Innetworking, anode (Latin:nodus, 'knot') is either a redistribution point or acommunication endpoint withintelecommunication networks orcomputer networks.
A physical network node is an electronic device that is attached to a network, and is capable of creating, receiving, or transmitting information over acommunication channel.[1] In data communication, a physical network node may either bedata communication equipment (such as amodem,hub,bridge orswitch) ordata terminal equipment (such as a digital telephone handset, a printer or ahost computer).
Apassive distribution point such as adistribution frame orpatch panel is not a node.
In data communication, a physical network node may either bedata communication equipment (DCE) such as amodem,hub,bridge orswitch; ordata terminal equipment (DTE) such as a digital telephone handset, a printer or ahost computer.
If a network is alocal area network (LAN) orwide area network (WAN), every LAN or WAN node that participates on thedata link layer must have anetwork address, typically one for eachnetwork interface controller it possesses. Examples are computers, aDSL modem with Ethernet interface andwireless access point. Equipment, such as anEthernet hub or modem withserial interface, that operates only below the data link layer does not require a network address.[2]
If the network in question is theInternet or anintranet, many physical network nodes are host computers, also known asInternet nodes, identified by anIP address, and all hosts are physical network nodes. However, some data-link-layer devices such as switches, bridges and wireless access points do not have an IP host address (except sometimes for administrative purposes), and are not considered to be Internet nodes or hosts, but are considered physical network nodes and LAN nodes.
In the fixed telephone network, a node may be a public or privatetelephone exchange, aremote concentrator or a computer providing someintelligent network service. In cellular communication, switching points and databases such as thebase station controller,home location register,gateway GPRS Support Node (GGSN) andserving GPRS support node (SGSN) are examples of nodes. Cellular networkbase stations are not considered to be nodes in this context.
Incable television systems (CATV), this term has assumed a broader context and is generally associated with afiber optic node. This can be defined as those homes or businesses within a specific geographic area that are served from a common fiber opticreceiver. A fiber optic node is generally described in terms of the number of "homes passed" that are served by that specific fiber node.
In adistributed system network, the nodes areclients,servers orpeers. A peer may sometimes serve as client, sometimes server. In apeer-to-peer oroverlay network, nodes that actively route data for the other networked devices as well as themselves are calledsupernodes.
Distributed systems may sometimes usevirtual nodes so that the system is not oblivious to the heterogeneity of the nodes. This issue is addressed with special algorithms, likeconsistent hashing, as it is the case inAmazon's Dynamo.[3]
Within a vast computer network, the individual computers on the periphery of the network, those that do not also connect other networks, and those that often connect transiently to one or moreclouds are called end nodes. Typically, within the cloud computing construct, the individual user or customer computer that connects into one well-managed cloud is called an end node. Since these computers are a part of the network yet unmanaged by the cloud's host, they present significant risks to the entire cloud. This is called theend node problem.[4] There are several means to remedy this problem but all require instilling trust in the end node computer.[5]
the basic algorithm is oblivious to the heterogeneity in the performance of nodes. To address these issues, Dynamo uses a variant of consistent hashing: instead of mapping a node to a single point in the circle, each node gets assigned to multiple points in the ring. To this end, Dynamo uses the concept of "virtual nodes". A virtual node looks like a single node in the system, but each node can be responsible for more than one virtual node. Effectively, when a new node is added to the system, it is assigned multiple positions (henceforth, "tokens") in the ring.
