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IP Routing
IP routing is the application of traffic routing methodologies to IP networks. This involves technologies, protocols, structure, administrations, and policies of the worldwide Internet infrastructure. In each IP network node, IP routing involves the determination of a suitable path for a network packet from a source to its destination. The process uses rules, obtained from either static configuration or dynamically with routing protocols, to select specific packet forwarding methods to direct traffic to the next available intermediate network node one ''hop'' closer to the desired final destination. The total path potentially spans multiple computer networks. Networks are separated from each other by specialized hosts, called gateways or routers with specialized software support optimized for routing. IP forwarding algorithms in most routing software determine a route through a shortest path algorithm. In routers, packets arriving at an interface are examined for source and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Routing
Routing is the process of selecting a path for traffic in a Network theory, network or between or across multiple networks. Broadly, routing is performed in many types of networks, including circuit-switched networks, such as the public switched telephone network (PSTN), and computer networks, such as the Internet. In packet switching networks, routing is the higher-level decision making that directs network packets from their source toward their destination through intermediate network nodes by specific packet forwarding mechanisms. Packet forwarding is the transit of network packets from one Network interface controller, network interface to another. Intermediate nodes are typically network hardware devices such as Router (computing), routers, gateway (telecommunications), gateways, Firewall (computing), firewalls, or network switch, switches. General-purpose computers also forward packets and perform routing, although they have no specially optimized hardware for the task. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autonomous System (Internet)
An autonomous system (AS) is a collection of connected Internet protocol address, Internet Protocol (IP) routing prefixes under the control of one or more network operators on behalf of a single administrative entity or domain, that presents a common and clearly defined routing policy to the Internet. Each AS is assigned an autonomous system number (ASN), for use in Border Gateway Protocol (BGP) routing. Autonomous System Numbers are assigned to Regional_Internet_registry#Local_Internet_registry, local Internet registries (LIRs) and end-user organizations by their respective Regional Internet registry, regional Internet registries (RIRs), which in turn receive blocks of ASNs for reassignment from the Internet Assigned Numbers Authority (IANA). The IANA also maintains a registry of ASNs which are reserved for private use (and should therefore not be announced to the global Internet). Originally, the definition required control by a single entity, typically an Internet service provid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Network Interface Card
A network interface controller (NIC, also known as a network interface card, network adapter, LAN adapter and physical network interface) is a computer hardware component that connects a computer to a computer network. Early network interface controllers were commonly implemented on expansion cards that plugged into a computer bus. The low cost and ubiquity of the Ethernet standard means that most newer computers have a network interface built into the motherboard, or is contained into a USB-connected dongle, although network cards remain available. Modern network interface controllers offer advanced features such as interrupt and Direct memory access, DMA interfaces to the host processors, support for multiple receive and transmit queues, partitioning into multiple logical interfaces, and on-controller network traffic processing such as the TCP offload engine. Purpose The network controller implements the electronic circuitry required to communicate using a specific physica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unix-like Operating System
A Unix-like (sometimes referred to as UN*X, *nix or *NIX) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-like application is one that behaves like the corresponding Unix command or shell. Although there are general philosophies for Unix design, there is no technical standard defining the term, and opinions can differ about the degree to which a particular operating system or application is Unix-like. Some well-known examples of Unix-like operating systems include Linux, FreeBSD and OpenBSD. These systems are often used on servers as well as on personal computers and other devices. Many popular applications, such as the Apache web server and the Bash shell, are also designed to be used on Unix-like systems. Definition The Open Group owns the UNIX trademark and administers the Single UNIX Specification, with the "UNIX" name being used as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Network Congestion
Network congestion in data networking and queueing theory is the reduced quality of service that occurs when a network node or link is carrying more data than it can handle. Typical effects include queueing delay, packet loss or the blocking of new connections. A consequence of congestion is that an incremental increase in offered load leads either only to a small increase or even a decrease in network throughput. Network protocols that use aggressive retransmissions to compensate for packet loss due to congestion can increase congestion, even after the initial load has been reduced to a level that would not normally have induced network congestion. Such networks exhibit two stable states under the same level of load. The stable state with low throughput is known as congestive collapse. Networks use congestion control and congestion avoidance techniques to try to avoid collapse. These include: exponential backoff in protocols such as CSMA/CA in 802.11 and the similar CSMA/C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retransmission (data Networks)
