Edge device
Encyclopedia
Edge devices are routers, routing switches, integrated access device
s (IADs), multiplexers, and a variety of metropolitan area network
(MAN) and wide area network
(WAN) access devices that provide entry points into enterprise or service provider core networks. Edge devices also provide connections into carrier and service provider networks.
(QoS) and multi-service functions to manage different types of traffic. Consequently, core networks are often designed with switches that use routing protocols such as Open Shortest Path First
(OSPF) or Multiprotocol Label Switching
(MPLS) for reliability and scalability, allowing edge routers to have redundant links to the core network. Links between core networks are different, for example Border Gateway Protocol
(BGP) routers often used for peering exchanges.
or token ring types of local area network
s (LANs) or xDSL equipment may use an Asynchronous Transfer Mode
(ATM) backbone to other core networks. ATM networks send data in cells and use connection-oriented virtual circuits. An IP network is packet oriented; so if ATM is used as a core, packets must be encapsulated in cells and the destination address must be converted to a virtual circuit identifier. Some new types of optical fibre use a Passive optical network
subscriber loop such as GPON, with the edge device connecting to Ethernet
for backhaul (telecommunications)
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(ISDN), T1 circuits, frame relay
, and ATM. An edge device may provide enhanced services, such as virtual private networking (VPN) support, Voice over IP
, and QoS services.
Integrated access device
An Integrated Access Device is a customer premise device that provides access to wide area networks and the Internet. Specifically, it aggregates multiple channels of information including voice and data across a single shared access link to a carrier or service provider PoP...
s (IADs), multiplexers, and a variety of metropolitan area network
Metropolitan area network
A metropolitan area network is a computer network that usually spans a city or a large campus. A MAN usually interconnects a number of local area networks using a high-capacity backbone technology, such as fiber-optical links, and provides up-link services to wide area networks and the...
(MAN) and wide area network
Wide area network
A wide area network is a telecommunication network that covers a broad area . Business and government entities utilize WANs to relay data among employees, clients, buyers, and suppliers from various geographical locations...
(WAN) access devices that provide entry points into enterprise or service provider core networks. Edge devices also provide connections into carrier and service provider networks.
Function
In general, edge devices are normally routers that provide authenticated access (most commonly PPPoA and PPPoE) to faster, more efficient backbone and core networks. The trend is to make the edge device smart and the core device(s) "dumb and fast", so edge routers often include Quality of ServiceQuality of service
The quality of service refers to several related aspects of telephony and computer networks that allow the transport of traffic with special requirements...
(QoS) and multi-service functions to manage different types of traffic. Consequently, core networks are often designed with switches that use routing protocols such as Open Shortest Path First
Open Shortest Path First
Open Shortest Path First is an adaptive routing protocol for Internet Protocol networks. It uses a link state routing algorithm and falls into the group of interior routing protocols, operating within a single autonomous system . It is defined as OSPF Version 2 in RFC 2328 for IPv4...
(OSPF) or Multiprotocol Label Switching
Multiprotocol Label Switching
Multiprotocol Label Switching is a mechanism in high-performance telecommunications networks that directs data from one network node to the next based on short path labels rather than long network addresses, avoiding complex lookups in a routing table. The labels identify virtual links between...
(MPLS) for reliability and scalability, allowing edge routers to have redundant links to the core network. Links between core networks are different, for example Border Gateway Protocol
Border Gateway Protocol
The Border Gateway Protocol is the protocol backing the core routing decisions on the Internet. It maintains a table of IP networks or 'prefixes' which designate network reachability among autonomous systems . It is described as a path vector protocol...
(BGP) routers often used for peering exchanges.
Translation
Edge devices may translate between one type of network protocol and another. For example, EthernetEthernet
Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....
or token ring types of local area network
Local area network
A local area network is a computer network that interconnects computers in a limited area such as a home, school, computer laboratory, or office building...
s (LANs) or xDSL equipment may use an Asynchronous Transfer Mode
Asynchronous Transfer Mode
Asynchronous Transfer Mode is a standard switching technique designed to unify telecommunication and computer networks. It uses asynchronous time-division multiplexing, and it encodes data into small, fixed-sized cells. This differs from approaches such as the Internet Protocol or Ethernet that...
(ATM) backbone to other core networks. ATM networks send data in cells and use connection-oriented virtual circuits. An IP network is packet oriented; so if ATM is used as a core, packets must be encapsulated in cells and the destination address must be converted to a virtual circuit identifier. Some new types of optical fibre use a Passive optical network
Passive optical network
A passive optical network is a point-to-multipoint, fiber to the premises network architecture in which unpowered optical splitters are used to enable a single optical fiber to serve multiple premises, typically 16-128. A PON consists of an optical line terminal at the service provider's central...
subscriber loop such as GPON, with the edge device connecting to Ethernet
Ethernet
Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....
for backhaul (telecommunications)
Backhaul (telecommunications)
In a hierarchical telecommunications network the backhaul portion of the network comprises the intermediate links between the core network, or backbone, of the network and the small subnetworks at the "edge" of the entire hierarchical network...
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Multiservice units
An edge switch for a WAN may be a multiservice unit, meaning that it supports a wide variety of communication technologies, including Integrated Services Digital NetworkIntegrated Services Digital Network
Integrated Services Digital Network is a set of communications standards for simultaneous digital transmission of voice, video, data, and other network services over the traditional circuits of the public switched telephone network...
(ISDN), T1 circuits, frame relay
Frame relay
Frame Relay is a standardized wide area network technology that specifies the physical and logical link layers of digital telecommunications channels using a packet switching methodology...
, and ATM. An edge device may provide enhanced services, such as virtual private networking (VPN) support, Voice over IP
Voice over IP
Voice over Internet Protocol is a family of technologies, methodologies, communication protocols, and transmission techniques for the delivery of voice communications and multimedia sessions over Internet Protocol networks, such as the Internet...
, and QoS services.