White Paper




    Multiservice Ethernet
Network Termination Units
                   The Need for Integrated TDM & LAN A...
Contents

Introduction ......................................................................................................
White Paper: Ethernet OAM




Introduction
As the benefits of Ethernet networking in the metro and wide-area have become c...
White Paper: Ethernet OAM




The following diagram provides an overview of these NTU capabilities.




The network interf...
White Paper: Ethernet OAM




tunneling, and to control the Tunnel P-bit (class of service) and ensure that service provid...
White Paper: Ethernet OAM




Substantial progress from recent standards activity promises widespread availability and
int...
White Paper: Ethernet OAM




Pseudo-Wire/Circuit Emulation
Once organizations begin using high bandwidth, low cost Ethern...
White Paper: Ethernet OAM




Among the challenges with pseudo-wire circuit emulation technology, regenerating accurate
cl...
White Paper: Ethernet OAM




Ethernet and TDM Service Delivery to Out-of-Footprint
Geographies
An example of where multis...
White Paper: Ethernet OAM




RAD Data Communications Solutions


                Table 1 – RAD Ethernet and TDM Services ...
White Paper: Ethernet OAM




Summary
With Ethernet services becoming the metropolitan – and ultimately wide area – access...
www.rad.com




                              Corporate Headquarters                       U.S. Headquarters
             ...
Upcoming SlideShare
Loading in...5
×

Multiservice Ethernet Network Termination Units

1,127

Published on

0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
1,127
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
26
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Transcript of "Multiservice Ethernet Network Termination Units"

