|
Broadcast Radiation
A broadcast storm or broadcast radiation is the accumulation of broadcast and multicast traffic on a computer network. Extreme amounts of broadcast traffic constitute a "broadcast storm". It can consume sufficient network resources so as to render the network unable to transport normal traffic. A packet that induces such a storm is occasionally nicknamed a Chernobyl packet. Causes Most commonly the cause is a switching loop in the Ethernet network topology (i.e. two or more paths exist between switches). As broadcasts and multicasts are forwarded by switches out of every port, the switch or switches will repeatedly rebroadcast broadcast messages and flood the network. Since the layer-2 header does not support a time to live (TTL) value, if a frame is sent into a looped topology, it can loop forever. In some cases, a broadcast storm can be instigated for the purpose of a denial of service (DOS) using one of the packet amplification attacks, such as the smurf attack or fraggle atta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Broadcasting (networking)
In computer networking, telecommunication and information theory, broadcasting is a method of transferring a message to all recipients simultaneously. Broadcasting can be performed as a high-level operation in a program, for example, broadcasting in Message Passing Interface, or it may be a low-level networking operation, for example broadcasting on Ethernet. All-to-all communication is a computer communication method in which each sender transmits messages to all receivers within a group. In networking this can be accomplished using broadcast or multicast. This is in contrast with the point-to-point method in which each sender communicates with one receiver. Addressing methods There are four principal addressing methods in the Internet Protocol: Overview In computer networking, broadcasting refers to transmitting a packet that will be received by every device on the network. In practice, the scope of the broadcast is limited to a broadcast domain. Broadcasting is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ping (networking Utility)
ping is a computer network administration software utility used to test the reachability of a host on an Internet Protocol (IP) network. It is available for virtually all operating systems that have networking capability, including most embedded network administration software. Ping measures the round-trip time for messages sent from the originating host to a destination computer that are echoed back to the source. The name comes from active sonar terminology that sends a pulse of sound and listens for the echo to detect objects under water. Ping operates by means of Internet Control Message Protocol (ICMP) packets. ''Pinging'' involves sending an ICMP echo request to the target host and waiting for an ICMP echo reply. The program reports errors, packet loss, and a statistical summary of the results, typically including the minimum, maximum, the mean round-trip times, and standard deviation of the mean. The command-line options of the ping utility and its output vary between t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Router (computing)
A router is a networking device that forwards data packets between computer networks. Routers perform the traffic directing functions between networks and on the global Internet. Data sent through a network, such as a web page or email, is in the form of data packets. A packet is typically forwarded from one router to another router through the networks that constitute an internetwork (e.g. the Internet) until it reaches its destination node. A router is connected to two or more data lines from different IP networks. When a data packet comes in on one of the lines, the router reads the network address information in the packet header to determine the ultimate destination. Then, using information in its routing table or routing policy, it directs the packet to the next network on its journey. The most familiar type of IP routers are home and small office routers that simply forward IP packets between the home computers and the Internet. More sophisticated routers, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Network Layer
In the seven-layer OSI model of computer networking, the network layer is layer 3. The network layer is responsible for packet forwarding including routing through intermediate routers. Functions The network layer provides the means of transferring variable-length network packets from a source to a destination host via one or more networks. Within the service layering semantics of the OSI network architecture, the network layer responds to service requests from the transport layer and issues service requests to the data link layer. Functions of the network layer include: ; Connectionless communication : For example, IP is connectionless, in that a data packet can travel from a sender to a recipient without the recipient having to send an acknowledgement. Connection-oriented protocols exist at other, higher layers of the OSI model. ; Host addressing :Every host in the network must have a unique address that determines where it is. This address is normally assigned from a hierar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethernet Automatic Protection System
Ethernet Automatic Protection Switching (EAPS) is used to create a fault tolerant topology by configuring a primary and secondary path for each VLAN. Invented by Extreme Networks and submitted to IETF as RFC3619. The idea is to provide highly available Ethernet switched rings (commonly used in Metro Ethernet) to replace legacy TDM based transport protection fiber rings. Other implementations include Ethernet Protection Switching Ring (EPSR) by Allied Telesis which enhanced EAPS to provide full protected transport of IP Triple Play services (voice, video and internet traffic) for xDSL/FTTx deployments. EAPS/EPSR is the most widely deployed Ethernet protection switching solution deployed with major multi-vendor inter-operability support. The EAPS/EPSR are the basis of the ITU G.8032 Ethernet Protection recommendation. Operation A ring is formed by configuring a Domain. Each domain has a single "master node" and many "transit nodes". Each node will have a primary port and a secon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethernet Ring Protection Switching
