data forwarding] and start to do things people never envisaged being done in a fabric,” says Sloane, adding that the organisation overseeing P4 is going to merge with the ONF.
The 5G reference design is one application where such a switch fabric will play a role. The ONF is working on implementing 5G network core functions and features such as network slicing, using the P4 language to run core tasks on intelligent fabric.
The ONF has already done work separating the radio access network (RAN) controller from radio frequency equipment and aims to use SDN to control a pool of resources and make intelligent decisions about the placement of subscribers, workloads and how the available radio spectrum can best be used.
The ONF’s fifth reference design addresses next-generation SDN and will use work that Google has developed and is contributing to the ONF.
The ONF manages the OpenFlow protocol, used to define the separation between the control and data forwarding planes. But the ONF is the first to admit that OpenFlow overlooked such issues as equipment configuration and operational issues.
The ONF is now engaged in a next-generation SDN initiative. “We are taking a step back and looking at the whole problem, to address all the pieces that didn’t get resolved in the past,” says Sloane.
Google has also contributed two interfaces that allow device management and the ONF has started its Stratum project that will develop an open-source solution for white boxes to expose these interfaces. This software residing on the white box has no control intelligence and does not make any packet-forwarding decisions. That will be done by the SDN controller that talks to the white box via these interfaces. Accordingly, the ONF is updating its ONOS controller to use these new interfaces.
Source: ONF
From reference designs to deployment
The ONF has a clear process to transition its reference designs to solutions ready for network deployment.
The reference designs will be produced by the eight operators working with other ONF partners. “The reference design is to help others in the industry to understand where you might choose to swap in another open source piece or put in a commercial piece,” says Sloane.
This explains how the components are linked to the reference design (see diagram above). The ONF also includes the concept of the exemplar platform, the specific implementation of the reference design. “We have seen that there is tremendous value in having an open platform, something like Residential CORD,” says Sloane. “That really is what the exemplar platform is.”
The ONF says there will be one exemplar platform for each reference design but operators will be able to pick particular components for their implementations. The exemplar platform will inevitably also need to interface to a network management and orchestration platform such as the Linux Foundation’s Open Network Automation Platform (ONAP) or ETSI’s Open Source MANO (OSM).
The process of refining the reference design and honing the exemplar platform built using specific components is inevitably iterative but once completed, the operators will have a solution to test, trial and, ultimately, deploy.
The ONF says that since announcing the strategic plan a month ago, several new partners - as yet unannounced - have committed to join.
“The intention is to have the reference designs up and running before the end of the year,” says Sloane.
OFC 2016: a sample of the technical paper highlights
Here is a small sample of the technical paper highlights being presented at the conference.
Doubling core network capacity
Microsoft has conducted a study measuring the performance of its North American core backbone network to determine how the use of bandwidth-variable transceivers (BVTs) could boost capacity.
The highest capacity modulation scheme suited for each link from the choice of polarisation-multiplexed, quadrature phase-shift keying (PM-QPSK), polarisation-multiplexed, 8 quadrature amplitude modulation (PM-8QAM) and PM-16QAM can then be used.
By measuring the signal (Q-factor) for all its PM-QPSK based 100 gigabit links, Microsoft's study found that network capacity could be increased by 70 percent using BVTs. Equally, having the ability to increase capacity in 25-gigabit increments would increase capacity by a further 16 percent while a finer resolution of 1-gigabit would add an extra 13 percent.
Microsoft says such tuning of links need not be done in real time but rather when a link is commissioned or undergoing maintenance.
[paper M2J.2]
Architecting a new metro
How can operators redesign their metro network to enable rapid service innovation? This is the subject of a joint paper from AT&T, the Open Networking Lab and Stanford University. The work is part of a programme dubbed CORD to redesign the central office as a data centre using commodity hardware and open software to enable the rapid scaling of services. In particular, OpenFlow-enabled white boxes, the Open Network Operating System (ONOS) - a software-defined networking (SDN) operating system, and network control and management applications are used.