  1. 1. White Paper Multiservice Ethernet Network Termination Units The Need for Integrated TDM & LAN Access over Ethernet Services By Yacov Cazes, Director of Ethernet Access Product Marketing RAD Data Communications Innovative Access Solutions
  2. 2. Contents Introduction .................................................................................................... 1 An NTU (Network Termination Unit) for Every Need ......................................... 1 The Importance of OAM................................................................................... 3 The Need to Support E1/T1 and E3/T3 Circuits ................................................. 4 Pseudo-Wire/Circuit Emulation ......................................................................... 5 Multiservice Ethernet Network Termination Units ............................................. 6 Ethernet and TDM Service Delivery to Out-of-Footprint Geographies................ 7 RAD Data Communications Solutions ............................................................... 8 Summary......................................................................................................... 9
  3. 3. White Paper: Ethernet OAM Introduction As the benefits of Ethernet networking in the metro and wide-area have become clear, service providers are lining up to meet the rapidly growing demand for Ethernet services. As with any mainstream telecommunications service, providers need a reliable way to deliver, control and maintain their offerings. Customers are selecting providers who can offer Service Level Agreements (SLAs) tied to a variety of service packages. This paper will explore the benefits multiservice network termination units offer in economical Ethernet service delivery, while supporting revenue-generating legacy TDM services. An NTU (Network Termination Unit) for Every Need A clear demarcation point between the service provider and customer network is a prerequisite for reliable service delivery and SLA management. As shown in the following diagram, the “demarc” serves as the formal dividing line for defining network ownership and responsibility. Service providers frequently prefer to own the termination equipment at the customer premises to ensure reliable service delivery at the formal hand-off to the customer. Customer Premises Service Provider Network NTU CPE Provider Customer Network Network Demarcation Point Figure 1 – Demarcation Point Network Termination Units can vary from very simple to sophisticated devices. If the service provider is delivering simple, “best effort” Ethernet service, a simple media converter that translates between the last mile fiber feed and the customer’s internal network may be sufficient. However, should the provider wish to have more control over the service, an intelligent Ethernet NTU (E-NTU) is necessary. Finally, if the customer also needs support for legacy TDM services over the Ethernet connection, a multiservice NTU is required. © 2006 RAD Data Communications Ltd. 1
  4. 4. White Paper: Ethernet OAM The following diagram provides an overview of these NTU capabilities. The network interface side of the NTU provides the physical termination of the service provider’s fiber loop. Fiber is typically used due to the distance that has to be covered between the customer and the closest POP, as well as the high data rates customers demand. It must have the flexibility to accommodate a variety of data rates, fiber modes and wavelengths to ensure scalable and economical service reach from short distances to dozens of miles. In addition, the network interface needs to support a variety of remote OAM functions for ensuring maximum up-time and eliminating costly “truck rolls” to diagnose and correct problems. These functions include remote diagnostic and loopback tests, fault propagation, inband and out-of-band management and remote software download and configuration. The user interface side of the Ethernet NTU enables service providers to offer critical capabilities such as flexible bandwidth granularity, CoS and VLANs, in effect allowing them to offer SLA guarantees to their customers. Certain applications, such as VoIP and circuit emulation, require prioritization to ensure dependable delivery of real-time traffic, especially in the presence of excess traffic from lower priority sources. The prioritization and associated rate limitation are typically controlled on a per-service and aggregate basis. VLAN tagging and stacking is needed in order to separate traffic sources from different customers, minimize the number of VLANs in the provider’s network, provide VLAN 2 © 2006 RAD Data Communications Ltd.
  5. 5. White Paper: Ethernet OAM tunneling, and to control the Tunnel P-bit (class of service) and ensure that service provider traffic doesn’t interfere with user traffic. Figure 2 below shows how NTUs fit within service provider networks. Customer Premises tomer Premise Customer Premises Customer Premises Eth Eth Service Service Eth Eth Provider Provider Multiservice Multiservice Multiservice Multiservice T1 T1/E1 T1 T1/E1 NTU NTU NTU NTU End-to-end service control, SLA monitoring and diagnostics Figure 2 – End-To-End Service Control, SLA Monitoring And Diagnostics The Importance of OAM In addition to providing a clear demarcation and service/SLA management capabilities, a suite of fault monitoring, diagnostic and control capabilities are required to manage the Ethernet services. These include fault indication and isolation, link monitoring, remote diagnostic and loopback tests, connectivity verification, performance monitoring, fault propagation, inband and out-of-band management and remote software download