Why Metro Ethernet? - Technopediasite

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Tuesday, February 12, 2019

Why Metro Ethernet?

Why Metro Ethernet?: Ethernet has brought about a true telecommunication revolution in the world of local area networks (LANs) services. Due to modern technical advances and daily growth in the telecom sector, the requirements imposed on these networks continue to grow. As terminal equipment of the network system becomes more powerful and applications consume more bandwidth as per independent requirements, they generate significant load requirements. Performance difficulties are being handled nowadays by boosting more speeds from 10 Mbit/s to 10 Gbit/s in LANs.
These day's marketplace, the cost of bandwidth has dropped considerably. Telecom Network operators are now facing the problem that the cost of delivering services is too high and there is no way to reduce these costs using existing technology and network structures. Many users are seeking new, better and improved solutions and approaches to further reduce the cost of maintaining and operating their networks. End users want services to be made available more faster and better they also want more control over the network capacity that they are paying for.
comparisons between traditional and Metro Ethernet networks
Traditional & Metro Ethernet Networks

Carrier Grade Ethernet
Carrier Ethernet is the most demanding technology of choice for most carriers in the metropolitan area. Most of the tier 1 and tier 2 carriers are evaluating the possibility of Carrier Ethernet deployments in the network, and some of them have already embarked on massive deployment. In fact Carrier Ethernet has a CAPEX lower than that of any other carrier technology. It is easy and less expensive than ATM, TDM or IP.

Service provider editing requires no truck roll in the system – the fact that the same physical interface can provide services with variable bandwidth (from 0 to 100/1000 Mbps) in better granularity implies that changes can be made in a service without any extra effort or sending a technician to edit the service profile at the remote customer's site. The emergence of triple-play services generates a need for high amounts of bandwidth, which should be provided with QoS and resilience.

➦Support of all services in the metro area
➦Flexible allocation of the network services like –TV, video, voice, Internet, data traffic
➦Assignment of QoS
➦Bandwidth guaranteed for SLAs
➦Failure safety of SLAs
➦Scalability
➦Subscriber identification
➦End to end monitoring
➦Troubleshooting and debugging.

Carrier Class Ethernet
Carrier-class Ethernet is a complete data-oriented technology of the telecom network that is based on optical fiber transport paths. Optical fiber metro networks are expected to become a very flexible distribution platform and it is capable of providing very large bandwidths similar to Gigabit Ethernet. On the other hand, the Metro networks system provide the fine interface granularity (1 Mbit/s, 2 Mbit/s, 10 Mbit/s) depending on the user profile.

Carrier-class Ethernet is play a important role to close the gap between LANs and WANs. This is providing some competition for the older ATM/SDH and E1 technologies since companies can now purchase more bandwidth at a lower cost with the benefit of a granular price structure. This allows them to select and pay for only the bandwidth they need.

User expectations –Reduction in equipment costs
➦Attractive price-to-performance ratio –High availability
➦Fast and proper troubleshooting in case of problems –End-to-end QoS features
➦Guaranteed required bandwidth with quality parameters –Provision of high-speed ports 10Mbit/s – 10Gbit/s –Fine data speed granularity
➦Scalability based on requirements
➦Fast and better bandwidth expansion when required –Low delay and few packet losses 
–Transparency
➦No modification / adaptation of user packets.

Ethernet : A growing Market Places
These days Ethernet is now the most popular network technology in all over the world. It provide the speeds ranging from 10 Mbit/s to 10 Gbit/s. More and more customers would now like to interconnect with the high-speed LANs via MANs and WANs. Big corporations are looking for a better and easy solutions that will allow them to link their branch offices in a cost-effective manner. Current network layer 3 VPN solutions for the 
subscriber of metro area applications are very costly when it comes to implementing a secure, private network architecture using MAN/WAN infrastructures.

In addition, such type of approaches are not optimal for Ethernet data traffic. The existing backbone network (transport) and access areas network have now been joined by a newcomer: The metro area location. It encompasses metropolitan areas or more populated area and major cities and is oriented towards handling significant changes in the traffic characteristics and overall requirements. The metro area is positioned between the conventional backbone network and access areas network. Various solutions are currently under discussion among the service provider involving combinations of layer 1 and layer 2.

