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Bidirectional Forwarding Detection
Bidirectional Forwarding Detection (BFD) is a network protocol that is used to detect faults between two routers or switches connected by a link. It provides low-overhead detection of faults even on physical media that doesn't support failure detection of any kind, such as Ethernet, virtual circuits, tunnels and MPLS label-switched paths. BFD establishes a session between two endpoints over a particular link. If more than one link exists between two systems, multiple BFD sessions may be established to monitor each one of them. The session is established with a three-way handshake, and is torn down the same way. Authentication may be enabled on the session. A choice of simple password, MD5 or SHA1 authentication is available. BFD does not have a discovery mechanism; sessions must be explicitly configured between endpoints. BFD may be used on many different underlying transport mechanisms and layers, and operates independently of all of these. Therefore, it needs to be encapsulat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Network Protocol
A communication protocol is a system of rules that allows two or more entities of a communications system to transmit information via any variation of a physical quantity. The protocol defines the rules, syntax, semantics, and synchronization of communication and possible error recovery methods. Protocols may be implemented by hardware, software, or a combination of both. Communicating systems use well-defined formats for exchanging various messages. Each message has an exact meaning intended to elicit a response from a range of possible responses predetermined for that particular situation. The specified behavior is typically independent of how it is to be implemented. Communication protocols have to be agreed upon by the parties involved. To reach an agreement, a protocol may be developed into a technical standard. A programming language describes the same for computations, so there is a close analogy between protocols and programming languages: ''protocols are to communicat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Internet Protocols
The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suite are the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and the Internet Protocol (IP). Early versions of this networking model were known as the Department of Defense (DoD) model because the research and development were funded by the United States Department of Defense through DARPA. The Internet protocol suite provides End-to-end principle, end-to-end data communication specifying how data should be packetized, addressed, transmitted, routed, and received. This functionality is organized into four abstraction layers, which classify all related protocols according to each protocol's scope of networking. An implementation of the layers for a particular application forms a protocol stack. From lowest to highest, the laye ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IPv6
Internet Protocol version 6 (IPv6) is the most recent version of the Internet Protocol (IP), the communication protocol, communications protocol that provides an identification and location system for computers on networks and routes traffic across the Internet. IPv6 was developed by the Internet Engineering Task Force (IETF) to deal with the long-anticipated problem of IPv4 address exhaustion, and was intended to replace IPv4. In December 1998, IPv6 became a Draft Standard for the IETF, which subsequently ratified it as an Internet Standard on 14 July 2017. Devices on the Internet are assigned a unique IP address for identification and location definition. With the rapid growth of the Internet after commercialization in the 1990s, it became evident that far more addresses would be needed to connect devices than the 4,294,967,296 (232) IPv4 address space had available. By 1998, the IETF had formalized the successor protocol, IPv6 which uses 128-bit addresses, theoretically all ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IPv4
Internet Protocol version 4 (IPv4) is the first version of the Internet Protocol (IP) as a standalone specification. It is one of the core protocols of standards-based internetworking methods in the Internet and other packet-switched networks. IPv4 was the first version deployed for production on SATNET in 1982 and on the ARPANET in January 1983. It is still used to route most Internet traffic today, even with the ongoing deployment of Internet Protocol version 6 (IPv6), its successor. IPv4 uses a 32-bit address space which provides 4,294,967,296 (232) unique addresses, but large blocks are reserved for special networking purposes. Purpose The Internet Protocol ("IP") is the protocol that defines and enables internetworking at the internet layer of the Internet Protocol Suite. It gives the Internet a global-scale logical addressing system which allows the routing of IP Network packet, data packets from a source host to the next router that is one Hop (networking), hop closer t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Keepalive