and configuration. These capabilities have been part of traditional carrier class technologies like TDM and ATM for years and successful carrier class Ethernet service delivery and management depend upon an equivalent set of capabilities. Consider the loopback diagnostic tool, a critical function for both TDM and Ethernet networks. Service providers need the ability to test their circuit all the way to the customer premises for new service provisioning or when troubleshooting the network. A basic feature in TDM networks is the ability to activate a remote CPE CSU loop command from the central office. This places the CSU on the customer premises into a test loop state towards the network. For Ethernet networks, the service provider will need to conduct a similar loopback test with the Ethernet NTU looping back packets it receives from the network per port and per VLAN. © 2006 RAD Data Communications Ltd. 3
  6. 6. White Paper: Ethernet OAM Substantial progress from recent standards activity promises widespread availability and interoperability of Ethernet OAM tools. For instance, the IEEE 802.1ag and ITU Y.1731 standards are close to finalization and RAD as well as some other manufacturers have already incorporated pre-standard implementations into their Ethernet demarcation devices. The Need to Support E1/T1 and E3/T3 Circuits If end user applications only required Ethernet services, a Metro Ethernet connection along with an intelligent Ethernet NTU device might be adequate to satisfy their needs. However, the installed base of TDM equipment and services is very large and continues to grow. Adding TDM support to the E-NTU broadens the customer base by addressing the need for multiservice support to justify the purchase of Ethernet services. In fact, the Metro Ethernet Forum (MEF) has defined TDM support as one of the five basic attributes that define carrier-class Ethernet. In the past years we have seen a decline in residential telephone landlines due to the consumer shift to cellular phones. Paradoxically this trend has actually created an increase in the demand for TDM services for backhauling cellular traffic from between cellular base stations and MSC/BSC aggregation points. The cellular operators’ increased demand for E1/T1 and E3/T3 services is attracting new service providers, namely cable multiservice operators (MSOs), which have advanced Ethernet networks and extensive fiber infrastructure. Circuit emulation enables the cellular operators to backhaul E1/T1 traffic (2G) over Ethernet networks while laying the foundation for 3G with high speed Ethernet. By providing multiservice delivery, the cable MSOs can now offer the cellular operators a choice of facilities to effectively compete with the incumbent LECs. E1/T1 circuits are also extensively used in enterprise voice networks. Traditional PBXs use E1/T1/PRI circuits as the primary connections to service providers as well as for inter-facility voice trunking. Although many organizations are moving to replace these systems with IP PBXs, this transition will take years or decades. In fact, a large percentage of organizations have no current plans to move to VoIP – they are perfectly happy with their existing functional and reliable phone systems. 4 © 2006 RAD Data Communications Ltd.
  7. 7. White Paper: Ethernet OAM Pseudo-Wire/Circuit Emulation Once organizations begin using high bandwidth, low cost Ethernet connections for LAN traffic, they will naturally want to converge most, if not all, of their other types of telecommunications services onto it. But as just discussed, these other “non-Ethernet” services are typically TDM circuits that are not compatible with packet transport. However, this is not the case where a pseudo-wire or circuit emulation technology is used. Consider for example, TDMoIP®, a circuit emulation/pseudo-wire technology pioneered by RAD Data Communications and ratified as an implementation agreement by the MFA forum (MPLS - Frame Relay ATM) and in recommendations by the ITU-T and IETF PWE3 groups. As its name implies, TDMoIP is a technology for transporting TDM circuits such as E1/T1 or E3/T3 across IP or MPLS networks, and recently was expanded to use Ethernet networks in accordance with the MEF 8 Implementation Agreement. TDMoIP is similar to ATM AAL1 in that both technologies are used to emulate circuits over packet switched networks. However, unlike ATM, Ethernet networks provide no inherent timing mechanism. Additionally, packet delay variation (aka jitter), packet delay and packet loss create a hostile environment for transmission of synchronous TDM traffic. TDMoIP features a variety of techniques for overcoming these challenges. In general, the synchronous TDM frame is first segmented and then headers are applied to each segment. The headers provide MAC, IP or MPLS addressing together with VLAN and class of service information. The packets are forwarded across the Ethernet connection. At the other end, the original bit stream is reconstructed by removing the headers, concatenating the segments and regenerating the timing. See Figure 3 below for a detailed depiction of TDMoIP. T1/E1 T1/E1 Frame Ethernet Frames Ethernet Frames Frame ETH / IP / MPLS Network • The synchronous bit stream is segmented • Headers are added to each segment to form the Packet • Packets are forwarded to destination over the PSN network • At destination, the original bit stream is transparently reconstructed Figure 3 - TDMoIP © 2006 RAD Data Communications Ltd. 5