Metro Ethernet demand in growing market place
Metro Ethernet demands in Market place
Managed Ethernet Service
Now we can say that Metro Ethernet is expected to mean the finish of the conventional networks. Whatever is now these days still being transported using separate networks for the users will soon be transported via a common network. Voice (VoIP), data (Internet) and video (TV, video on demand) will all be transported via a single large network and fulfill the all requirement of the users. Due to ongoing advances in Ethernet telecom technology, Ethernet can now be put to use beyond the limits of LANs.

The demand for communications between the different corporate offices and also small offices is being met in a straightforward manner by connecting LANs to the wide area network (WAN) via Ethernet interfaces. in fact Ethernet considerably reduces the interface costs since protocol conversion is not required. The service provider’s transport platform is completely transparent for end users.

Service between the two end points provides a transparent layer 1 transport technology which is used by a layer 2 Ethernet connection. Customer benefits include more cost savings since very less network components are required, as well as usage of switches instead of routers and simpler IT management as soon as Ethernet network technology is deployed at all of the access points.

On the carrier Ethernet end, investments must be handled in a very cost-effective manner. A simple and efficient network transport solution is needed to achieve any cost benefits. It is also necessary to integrate already existing network architectures into the Ethernet service.

Managed Metro Ethernet Service
Metro Network 
Hub and Spoke Technology
Most of the point-to-point connections used in metro LANs network based on the hub and spoke technology. Total connections from the external sites pass via the center. There, the most important services are normally fixed up for the access by all parties. Data traffic is intentionally consolidated in this central area of the network systems.

If several external sites needs to access corporate data at the same time, then bandwidth of the network can become tight. The more external sites that wish to be connected at the same time, it is necessary that the more point-to-point connections that are required. In addition, for a new connection (spoke) systems, the hub and the spoke technology equipment must also be reconfigured for the same. Whenever the hub is unavailable in the system, the entire corporate network will be down.

By the use of Multipoint-to-multipoint connections can be solve such problems. Data exist only once in the network system and did not required to follow a path via the center when intended for users in other external sites. Benefits of Multipoint-to-multipoint connections can be used to transparently connect all of the external sites in a corporation. Data rates are forwarded based on the Ethernet MAC addresses.

Metro Ethernet Hub and Spoke Technology
Metro Ethernet Hub & Spoke
Broadband Ethernet Services
These days any new or old broadband application has its own unique requirements that it makes of the transport network. In future to provide the peer-to-peer applications will require these bandwidths along with guaranteed and proper transmission behavior in order to provide real-time capabilities. It is not a matter whether a video transmission involves broadcast, multicast or unicast packets, each of these communication formats has its own unique physical and protocol-specific requirements that must be fulfilled in order to handle the task at hand as best possible.

According to demands more and more, today’s Ethernet LAN technology is rapidly turning into an extension for carriers. This means that transmissions of the data can function as pure layer 2 applications through a transport network. This type of network mechanisms such as layer 2 VPNs or broadcast applications will then be available as services for end users or subscribers.

Alone the provision of physical Ethernet interfaces is not enough to operate multiservices of the network. Availability of network, redundancy in case of any type of problems and central manageability are required to meet the future demand for triple play services. A common provided Ethernet network services extending from the access area all the way to the core area is needed to meet these objectives.

Metro Ethernet Services in Broadband Network
Metro Ethernet Services
SDH Transport Networks
Before approx 40 year the introduction of the synchronous digital hierarchy (SDH) in the telecom world at the end of the 1980s served as the basis for a uniform world wide transport network that allows efficient,reliable and economical network management by the carriers. Telecom networks can be easily adapted with no problems to meet the growing demand for “bandwidth-hungry” applications for the users.

