This document discusses Metrodata's MetroCONNECT solution for delivering carrier Ethernet services over legacy SDH/PDH and serial infrastructures. The MetroCONNECT family provides Ethernet extension and access demarcation, allowing service providers to offer Ethernet connectivity over a variety of access network transports. Key products include the WCM1100 for point-to-point Ethernet extension, the MC12000 chassis for aggregating connections from multiple sites, and managed Ethernet demarcation devices for network visibility and fault management.

1. Carrier Ethernet Services Delivery
Solution Brief
MetroCONNECT
Ethernet Access Networking
Feb, 2011
Metrodata Ltd Fortune House, TW20 8RY U.K.
Tel: +44 (0)1784 744700 www.metrodata.co.uk E-mail: sales@metrodata.co.uk

2. Carrier Ethernet Services Delivery
Introduction
The importance of Ethernet, as the all-pervasive fixed infrastructure data transport vehicle of the
Corporate 'Local-Area Network' (LAN), is such that it can be regarded as nothing less than a fundamental
utility for IT connectivity. Increasingly, Ethernet is also the network media of choice for Corporate
Telephony deployments, via the growth of Voice over IP (VoIP).
Not surprisingly, Ethernet is now starting to be adopted as a transport for Wide-Area Network (WAN)
connectivity. In fact, Telecoms Service Providers have offered physical Ethernet access for many years,
but most almost exclusively such connections have been delivered via Edge Routers, supplied as the
'Customer Premise Equipment' (CPE) element of a 'Managed IP' network service. Only relatively recently
though has Ethernet been offered as a native transport solution, offering the Corporate user a highly
flexible, scalable bandwidth solution, unfettered by the complexity of IP addressing schema and the
potential performance and limited 'Quality of Service' characteristics of Routed infrastructures.
The increasing demand by customers for direct end-to-end Ethernet WAN connectivity presents an
investment challenge to the Service Provider. Whilst in Metropolitan centres, the deployment of high-
speed, fibre based network, over which Ethernet services at up to 1Gbps or beyond might readily be
supported, this is certainly not the case, even in more economically and technologically advanced
countries, for rural locations. Whilst Telecoms Infrastructure Carriers the world over are investing in
upgrading their legacy SDH/PDH infrastructures to so-called 'Next Generation' packet-based networks,
Service Providers can potentially offer Ethernet Access solutions which make use of existing legacy
infrastructures.
Service Provider
Core Network
Customer Customer
Ethernet Edge Ethernet Edge
Site A Site B
Access via Access via
Fibre Legacy SDH/PDH
Ethernet over Fibre Ethernet over E1
Demarcation Device Demarcation Device
(as an example)
Fig. 1: Ethernet Access Delivery may be via a variety of 'Next-Gen' and/or Legacy infrastructure,
such as PDH (E1) shown here
Ethernet Extension & Access Demarcation
The MetroCONNECT family of Ethernet Service Delivery products enables the Telecoms Service
Provider to offer Ethernet services delivered over a range of Access Network Transport architectures.
MetroCONNECT solutions feature two essential technologies, (i) Switched LAN Extension and (ii)
Managed Ethernet Service Demarcation.
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3. Carrier Ethernet Services Delivery
Switched Ethernet Extension
In its most simplistic form, LAN Extension simply offers a transparent Layer-2 Extension of an Ethernet
network across another transport technology. The MetroCONNECT family offers extension solutions for
Fibre, SDH/PDH and Serial network infrastructures. A simple example, featuring point-to-point Ethernet
extension over a single E1 or T1 service via stand-alone WCM1100 products, is shown in Fig. 2 below:
SDH/PDH
Core / Edge Network
Single E1/T1 (Terrestrial/Wireless) Single E1/T1
Clear-channel or Clear-channel or
Fractional Fractional
Ethernet Ethernet
Metrodata WCM1100
Ethernet over E1/T1
Demarcation Devices Customer
Customer
Site A Site B
Fig. 2: Point-to-Point Ethernet Extension over Clear Channel or Fractional (Nx 64Kbps) E1 or T1
service
In line with other family members of the MetroCONNECT range, the WCM1100 product supports the
following core features:
 Copper and Fibre (SFP) switch ports for 10/100/1000 Ethernet (with 'Jumbo' Frame support)
 Clear-channel and Framed / Fractional services
 VLAN tag-switching (802.1q) & traffic prioritisation (802.1p / IP DSCP)
 Comprehensive SNMP/Telnet Management
 Carrier-Ethernet OAM support ('EFM or Link' OAM' IEEE 802.3ah and 'CFM' IEEE 802.1ag)
 Metrodata 'Zero touch' deployment with 'IP over OAM' proxy (or 'far-end' device management
with no remote IP address setting required)
 GFP/VCAT/LCAS support for interoperability with 3rd party central site aggregation / MSP
platform
 TACACS+ for secure authentication
In general, the stand-alone devices within the MetroCONNECT family are used either by Corporate
customers for ad-hoc point-to-point Ethernet extension applications, or as CPE devices by Ethernet
Service Providers, for whom more application detail will be discussed in a later section.