As part of CORD, three legacy telecom devices - optical line termination (OLT), customer premises equipment (CPE), and broadband network gateways (BNG) - have been virtualised and implemented on servers.
The paper details how a single SDN control plane based on ONOS is used to create a converged packet-optical metro network and how its support for bandwidth on-demand and automatic restoration at the optical level is used for enterprise connectivity and video distribution services.
The paper also discusses how the metro architecture supports 'disaggregated' reconfigurable optical add/ drop multiplexers (ROADMs). By disaggregating a chassis-based ROADM into commodity components, an operator can size its infrastructure as required and grow it with demand, the paper says.
[paper Th1A.7]
400 gigabit single-carrier transmission
Nokia Bell Labs reports work on 400 gigabit-per-second (Gbps) single-carrier optical transmission over submarine distances. The attraction of adopting 400 gigabit single-carrier transmission as that it is the most efficient way to reduce the cost-per-bit of optical transmission systems.
The Bell Labs' paper reviews state-of-the-art 400 gigabit single-channel transmissions over 6,000km and greater distances, and discusses the tradeoffs between such variables as symbol rate, modulation and forward error correction (FEC) schemes.
400Gbps single-carrier submarine transmission is likely in the next few years
PM-16QAM is proposed as a promising modulation scheme to achieve beyond 6,000km distances and a spectral efficiency exceeding 5b/s/Hz. But this requires a symbol rate of greater than 60 gigabaud to accommodate the 20 percent overhead FEC. Pulse-shaping at the transmitter is also used.
Exploring the receiver performance with the varying symbol rate/ FEC overhead, Bell Labs reports that the best tradeoff between coding gain and implementation penalties is 64 gigabaud and 27.3% overhead. It concludes that single-carrier 400Gbps submarine transmission is likely in the next few years.
[paper Th1B.4]
Silicon modulator for CFP2-ACOs
Cisco has developed a compact flip-chip assembly that combines a silicon photonics modulator and a silicon germanium BiCMOS Mach-Zehnder modulator driver. Such an assembly forms the basis for low-cost advanced coherent optical transceivers such as the CFP2-ACO.
Cisco has demonstrated the assembly operating at 128.7Gbps using PM-QPSK and 257.3Gbps using PM-16QAM. Cisco believes this is the first demonstration of transmission at 257.3Gbps using PM-16QAM over 1,200km of standard single-mode fibre using a silicon photonics-based device.
The modulator has also been demonstrated operating at 321.4Gbps using PM-16QAM transmission and a 20 percent FEC overhead, the highest bit rate yet achieved using a silicon-photonics based transmitter, claims Cisco.
Cisco is already using CFP2-ACO modules as part of its NCS 1002 data centre interconnect platform that implement PM-16QAM and deliver 250 gigabit due to the use of a higher baud rate than the 32 gigabaud used for existing 100-gigabit coherent systems.
[paper Th1F.2]
Flexible Ethernet to exploit line-side efficiencies
Given how the optical network network is starting to use adaptive-rate interfaces, a paper from Google asks how the client side can benefit from such line-side flexibility.
The paper points out that traditional DWDM transport equipment typically multiplexes lower-rate client ports but that this doesn't apply to network operators that manage their own data centres. Here, traffic is exclusively packet-based from IP routers and typically matches the line rate. This is why data centre interconnect platforms have become popular as they require limited grooming capability.
Google highlights how Flexible Ethernet (FlexE), for which the Optical Internetworking Forum has just defined an Implementation Agreement for, combined with data centre interconnect equipment is an extremely effective combination.
FlexE supports Ethernet MAC rates independent of the Ethernet physical layer rate being used. Google shows examples of how using FlexE, sub client rates can match the line-side rate as well as how multiple client ports can support a higher speed router logical port.
The paper concludes that combining FlexE with data centre interconnect results in a low cost, low power, compact design that will enable Internet content providers to scale their networks.
[paper W4G.4]