The SDH network standard is now more or less universal for wide area networks in the telecom. SDH network standard made a sizable contribution to the enormous expansion of global communications over the past decade. Its most important contribution in telecom networks is clearly its ability to facilitate interoperability between solutions from different manufacturers. In the ITU standards, SDH is the part of the synchronous optical fiber network (SONET) hierarchy. A further importance of SDH is the extremely high degree of stability in the network that can be attained in networks that are structured using the standard. SDH or SONET includes, in particular, fast maintenance or restoration after problems occur in the network system. The synchronous transmission network standard is, however, very complex in nature and part of its complexity is due to the fact that it was developed with telecommunication network systems for telephony in mind.

If we look back approx 40 years from today's, we will found that most traffic in long-distance networks (LDN) involved telephony while data traffic was significantly less important. At few points, there was a realization that data traffic of the network would becoming increasingly important, but the extent to which data traffic would prevail was still underestimated.

SDH transport Network with metro Ethernet Network
SDH Network

Ethernet Over Optical Fiber
Telecom Long-haul optical fiber networks system are at the core of the global network. In fact fully dominated by a small group of large transnational and global carriers of the network, long-haul optical fiber networks connect to the MANs network system. Their application is transport, so their primary concern is capacity of the network. In most of the cases these optical fiber networks, which have traditionally been based on the system of Synchronous Optical Network (SONET) or Synchronous Digital Hierarchy (SDH) technology, are experiencing optical fiber exhaust as a result of more bandwidth demand. Dense Wavelength Division Multiplexing (DWDM), an optical fiber technology used to increase bandwidth over existing fiber optic backbones networks.

DWDM technology λ based works by combining and transmitting multiple signals simultaneously at different wavelengths on the same optical fiber link. In effect of DWDM technology, one optical fiber is transformed into multiple virtual optical fibers. So, if telecom operators were to multiplex eight OC -48 signals into one optical fiber, telecom operators would increase the carrying capacity of that optical fiber from 2.5 Gb/s to 20 Gb/s and may be more. Currently, because of DWDM technology, single optical fibers have been able to transmit data at speeds up to 400Gb/s and can fulfill the any type of bandwidth requirements . A important advantage to DWDM technology is that it's protocol -and bit-rate -independent. DWDM technology-based telecom networks can transmit data in IP, ATM, SONET /SDH , and Ethernet also, and professionally handle bit rates between 100 Mb/s and 2.5 Gb/s.

Therefore, DWDM technology-based telecom networks can carry different types of traffic at different speeds over an optical fiber channel. With a capacity greater than WDM technology and smaller than DWDM technology, CWDM allows a modest number of channels, typically eight or less, to be stacked in the 1550 nm region of the optical fiber called the C-Band. To dramatically reduce the more cost of the networks, CWDMs technology use uncooled lasers with a relaxed tolerance of ± 3 nm. Whereas DWDM network systems use perfect channel spacing as close to 0.4 nm, On the other hand CWDM technology uses a spacing of 20 nm.


DWDM
➦Many wavelengths in the visual window 

Channel separations in the DWDM system are: 0.4 nm-0.8 nm (10 Gbit/s at 160, channels)/0.05 nm (2.5 GBit/s at 1024 channels) 
Very high capacities 
Large distances 
Very expensive.
CWDM 
Larger channel separations as in the case of DWDM technology 
Channel separations of 20 nm 
usage in the metro area 
Cheaper lasers as in the case of DWDM

Metro Ethernet Services
Metro Ethernet network represents the future of the fast interconnected world and basically represents nothing more than broadband services access for the masses. Metro Ethernet has already been successfully tested in many countries all over the world and should soon be a global standard. In the interest of achieving this ultimate technology, Metro Ethernet networks uses open standards that anyone can freely access the services. A MAN service is characterized by higher data transmission speeds. The unique scope of Metro networks tends to be greater than is the case with LANs. Optical fiber cables are the preferred transmission medium for the same network. The main aim is to achieve easy interconnectivity with other networks with high transmission data capacities.

One basic requirement for networking is a optical fiber connection to the home or up to the customer end. Active components are installed for conversion from fiber to Ethernet. In the customer home, a optical fiber network based on structured category five cabling is installed which can provide as a basis for multiple network connections. These connections are then used to provide the required services to the customer end. Telephone, TV and Internet services can all be provided through a single access point. With the current state-of-the-technology, right now it is theoretically possible for each and every household or users to have a 10 Gbit/s connection. Using virtual LANs (V-LANs), the different ports of the system are distinguished virtually so as to ensure proper and reliable security for all data.