MetroCONNECT solutions offer more deployment flexibility than for just simple Point-to-Point networks.
As shown in Fig. 3 below, Point-to-Multipoint deployments are also possible. In this example scenario,
WCM1100 and WCM1400 units are shown in combination to provide Ethernet extension from a 'Central'
location to three others. In this example, two further aspects of the MetroCONNECT family are
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4. Carrier Ethernet Services Delivery
highlighted, namely (i) the use of VLAN tag switching to define multiple traffic destinations, and (ii) the use
of Virtual Concatenation (VCAT) and Link Capacity Adjustment Scheme (LCAS) to facilitate the 'bonding'
of two or more SDH/PDH circuits to provide greater Ethernet bandwidth in the connection between any
two sites. As a point of further note, the MetroCONNECT SDH/PDH extension products use the well-
defined standard 'Generic Framing Protocol' (GFP) for Ethernet encapsulation over SDH/PDH circuits,
which facilitates potential inter-operability with other network Aggregation platforms.
Single or Multiple
Ethernet Networks
Metrodata
WCM1400
Up to 4x E1/T1
Customer
Site A
SDH/PDH
Core / Edge Network
(Terrestrial/Wireless)
Dual 'bonded'
Single E1/T1 E1/T1
Single E1/T1 Metrodata
WCM1400
Metrodata
WCM1100 Customer
Customer Site D
Site B
Customer
Site C
Fig. 3: Point-to-Multipoint Ethernet Extension over E1 or T1, also illustrating the use of PDH circuit
'bonding' for increased Ethernet bandwidth connections
Fig. 3 illustrates Ethernet extension between Site A and three further sites, B through D. Using VLAN Tag
switching, the following Ethernet connectivity scenarios can be supported within the context of the basic
connectivity illustrated;
1. The Ethernet network A, B, C, D may be a single 'flat' network domain, within which all broadcast
traffic will propagate to each of the locations.
2. The single network at A may contain multiple pre-defined customer VLANs, which may be used
by the WCM1400 to determine the appropriate destinations for appropriate traffic to be switched
to B, C or D accordingly
3. Multiple separate Ethernet networks may be present at A (the WCM1400 can support up to three
separate local Ethernet connections), for which it may be appropriate that traffic is switched to
locations B, C and D accordingly. The WCM1400 may be set to do this, the Ethernet ingress-
ports being used to define different VLAN groupings with may comprise either a single physical
link, e.g. to Sites B and C above, or a multiple 'bonded' link as for site D above.
A wide range of stand-alone MetroCONNECT family devices are available, each with common Operating
System and feature-set. Full details are available via the Metrodata Ltd. Web Site; www.metrodata.co.uk.
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5. Carrier Ethernet Services Delivery
Managed Ethernet Service Demarcation
In addition to their role as Ethernet Extenders, the MetroCONNECT family products are also manageable
'Ethernet Demarcation Devices'. The Corporate customer or Service Provider has management visibility
both towards the WAN service and LAN connection on either side of the MetroCONNECT device. In
addition to SNMP and Command-Line (Via Telnet) management, all devices in the range support
elements of the Carrier Ethernet 'Operations and Management' (OAM) protocol suite, specifically both the
'Ethernet First Mile' (EFM) or 'Link' OAM protocol defined under IEEE 802.3ah and the 'Connectivity Fault
Management' (CFM) protocol defined under IEEE 802.1ag. In the case of the Service Provider, such
protocols enable the MetroCONNECT products to interoperate with a wider Carrier Ethernet environment
and to enable a degree of pro-activity in fault management.
MC12000 Ethernet Service Delivery Platform
For the Service Provider, wishing to connect a number of remote customer clients across a variety of
technologies from the CO or exchange environment, Metrodata offers the MC12000 chassis solution as a
concentration point for Ethernet Extension / Service Delivery applications.