Ethernet Ring Protection Switching, or ERPS, is an effort at ITU-T under G.8032 Recommendation to provide sub-50ms protection and recovery switching for Ethernet traffic in a ring topology and at the same time ensuring that there are no loops formed at the Ethernet layer. G.8032v1 supported a single ring topology and G.8032v2 supports multiple rings/ladder topology. Overview ERPS specifies protection switching mechanisms and a protocol for Ethernet layer network (ETH) rings. Ethernet Rings can provide wide-area multipoint connectivity more economically due to their reduced number of links. The mechanisms and protocol defined in this Recommendation achieve highly reliable and stable protection; and never form loops, which would fatally affect network operation and service availability. Each Ethernet Ring Node is connected to adjacent Ethernet Ring Nodes participating in the same Ethernet Ring, using two independent links. A ring link is bounded by two adjacent Ethernet Ring Nodes, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metro Ethernet
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. An Ethernet interface is typically more economical 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 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spanning Tree Protocol
The Spanning Tree Protocol (STP) is a network protocol that builds a loop-free logical topology for Ethernet networks. The basic function of STP is to prevent bridge loops and the broadcast radiation that results from them. Spanning tree also allows a network design to include backup links providing fault tolerance if an active link fails. As the name suggests, STP creates a spanning tree that characterizes the relationship of nodes within a network of connected layer-2 bridges, and disables those links that are not part of the spanning tree, leaving a single active path between any two network nodes. STP is based on an algorithm that was invented by Radia Perlman while she was working for Digital Equipment Corporation. In 2001, the IEEE introduced Rapid Spanning Tree Protocol (RSTP) as 802.1w. RSTP provides significantly faster recovery in response to network changes or failures, introducing new convergence behaviors and bridge port roles to do this. RSTP was designed to be b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Link Aggregation
In computer networking, link aggregation is the combining ( aggregating) of multiple network connections in parallel by any of several methods, in order to increase throughput beyond what a single connection could sustain, to provide redundancy in case one of the links should fail, or both. A link aggregation group (LAG) is the combined collection of physical ports. Other umbrella terms used to describe the concept include trunking, bundling, bonding, channeling or teaming. Implementation may follow vendor-independent standards such as Link Aggregation Control Protocol (LACP) for Ethernet, defined in IEEE 802.1AX or the previous IEEE 802.3ad, but also proprietary protocols. Motivation Link aggregation increases the bandwidth and resilience of Ethernet connections. Bandwidth requirements do not scale linearly. Ethernet bandwidths historically have increased tenfold each generation: 10 megabit/s, 100 Mbit/s, 1000 Mbit/s, 10,000 Mbit/s. If one started to bump in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Switching Loop
A switching loop or bridge loop occurs in computer networks when there is more than one layer 2 path between two endpoints (e.g. multiple connections between two network switches or two ports on the same switch connected to each other). The loop creates broadcast storms as broadcasts and multicasts are forwarded by switches out every port, the switch or switches will repeatedly rebroadcast the broadcast messages flooding the network. Since the layer-2 header does not include a time to live (TTL) field, if a frame is sent into a looped topology, it can loop forever. A physical topology that contains switching or bridge loops is attractive for redundancy reasons, yet a switched network must not have loops. The solution is to allow physical loops, but create a loop-free logical topology using link aggregation, shortest path bridging, spanning tree protocol or TRILL on the network switches. Broadcasts In the case of broadcast packets over a switching loop, the situation may devel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disassociation Broadcast
Dissociation, as a concept that has been developed over time, is a wide array of experiences, ranging from a mild emotional detachment from the immediate surroundings, to a more severe disconnection from physical and emotional experiences. The major characteristic of all dissociative phenomena involves a detachment from reality, rather than a loss of reality as in psychosis. The phenomena are diagnosable under the ''DSM-5'' as a group of disorders as well as a symptom of other disorders through various diagnostic tools. Its cause is believed to be related to neurobiological mechanisms, trauma, anxiety, and psychoactive drugs. Research has further related it to suggestibility and hypnosis, and it is inversely related to mindfulness, which is a potential treatment. History French philosopher and psychologist Pierre Janet (1859–1947) is considered to be the author of the concept of dissociation. Contrary to some conceptions of dissociation, Janet did not believe that dissociati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