Metro Ethernet services
Characteristics
➦Ethernet-completely ready customer equipment 

Powerful user network interface provided. 
High-speed Ethernet backbone Ethernet virtual connections 
One or more standardized Ethernet interfaces between CE and Metro Ethernet network.
Metro Ethernet service and network details
Metro Ethernet
Carrier Ethernet Solutions
E-Line sevices
–Point-to-point connections
➦Ethernet private line (EPL) = Port based Service
–One service per port (UNI-Interface)
–No service multiplexing
–Good transmission with SLAs
–Fixed bandwidth (MPLS,FR, ATM) 

Ethernet virtual private line (EVPL) = VLAN based Service
–More as one service per port (UNI-Interface)
–Service multiplexing
–common use of bandwidth
–Use VLAN-Tag to separate the services
E-LAN services
–Multipoint-to-multipoint connections 

Ethernet private LAN (EPLAN) 
Ethernet virtual private LAN (EVPLAN) 
Transparent LAN services (TLS)
Internet access services
–Native Ethernet interfaces 10Mbit/s – 1 Gbit/s
–Flexible bandwidth requirements


Point-to-point connections are relatively easy to set up. For multipoint-to-multipoint connections, however, it is necessary to set up virtual connections beforehand between the different endpoints involved in the communications. Various alternatives are available. VLAN trunks, ATM PVCs and MPLS label switch paths (LSPs) are suitable tools. Using this system, it is possible to transport multiple virtual connections via a single physical link.

Service providers are currently looking for solutions that will enable them to introduce Ethernet-based network technologies in metro networks. Currently, there are two possible ways of doing this. These alternatives are classified as an extension of native Ethernet under the IEEE 802.1 group and an encapsulation technique as the transport technology, similar to MPLS. A point-to-point connection is realized between two UNIs.

This makes it possible to set up a symmetrical data connection. The same amount of data can be transmitted in both directions. An Ethernet EVC is structured like a frame relay or ATM connection except that it has a significantly greater bandwidth. A multipoint EVC connects two or more UNIs. The local subscribers are connected to a multipoint EVC. The subscribers are capable of communicating with one another. Data sent by one UNI can be received by one or more UNIs. The users have the impression of being interconnected via a local area network (LAN).

Metro Ethernet
A Metro Ethernet Network connects geographically separate Enterprise networks across a WAN or backbone network owned by a service provider. Metro Ethernet Provides connectivity service across a Metro area using Ethernet as the core technology enabling broadband applications

Metro Access
➥connects subscribers to the providers network 

Referred to as Last mile/First mile
Metro Aggregation 

collector of access networks for a given region 
Performs switching function 
Connects to a WAN or other service networks ( ISPs)

Metro Ethernet service network details
Metro Ethernet mapping
Metro LAN
Point-to-point connections form the backbone of current LAN-to-LAN interconnections. The commonly used 2 Mbit/s connections no longer meet the current data requirements. By using high-speed xDSL connections along with protocol extensions, greater physical ranges can be achieved. Metro providers can put this to good use since greater distances are typically encountered in the metro area.

Within a single metro area, native Ethernet connections can now be used as point-to-point connections for high-speed LAN-to-LAN interconnection. These connections are implemented primarily via Ethernet switches. In order to ensure sufficient availability even when problems occur, redundancy techniques such as spanning trees, VLAN configurations and broadcast control mechanisms are typically employed. These techniques were developed exclusively for LANs and are now reaching their limits. New techniques conceived with the metro area in mind must now be developed and adapted to the existing structures.

Metro Ethernet LAN details
Metro Ethernet LAN details
1G/10Gigabit Ethernet in Metro Access Network
Expectations made of optical transport networks are very high. Over very large distances, a large percentage of Ethernet traffic is transported via existing SDH/SONET networks. Native Ethernet can also be used in cases where it is feasible. 10 Gigabit Ethernet is ideal for use as a backbone network for metro applications. Due to the large distances that can be covered with these interfaces, point-to-point Ethernet connections can be set up.