  8. 8. White Paper: Ethernet OAM Among the challenges with pseudo-wire circuit emulation technology, regenerating accurate clock timing and ensuring low latency are among the most difficult. A number of applications – chief among them cellular backhaul – depend on extremely low latency and regenerated clock accuracy measured in parts-per-billion in order to ensure successful operation. The rate limitation and priority functions of an NTU are critical for circuit emulation and VoIP. Circuit emulation requires an “always-on” bandwidth pipe, typically 2/1.5 Mbps per E1/T1. Since commercial Ethernet services over fiber start as low as 5 Mbps, circuit emulation must take priority over all other services and the Ethernet NTU must ensure this happens. Multiservice Ethernet Network Termination Units With Ethernet and TDM being price competitive services, integration of both capabilities into one multiservice NTU contributes to a lower service provisioning cost in several ways. A single multiservice NTU reduces inventory levels, provides for simpler management, reduces the possible points of failure at the customer premises, and ultimately costs less than two discrete NTUs. Customer requirements range from the need to support a few E1/T1 circuits to dozens of E1/T1 or E3/T3 lines. Service providers also require aggregation devices located in their COs or POPs that efficiently interwork with the integrated Ethernet and TDMoIP bit streams coming from multiple customer locations. In addition to handling the switched Ethernet traffic, these devices need to “reassemble” the TDMoIP streams back into E1/T1, E3/T3 or into channelized E3/T3, OC-3 or STM-1 formats and pass them off to existing TDM infrastructures. Service providers require that the capital cost of multiservice NTU be as low as possible. Equally important is the need for minimized OAM costs associated with their access networks. 6 © 2006 RAD Data Communications Ltd.
  9. 9. White Paper: Ethernet OAM Ethernet and TDM Service Delivery to Out-of-Footprint Geographies An example of where multiservice Ethernet NTUs are needed is in the delivery and management of Ethernet along with E1/T1 circuits for out-of-footprint customers. Since Ethernet connections must frequently be leased from a wholesale carrier (regional metro Ethernet service provider), the Primary carrier (IXC or CLEC service provider) needs to add a layer of intelligence to support end-to-end NTU functionality. Since the primary service provider will likely have customers located in a variety of territories, it is important to provide a consistent method of delivering service and supporting OAM functions. A multiservice Ethernet NTU provides these critical capabilities as shown below in Figure 4. End-to-end Service control, SLA monitoring and diagnostics - Monitoring segment Out-of-footprint monitoring segment In-Footprint location NTU n*T1/E1 Co-lo NTU Out-of Footprint location Wholesale NTU Primary 10GE Carrier n*T1/E1 Customer Premi ses Carrier GE CPE NMS Customer data Figure 4 – Multiservice Ethernet NTU © 2006 RAD Data Communications Ltd. 7
  10. 10. White Paper: Ethernet OAM RAD Data Communications Solutions Table 1 – RAD Ethernet and TDM Services Over Packet Access Solutions ETX-102 ETX-202 IPmux-11/14 IPmux-16 Gmux-2000 4/8/12/16 x 196 x E1/T1 E1/T1 TDM ports None None 1/2/4 X T1/ E1 2 x OC-3/STM-1 2 x E3/T3 or 2 x w/ APS link CT3 redundancy 1 or 2 x 1 or 2 x GbE UTP 1 or 2 x 2 x GbE, SFP 100BaseFX ETH Network 1 or 2 x UTP/100FX based Fiber SFP based port Fiber SFP based UTP/100FX Redundant uplink Redundant uplink Redundant uplink Redundant uplink 1-4 x 2x 6x User LAN 1-4 X 10/100/1000Bas 10/100BaseT/100 10/100BaseT/ N/A ports 10/100BaseT e/ GbE Fiber Fx 100FX Rate control Rate control Rate control Rate control Traffic Traffic Traffic Traffic QoS/Rate classification and classification and classification and classification and VLAN tagging Limitation prioritization prioritization prioritization prioritization VLAN tagging and VLAN tagging and VLAN tagging and VLAN tagging and stacking stacking stacking stacking Terminal Terminal Terminal Terminal Terminal Telnet Telnet Telnet Telnet Telnet Web browser RADview/Service RADview/Service Web browser Web browser RADview/Service Center Center RADview Lite RADview Lite Center Management SNMP SNMP SNMP SNMP SNMP Remote s/w Remote s/w Remote s/w Remote s/w Remote s/w download and download and download and download and download and configuration configuration configuration configuration configuration 8 © 2006 RAD Data Communications Ltd.
  11. 11. White Paper: Ethernet OAM Summary With Ethernet services becoming the metropolitan – and ultimately wide area – access technology of choice, coupled with the large installed base of TDM devices, a next generation multiservice Ethernet NTU is clearly needed. This next generation multiservice Ethernet NTU must perform the traditional demarcation and OAM functions, as well as provide support for TDM and analog circuits via pseudo-wire/circuit emulation techniques. This critical pseudo-wire capability must meet strict performance requirements for a variety of applications such as cellular backhaul. © 2006 RAD Data Communications Ltd. 9
  12. 12. www.rad.com Corporate Headquarters U.S. Headquarters RAD Data Communications Ltd. RAD Data Communications Inc. 24 Raoul Wallenberg Street 900 Corporate Drive Tel Aviv 69719, Israel Mahwah, NJ 07430 USA Tel: 972-3-6458181 Tel: (201) 529-1100, Fax: 972-3-6498250 Toll Free: 1-800-444-7234 email: market@rad.com Fax: (201) 529-5777 www.rad.com email: market@radusa.com www.radusa.com The RAD name and logo are registered trademarks of RAD Data Communications Ltd. TDMoIP is a registered trademark of RAD Data Communications Ltd. © 2006 RAD Data Communications. All rights reserved. Subject to change without notice. Innovative Access Solutions Catalog no. 802355 Version 3/2006

×