using and offering wholesale ethernet networks and …€¦ · ·...

White Paper – Using and Offering Wholesale Ethernet

May 2013 | Rev 1.2

Using & Offering Wholesale Ethernet Network and Operational Considerations Introduction

Business services customers are continuing to migrate to Carrier Ethernet connections. Initially enterprises were attracted by the low cost per-‐bit – an effective way to address growing bandwidth requirements for increased volumes of email, Internet, storage and other best-‐effort applications. With real-‐time communications, transactional and other business critical applications are also moving to these wide area networks (WANs), Ethernet must now deliver more than just cheap bandwidth; services are increasingly backed by service level agreements (SLAs) that specify strict performance criteria including one-‐way delay, jitter, packet loss, guaranteed throughput and availability – often on a per-‐application basis.

In addition to these new performance demands, enterprises evaluating Ethernet service providers also require comprehensive geographic coverage. They seek to connect as many of their remote sites as possible with a single service provider. This simplifies accountability, billing, and support for the IT professionals maintaining the WAN. As a result, service providers need to provide ubiquitous Ethernet to successfully win business from large enterprise, government, educational, media and legal institutions.

As few providers have a network that reaches all customer sites, providers need access to affordable, performance-‐assured Ethernet wholesale – to bridge geographically diverse on-‐net markets, and to provide last-‐mile access to off-‐net locations. From an operators’ perspective, this results in two opportunities:

1-‐ offering Ethernet wholesale over their network as a new, revenue-‐driving service,

2-‐ using Ethernet wholesale from other providers to cost-‐effectively expand service offerings to off-‐net locations.

Hand-‐offs: Gateway to Ethernet Wholesale

Wholesale hand-‐offs happen whenever packets hop networks, from one provider to another, or from a providers network to their end-‐customers’. How hand-‐offs are handled has a significant impact on quality of service (QoS), interconnection simplicity, and end-‐to-‐end management.

Wholesale Ethernet must be transparent from a service perspective. It needs to carry multiple-‐VLANs, support point-‐to-‐point, hub-‐and-‐spoke, unicast and multicast applications, and ensure timely transport for IP-‐layer signaling for video and conferencing sessions.

White Paper – Using and Offering Wholesale Ethernet | May 2013 | Rev 1.2

When multiple off-‐net locations connect to each other, full-‐mesh performance must also be maintained between all endpoints.

Hand-‐offs also serve as demarcation points where circuit performance and SLAs are measured. SLAs are central to wholesale opportunities: service providers need performance assurance from wholesale operators (provider-‐to-‐provider SLAs) to ensure that they, in turn, can maintain end-‐to-‐end QoS to their end-‐customers (provider-‐to-‐enterprise SLAs).

As a result, wholesale applications need standards-‐based, low-‐latency hand-‐offs between networks. QoS needs to be established, maintained and monitored directly at these hand-‐off locations in order to meet strict SLAs. Furthermore, service providers need on-‐net visibility for off-‐net locations to enable and assure end-‐to-‐end performance.

Requirements for Effective Ethernet Wholesale

Peering Carrier Ethernet networks require standards-‐based functionality for service creation, transport and operations, administration & maintenance (OAM).

MEF Carrier Ethernet Service Mapping

At the most basic level, equipment terminating a wholesale circuit needs to be MEF certified. Service mapping standards ensure consistent Ethernet service creation and transparency by specifying the VLAN tagging methods used to establish E-‐Line, E-‐Tree and ELAN services. The standards also specify how to establish and enforce a circuits bandwidth profile; rate limiting maintains committed and excess information rates and burst allowances (CIR, EIR, CBS, EBS). Finally, EVCs need to be prioritized with the appropriate class of service (CoS) as recorded in the VLAN header. Ideally, all of these packet-‐handling functions are performed by the network element within microseconds, since adding latency and jitter to traffic can make SLAs difficult to maintain, especially over long routes where multiple hand-‐offs and aggregation points each introduce incremental delay over the end-‐to-‐end path.