Using 10GE, packets can be transported from server to server or PC to server over large distances without any need for protocol conversion or frame translation. In comparison to ATM/SDH, these networks are less complex and cost less. In addition, fewer network components are needed since there is no need to convert the data. 10 Gigabit Ethernet reduces the expense and complexity of the networks compared to ATM/SDH while increasing the bandwidth to 10 Gbit/s.

Since fewer network components are required, the amount of money spent on network components and operations is decreased. The overall network architecture is also simplified.It is possible to interconnect campus networks by setting up VLANs and VPN connections via metro networks.

Ethernet network in Access network
Ethernet in Metro Access
➥Access interface for corporate networks into MANs 
Backbone technology for city carriers 
Application areas –Native Ethernet 
Point-to-point connections
Reduces network complexity 
Central backup structure 
Interconnection of campus networks.

Interconnection of Several Metro Networks
One of the objectives of MPLS is to bring together routing and (considerably faster) switching within a single unified standard. This does have certain advantages. For example, combining routing and switching cuts costs and boosts performance. Together, Ethernet and MPLS form the technological basis for very high scalable bandwidths in the network. Ethernet over MPLS makes the WAN faster, more secure and more cost-effective.

Virtual private LAN service (VPLS) is described in Internet Draft (I-D) draft-l2vpn-vpls-ldp-00.txt (previously known as draft-lasserre-vkompella [lasserre-vkompella]). This service involves a class of VPNs that enables connection of multiple sites in a single bridged domain via an existing provider IP/MPLS network. Using VPLS, providers can set up intra- and intermetro connections based on multipoint Ethernet which are transported using a highly scalable IP/MPLS network. VPLS uses an Ethernet interface to implement the customer access point.

several metro network interconnection
Ethernet interconnection with metro networks

L1 Metro Ethernet Service
These services are not aware of Ethernet addresses, or any other addresses. The provider configures the mapping between switches and ports. As a result any packet input at one Switch/port will be output at the configured Switch/port. It is the customers Ethernet switches which will learn addresses of devices at other locations and direct packets appropriately. This is basically a bridging service.

Depending upon the equipment these services may be protocol independent and can be used for Fiber Channel SAN networks or other non-Ethernet traffic.Transparent Frame in Frame out of service with no MAC address awareness.Network Provider Switches configured to map between the Switches and Ports.Customer switches learns addresses.

Details structure of L1 Metro Ethernet service
Metro Ethernet L1


A Layer 2 Metro Ethernet Service can also support incremental bandwidth. Since this is a Layer 2 service addressing knowledge is required and this is aided by the provider equipment. Instead of just allowing traffic through between predefined ports from one location to another the provider equipment learns of the equipment addresses located at various points and forwards accordingly.

Provider switches are often located at the customer premises and are used to support multiple customers. But this is not a requirement if the provider can support the last mile with fiber.

Metro Ethernet Services often use SONET as the Layer 1 for 10 Gbps Ethernet to achieve longer distances and make use of the already large install base of fiber and SONET equipment. This is transparent to the customer as they are given an Ethernet interface to connect their equipment to.
Detail structure of L2 Metro Ethernet Services
L2 Metro Ethernet Services
Overview of Metro Ethernet
Metro Ethernet provides a more efficient shared access into the WAN, sold as a service to end users in increments of 1 Mbps to Gigabit rates.This means that we can have Ethernet on the LAN, Ethernet on the Access and Ethernet on the WAN Core and never need to convert the Frame size or types. With traditional networks the LAN would be Ethernet, the Access could be DS1 and Frame Relay, the WAN core might be OC12 and ATM. Every step required a conversion at Layer 2.

Also since bandwidth can be sold in increments of 1 Mbps when a customer requires additional bandwidth it is a software configuration change. With the DS1 Access link there would have required changing of equipment to a higher speed card, DS3 for example and maybe even the equipment itself if it does not support other cards.

Users traffic can also be separated and prioritized with the use of Vlans and/or MPLS to provide what ATM may provide at a small fraction of the cost of ATM.

Metro Ethernet Network details with end user
Metro Ethernet End User

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