Retransmission, essentially identical with automatic repeat request (ARQ), is the resending of packets which have been either damaged or lost. Retransmission is one of the basic mechanisms used by protocols operating over a packet switched computer network to provide reliable communication (such as that provided by a reliable byte stream, for example TCP). Such networks are usually "unreliable", meaning they offer no guarantees that they will not delay, damage, or lose packets, or deliver them out of order. Protocols which provide reliable communication over such networks use a combination of acknowledgments (i.e., an explicit receipt from the destination of the data), retransmission of missing or damaged packets (usually initiated by a time-out), and checksums to provide that reliability. Acknowledgment There are several forms of acknowledgement which can be used alone or together in networking protocols: * Positive Acknowledgement: the receiver explicitly notifies the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Internet Control Message Protocol
The Internet Control Message Protocol (ICMP) is a supporting protocol in the Internet protocol suite. It is used by network devices, including routers, to send error messages and operational information indicating success or failure when communicating with another IP address. For example, an error is indicated when a requested service is not available or that a host or router could not be reached. ICMP differs from transport protocols such as TCP and UDP in that it is not typically used to exchange data between systems, nor is it regularly employed by end-user network applications (with the exception of some diagnostic tools like ping and traceroute). A separate Internet Control Message Protocol (called ICMPv6) is used with IPv6. Technical details ICMP is part of the Internet protocol suite as defined in RFC 792. ICMP messages are typically used for diagnostic or control purposes or generated in response to errors in IP operations (as specified in RFC 1122). ICMP ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Equal-cost Multi-path Routing
Equal-cost multi-path routing (ECMP) is a routing strategy where packet forwarding to a single destination can occur over multiple best paths with equal routing priority. Multi-path routing can be used in conjunction with most routing protocols because it is a per-hop local decision made independently at each router. It can substantially increase bandwidth by load-balancing traffic over multiple paths; however, there may be significant problems in deploying it in practice. History Load balancing by per-packet multipath routing was generally disfavored due to the impact of rapidly changing latency, packet reordering and maximum transmission unit (MTU) differences within a network flow, which could disrupt the operation of many Internet protocols, most notably TCP and path MTU discovery. RFC 2992 analyzed one particular multipath routing strategy involving the assignment of flows through hashing flow-related data in the packet header. This solution is designed to avoid these p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metrics (networking)
Routing metrics are configuration values used by a router to make routing decisions. A ''metric'' is typically one of many fields in a routing table. Router metrics help the router choose the best route among multiple feasible routes to a destination. The route will go in the direction of the gateway with the lowest metric. A router metric is typically based on information such as path length, bandwidth, load, hop count, path cost, delay, maximum transmission unit (MTU), reliability and communications cost. Examples A metric can include: * measuring link utilization (using SNMP) * number of hops ( hop count) * speed of the path * packet loss (router congestion/conditions) * network delay Network delay is a design and performance characteristic of a telecommunications network. It specifies the latency for a bit of data to travel across the network from one communication endpoint to another. It is typically measured in multiple ... * path reliability * path band ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subnet Mask
A subnet, or subnetwork, is a logical subdivision of an IP network. Updated by RFC 6918. The practice of dividing a network into two or more networks is called subnetting. Computers that belong to the same subnet are addressed with an identical group of its most-significant bits of their IP addresses. This results in the logical division of an IP address into two fields: the ''network number'' or ''routing prefix'', and the ''rest field'' or ''host identifier''. The ''rest field'' is an identifier for a specific host or network interface. The ''routing prefix'' may be expressed as the first address of a network, written in Classless Inter-Domain Routing (CIDR) notation, followed by a slash character (''/''), and ending with the bit-length of the prefix. For example, is the prefix of the Internet Protocol version 4 network starting at the given address, having 24 bits allocated for the network prefix, and the remaining 8 bits reserved for host addressing. Addresses in the rang ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IP Address
An Internet Protocol address (IP address) is a numerical label such as that is assigned to a device connected to a computer network that uses the Internet Protocol for communication. IP addresses serve two main functions: network interface identification, and location addressing. Internet Protocol version 4 (IPv4) was the first standalone specification for the IP address, and has been in use since 1983. IPv4 addresses are defined as a 32-bit number, which became too small to provide enough addresses as the internet grew, leading to IPv4 address exhaustion over the 2010s. Its designated successor, IPv6, uses 128 bits for the IP address, giving it a larger address space. Although IPv6 deployment has been ongoing since the mid-2000s, both IPv4 and IPv6 are still used side-by-side . IP addresses are usually displayed in a human-readable notation, but systems may use them in various different computer number formats. CIDR notation can also be used to designate how much ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Datagram
A datagram is a basic transfer unit associated with a packet-switched network. Datagrams are typically structured in header and payload sections. Datagrams provide a connectionless communication service across a packet-switched network. The delivery, arrival time, and order of arrival of datagrams need not be guaranteed by the network. History In the early 1970s, the term ''datagram'' was created by combining the words ''data'' and ''telegram'' by the CCITT rapporteur on packet switching, Halvor Bothner-By. While the word was new, the concept had already a long history. In 1964, Paul Baran described, in a RAND Corporation report, a hypothetical military network having to resist a nuclear attack. Small standardized ''message blocks'', bearing source and destination addresses, were stored and forwarded in computer nodes of a highly redundant meshed computer network. Baran wrote: "The network user who has called up a ''virtual connection'' to an end station and has trans ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