Key Ethernet Wholesale Hand-‐Off Points & SLAs


Beyond just creating the service itself, performance needs to be maintained on a per-‐VLAN or per-‐application basis to ensure consistent circuit performance, as network congestion and routing may impact certain services more than others between hand-‐off points. These locations, book-‐ending the wholesale segments of the network, are a natural point to groom traffic to (re)establish flow priorities and bandwidth allowances. They are the first and last points of control for a provider using, or offering, Ethernet wholesale services.

To effectively maintain QoS with potentially hundreds of flows converging upon a hand-‐off location, equipment needs to support hierarchical QoS (H-‐QoS) functionality: the ability to (re)prioritize certain packets, applications or flows over others before forwarding into a wholesale link with limited (and often oversubscribed) capacity. Implemented properly, H-‐QoS ensures that SLAs for all critical services are met, while maintaining the best possible performance for all traffic types passing through a hand-‐off.

Ethernet Service Mapping (VLAN and CoS tagging)

From a traffic management perspective, H-‐QoS is best established using a combination of bandwidth policing and traffic shaping. Whereas bandwidth policing (rate limiting) simply discards packets when bandwidth is unavailable and shaping tries to minimize packet loss through selective, priority-‐based buffering. When configured to work in concert by using a per-‐flow hierarchy, these technologies can dramatically increase bandwidth efficiency, accelerate critical and real-‐time applications, and reduce packet-‐loss and the overhead which retransmission creates.

When performing traffic conditioning at hand-‐off points, packet-‐processing speed is critical. It’s important that priority flows experience near-‐zero delay or jitter, regardless of the traffic volume being processed at the hand-‐off or the number of flows in the hierarchy.


Points to establish and maintain H-‐QoS

OAM Considerations

Ethernet OAM is a fundamental component of offering and using Ethernet wholesale services. The ITU-‐T Y.1731 and IEEE 802.1ag standards for connectivity fault management (CFM) and performance monitoring (PM) were designed with Ethernet interconnection in mind, thereby designed to simplify the management of multi-‐operator and multi-‐vendor networks. As a multi-‐layer model, service providers using an operator for Ethernet wholesale are notified when faults occur in the operators’ network, allowing them to reroute traffic if required. Detailed OAM messages are visible to service providers only where they are responsible for the service, simplifying troubleshooting while limiting visibility to customers. Ethernet OAM gives each carrier the information they need to run their section of the overall circuit, while continuity and performance measurements pass transparently from end-‐to-‐end.

Multi-‐Domain, Ethernet OAM Model employed by Y.1731 & 802.1ag

Inter-‐provider hand-‐off points carry significant volumes of traffic, so equipment needs to be able to maintain a large number of concurrent OAM sessions. Running one OAM session per-‐port is insufficient as each VLAN, or flow, needs to be individually monitored to assure SLAs. Providers offering or using Ethernet wholesale need to plan for up to 100 OAM sessions per GbE port, and up to 1,000 for a 10GbE hand-‐off.

In addition to the number of sessions supported, it is important that CFM sessions can be established with up to per-‐second frequency to assure 99.999%


availability. From a QoS monitoring perspective, Performance Monitoring packets need to be time-‐stamped and processed precisely –typical SLAs require sub-‐millisecond resolution one-‐way delay and jitter measurements.

Key Ethernet OAM CFM & PM Features

SLAs: The Language of Wholesale

There’s no doubt that Service Level Agreements are the language of wholesale, and that monitoring is the currency that ensures providers deliver SLA commitments. Both end-‐customers and service providers using wholesale are increasingly demanding real-‐time, web-‐based reporting portals so they can check up on service performance. Monitoring is especially critical for Ethernet services, which lack the circuit-‐switched, dedicated bandwidth of TDM-‐based communications, and often get carried over multi-‐technology, multi-‐protocol and multi-‐vendor networks that are frequently oversubscribed.