The MC12000 is a resilient chassis solution offering dual-redundant AC or -48V DC PSU options and
managed connectivity for up to 12 modules for Ethernet connection over a variety of media. Specifically,
the following modules are supported:
 Ethernet over single E1/T1
 Ethernet over up to 4x 'bonded' E1/T1 (or aggregation up to 4x single or bonded E1/T1 groups)
 Ethernet over 8x 'bonded' E1/T1 (or aggregation up to 4x single or bonded E1/T1 groups)
 Ethernet over single E3/DS3
 Ethernet over 2x 'bonded' E3/DS3
 Ethernet over single STM1/OC3 (VC4 or nxVC3)
 Ethernet over Serial, (X.21, V.35, EIA.530, HSSI)
 Ethernet over Fibre (dual connection module)
Fig. 4: MC12000 Ethernet Service
Delivery platform
The MC12000 supports network central Ethernet connection in a number of modes, including;
1. A single 'aggregated' Ethernet connection may be made to the Ethernet port on the Systems
Management card, which can then be distributed to any or all remote Ethernet ports linked via
Extension Modules within the MC12000 chassis. VLAN Tag switching definitions may be applied
to the traffic stream to determine remote port connectivity.
2. Multiple central Ethernet connections may be made to individual modules within the MC12000,
for extension either across the particular link served by the same module, or distributed via
different modules, as determined by VLAN Tag switching definitions.
Network Management connectivity can be effected either via a Serial port on the MC12000 Systems
Management card, or in principle via an Ethernet port on the Systems Management Card itself or any
other module within the chassis.
Ethernet-based Network Management is normally configured such as to be constrained within a single
dedicated Management VLAN, which can be designated to terminate within each Access device if
necessary, in order to avoid propagation of management traffic via user network ports.
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6. Carrier Ethernet Services Delivery
Fig. 5 below illustrates a typical configuration for the MC12000 used for Ethernet Access connectivity
across different media in conjunction with various CPE Demarcation devices.
Metrodata
WCM5100
Ethernet/IP
Packet network
STM1/OC3
SDH/PDH
Core / Edge Network Customer
Fibre
(Terrestrial/Wireless) Site D
Metrodata
FCM9004
Single E1/T1 Multiple 'bonded'
E3/DS3
Customer
Metrodata
Site A WCM3200
Metrodata
WCM1100
Customer
Customer Site C
Site B
Fig. 5: MC12000 used for Ethernet Access concentration over a variety of Network Edge Transports
Setup and Management
It is essential that all elements of a Service Delivery network may be comprehensively managed and the
MetroCONNECT family embraces this principle. One of the key themes for management of the
MetroCONNECT environment is “zero touch” installation for the CPE Demarcation units. Through “zero
touch”, the Demarcation devices are simply physically installed and connected. All configuration functions
are performed from the Provider's Management Station(s).
One element of “zero touch management” is auto-discovery. When a device is installed, it will activate
IEEE802.3ah Link OAM. It will then listen for status requests from the MC12000 Systems Manager.
During this auto-discovery phase, the device type and capabilities are retrieved. Metrodata makes use of
the Organisation-specific Extension capabilities of Link-level OAM to enable a management channel to be
established. Once this channel has been established, the MC12000 Systems Manager acts as an IP
proxy to effectively enable remote device management via TELNET or SNMP.
The use of OAM for the management channel also gives the advantage of traffic isolation, since no
management traffic will be visible to the customer and similarly the customer will have no access to the
management sub-systems.
To further enhance the management offerings, simple password management may be upgraded through
the use of TACACS+, and security enhanced further through SSH based encryption.
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7. Carrier Ethernet Services Delivery
In general, the management of Metrodata products can be considered in two phases, configuration and
monitoring. Configuration is normally achieved through the use of a simple, menu driven user interface
available through TELNET or using a web browser and HTTP services. Once a device is configured, it
then enters the monitoring phase where alarms, events and statistics are gathered using SNMP.
Additionally, the demarcation devices may generate TRAP indications to signal problems to the
Management System.
The MetroConnect MC12000 platform offers extensive performance monitoring facilities as well as in-
service and out-of-service test facilities. Where problems are discovered, OAM level loopback tests may
be used to determine the status of links exhibiting problems. These OAM level loops may operate at an
“in-service” level where they are not traffic affecting, or as “out of service” tests where the traffic flows are
disrupted during tests.
Full details of the MC122000 and indeed of the full MetroCONNECT range can be found at the Metrodata
Web Site, at:
http://www.metrodata.co.uk/products/summaries/ethernet-network-access-and-lan-extension.htm
Within the MetroCONNECT range, Metrodata offers products specifically for use as Copper-Copper or
Copper-Fibre Carrier Ethernet Demarcation devices, including advanced capabilities for Performance
Assurance and SLA verification, increasingly required of Ethernet Service Providers by their customers.
This topic is examined in detail in our White Paper, "Managing Ethernet Service Delivery", and full
product details can be found at the Web Site here;
http://www.metrodata.co.uk/solutions/ethernet-extension/carrier-ethernet-demarcation-devices.htm
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