Metro Ethernet

A metropolitan-area Ethernet system

A metropolitan-area Ethernet, Ethernet MAN, or metro Ethernet network is a metropolitan area network (MAN) that is based on Ethernet standards. It is commonly used to connect subscribers to a larger service network or the Internet. Businesses can also use metropolitan-area Ethernet to connect their own offices to each other.[1]

An Ethernet interface is much cheaper than a synchronous digital hierarchy (SONET/SDH) or plesiochronous digital hierarchy (PDH) interface of the same bandwidth. Another distinct advantage of an Ethernet-based access network is that it can be easily connected to the customer network, due to the prevalent use of Ethernet in corporate and, more recently, residential networks. A typical service provider's network is a collection of switches and routers connected through optical fiber. The topology could be a ring, hub-and-spoke (star), or full or partial mesh. The network will also have a hierarchy: core, distribution (aggregation), and access. The core in most cases is an existing IP/MPLS backbone but may migrate to newer forms of Ethernet transport in the form of 10Gbit/s, 40Gbit/s, or 100Gbit/s speeds or even possibly 400Gbit/s to Terabit Ethernet network in the future.

Ethernet on the MAN can be used as pure Ethernet, Ethernet over SDH, Ethernet over Multiprotocol Label Switching (MPLS), or Ethernet over DWDM. Ethernet-based deployments with no other underlying transport are cheaper but are harder to implement in a resilient and scalable manner, which has limited its use to small scale or experimental deployments. SDH-based deployments are useful when there is an existing SDH infrastructure already in place, its main shortcoming being the loss of flexibility in bandwidth management due to the rigid hierarchy imposed by the SDH network. MPLS-based deployments are costly but highly reliable and scalable and are typically used by large service providers.

Metropolitan area networks[]

Familiar network domains are likely to exist regardless of the transport technology chosen to implement metropolitan area networks: Access, aggregation/distribution, and core.[2]

Much of the functionality of Ethernet MANs such as virtual private lines or virtual private networks is implemented by the use of Ethernet VLAN tags that allow differentiation of each part of the network. Logical differentiation of the physical network helps to identify the rights that the traffic has and to ease the management of hosts' access rights with respect to other users and networks.

MPLS-based Ethernet MANs[]

A Multiprotocol Label Switching (MPLS) metro Ethernet network uses MPLS in the service provider's network. The subscriber will get an Ethernet interface on copper (for example, 100BASE-TX) or fiber (such as 100BASE-FX). The customer's Ethernet packet is transported over MPLS and the service provider network uses Ethernet again as the underlying technology to transport MPLS. So, it is Ethernet over MPLS over Ethernet.

Label Distribution Protocol (LDP) signaling can be used as site to site signaling for the inner label (VC label) and Resource reSerVation Protocol-Traffic Engineering (RSVP-TE) or LDP may be used as Network signaling for the outer label.

One restoration mechanism used in an MPLS based Metro Ethernet Networks is Fast ReRoute (FRR) to achieve sub-50ms convergence of MPLS local protection. For each deployment situation the benefit versus cost of MPLS must be weighed carefully, so if not implemented on a carrier's distribution network there might be more benefit for MPLS the core network. In some situations the cost may not warrant the benefits, particularly if sub 50ms convergence time is already being achieved with pure Ethernet.

A comparison of MPLS-based Metro Ethernet against a pure Ethernet MAN:

Ethernet over wireless[]

Some service providers deployed metro Ethernet networks using fixed wireless technology.[5] These networks commonly are engineered with a majority of the network traffic using a mesh of multi-point and point-to-point microwave links. Carriers have more recently[when?] been referred to as metro wireless[6][7] in many cases. Metro Wireless providers in many cases are able to produce shorter installation times due to less permitting and procedure necessary. Many consumers now[when?] rely on this type of technology to allow Internet access in areas where local telephone companies and cable companies do not or will no longer service due to copper theft or other business reasons. Wireless is also commonly used as a true redundant path to the Internet.[citation needed]

Metro-E carriers[]

In late September 2007 Verizon Business announced metro Ethernet across Asia-Pacific including Australia, Singapore, Japan and Hong Kong using Nortel equipment.[8]

In late January 2009, Windstream announced it would begin offering metro Ethernet service to small and medium business customers.[9]

In May 2011, Comcast announced its own metro Ethernet services to business customers in the United States.[10][11]

See also[]


  1. ^ Ralph Santitoro (2003). "Metro Ethernet Services – A Technical Overview" (PDF). Retrieved 2016-01-09.
  2. ^ EANTC. "Carrier Ethernet Services - The Future" (PDF). EANTC. Retrieved 29 May 2011.
  3. ^ "IEEE 802.1: 802.1ag - Connectivity Fault Management".
  4. ^ "IEEE 802.3ah EFM Standard Ratified - Light Reading".
  5. ^ "Technology News". CNET.
  6. ^ "Solutions - NexxCom Wireless".
  7. ^
  8. ^ "Computerworld Australia - The leading source of technology news, analysis and tools for IT decision makers, managers and professionals". Computerworld.
  9. ^ TeleGeography. "Windstream launches Ethernet Internet Access system for SMEs".
  10. ^ Lawson, Stephen. "Comcast Rolls out Metro Ethernet". Telecom and Cable News. Archived from the original on 23 April 2012. Retrieved 16 May 2011.
  11. ^ "Comcast Business Services Extends Availability of its Metro Ethernet Services through its Solutions Provider Program | Business Wire".

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