While Ethernet OAM is a basic requirement for interconnection and efficient service management, in many cases it is not adequate to monitor SLAs and provide comprehensive service assurance; network element vendors often implement OAM features in software running on shared network processors, prioritized to perform switching, routing and traffic management functions. This limits measurement precision, the number of supported flows, and the frequency of CFM packets. In addition, interoperability issues between vendors are common, especially where features are not fully implemented. Another important limitation of Ethernet OAM is that it only works at Layer 2 –it offers no IP-‐layer performance monitoring or fault visibility, and OAM packets are often dropped when they hit


routed, MPLS networks (as pure Ethernet frames with only MAC addresses). This prevents OAM from providing an end-‐to-‐end view over many networks, and leaves IP-‐layer applications and SLAs un-‐assured over a typical wholesale-‐enabled circuit.

Using NIDs and E-‐NNIUs to Deploy and Use Ethernet Wholesale

A practical way to introduce Ethernet wholesale into existing networks is to deploy Ethernet Network-‐to-‐Network Interface Units (E-‐NNIU) at inter-‐carrier hand-‐offs and Network Interface Devices (NIDs) at customer premises. These cost-‐efficient, hardware-‐based units provide continuous Ethernet & IP performance monitoring, Ethernet OAM, and high performance MEF service mapping and traffic shaping functionality at a fraction of the cost of a typical switch. With the ability to handle up to 100 flows per unit, a provider can deliver fully assured Ethernet services over existing networks, and easily maintain the performance of full mesh and multicast applications to off-‐net locations.

By using NIDs and NNIUs as a uniform service delivery point to connect to carriers and customers, a provider simplifies deployment and management of services by maintaining them all from a common platform. A centralized monitoring system collecting statistics in real-‐time and from all hand-‐off points, provides the end-‐to-‐end visibility and web-‐based reporting required to satisfy customer SLAs requirements.

E-‐NNIUs, NIDs and a centralized monitoring platform deployed to establish Ethernet wholesale over an existing network

Accedian Networks’ Solution for Ethernet Wholesale

Performance Assured Networking Solutions

Accedian Networks is a leading provider of network interface devices for business services, wireless backhaul, and Ethernet wholesale applications. The MetroNID family of Performance Assured Networking solutions combine all the functionality required to deliver service performance with assurance™ as E-‐NNIUs and customer-‐located NIDs. These units offer a full range of Service Assurance features, including advanced loopback testing, Layer 2 and Layer 3 continuous monitoring, the full suite of Ethernet OAM, and support for existing test sets. Accedian solutions also contain advanced service creation features including


service mapping, traffic shaping, switch-‐free aggregation and advanced H-‐QoS functionality.

Also key to hand-‐off applications, these devices are NEBS Level 3 certified, consume only several watts of power, and feature proven, industry-‐leading reliability and complete network and client-‐side circuit protection.

Combined Service Assurance and Service Creation of the Accedian Solutions

Carrier-‐Grade EMS and Monitoring Platforms

Accedian Networks also offers a purpose built EMS solution: The Accedian Networks Vision product suite simplifies service assurance and management. The Vision EMS™, Next Generation Element Management System, provides device configuration and management, performance data collection and workflow automation capabilities. The flexible and easy to use VisionMETRIX™ is a Performance and SLA Monitoring tool which provides true end-‐to-‐end IP circuit and network visibility, i.e. an end-‐to-‐end holistic view of circuit health. All of these tools are easy to deploy and integrate within network operators’ existing infrastructure.

To learn more about Accedian Performance Assured Networking™ solutions for Wholesale Ethernet, please visit: www.accedian.com.

© 2013 Accedian Networks Inc. All rights reserved. Accedian Networks, the Accedian Networks logo, High Performance Service Assurance, Performance Assurance Agent, NanoNID, MetroNID, EtherNID, MetroNODE 10GE, Fast-‐PAAs, PAA, SLA-‐Meter, Plug & Go, Multi-‐SLA, Traffic-‐Meter, Vision EMS, VisionMETRIX and V-‐NID are trademarks or registered trademarks of Accedian Networks Inc. All other company and product names may be trademarks of the respective companies. Accedian Networks may, from time to time, make changes to the products or specifications contained herein without notice. Some certifications may be pending final approval, please contact Accedian Networks for current certifications.

Accedian Networks Inc.

2351 Alfred-‐Nobel, Suite N-‐410

St-‐Laurent (Montreal), Quebec, Canada H4S 2A9

Toll free: 1-‐866-‐685-‐8181

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