A keepalive (KA) is a message sent by one device to another to check that the link between the two is operating, or to prevent the link from being broken. Description Once a TCP connection has been established, that connection is defined to be valid until one side closes it. Once the connection has entered the connected state, it will remain connected indefinitely. But, in reality, the connection will not last indefinitely. Many firewall or NAT systems will close a connection if there has been no activity in some time period. The Keep Alive signal can be used to trick intermediate hosts to not close the connection due to inactivity. It is also possible that one host is no longer listening (e.g. application or system crash). In this case, the connection is closed, but no FIN was ever sent. In this case, a KeepAlive packet can be used to interrogate a connection to check if it is still intact. A keepalive signal is often sent at predefined intervals, and plays an important role o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IS-IS
Intermediate System to Intermediate System (IS-IS, also written ISIS) is a routing protocol designed to move information efficiently within a computer network, a group of physically connected computers or similar devices. It accomplishes this by determining the best route for data through a packet switching network. The IS-IS protocol is defined in ISO/IEC 10589:2002 as an international standard within the Open Systems Interconnection (OSI) reference design. In 2005, IS-IS was called "the ''de facto'' standard for large service provider network backbones". Description IS-IS is an interior gateway protocol, designed for use within an administrative domain or network. This is in contrast to exterior gateway protocols, primarily Border Gateway Protocol (BGP), which is used for routing between autonomous systems. IS-IS is a link-state routing protocol, operating by reliably flooding link state information throughout a network of routers. Each IS-IS router independent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Open Shortest Path First
Open Shortest Path First (OSPF) is a routing protocol for Internet Protocol (IP) networks. It uses a link state routing (LSR) algorithm and falls into the group of interior gateway protocols (IGPs), operating within a single Autonomous system (Internet), autonomous system (AS). OSPF gathers link state information from available routers and constructs a topology map of the network. The topology is presented as a routing table to the internet layer for routing packets by their destination IP address. OSPF supports Internet Protocol version 4 (IPv4) and Internet Protocol version 6 (IPv6) networks and is widely used in large enterprise networks. IS-IS, another LSR-based protocol, is more common in large Network service provider, service provider networks. Originally designed in the 1980s, OSPF version 2 is defined in RFC 2328 (1998). The updates for IPv6 are specified as OSPF version 3 in RFC 5340 (2008). OSPF supports the Classless Inter-Domain Routing (CIDR) addressing model. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Three-way Handshake
The Transmission Control Protocol (TCP) is one of the main protocols of the Internet protocol suite. It originated in the initial network implementation in which it complemented the Internet Protocol (IP). Therefore, the entire suite is commonly referred to as TCP/IP. TCP provides reliable, ordered, and error-checked delivery of a stream of octets (bytes) between applications running on hosts communicating via an IP network. Major internet applications such as the World Wide Web, email, remote administration, and file transfer rely on TCP, which is part of the transport layer of the TCP/IP suite. SSL/TLS often runs on top of TCP. TCP is connection-oriented, meaning that sender and receiver firstly need to establish a connection based on agreed parameters; they do this through three-way handshake procedure. The server must be listening (passive open) for connection requests from clients before a connection is established. Three-way handshake (active open), retransmission, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Router (computing)
A router is a computer and networking device that Packet forwarding, forwards data packets between computer networks, including internetworks such as the global Internet. Routers perform the "traffic directing" functions on the Internet. A router is connected to two or more data lines from different IP networks. When a data packet comes in on a line, 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. Data packets are forwarded from one router to another through an internetwork until it reaches its destination Node (networking), node. The most familiar type of Internet Protocol, IP routers are Residential gateway, home and small office routers that forward IP packet (other), IP packets between the home computers and the Internet. More sophisticated routers, such as enterprise routers, conne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MPLS Label-switched Path
Multiprotocol Label Switching (MPLS) is a routing technique in telecommunications networks that directs data from one node to the next based on labels rather than network addresses. Whereas network addresses identify endpoints, the labels identify established paths between endpoints. MPLS can encapsulate packets of various network protocols, hence the ''multiprotocol'' component of the name. MPLS supports a range of access technologies, including T1/ E1, ATM, Frame Relay, and DSL. Role and functioning In an MPLS network, labels are assigned to data packets. Packet-forwarding decisions are made solely on the contents of this label, without the need to examine the packet itself. This allows one to create end-to-end circuits across any type of transport medium, using any protocol. The primary benefit is to eliminate dependence on a particular OSI model data link layer (layer 2) technology, and eliminate the need for multiple layer-2 networks to satisfy different types of traffic. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tunneling Protocol
In computer networks, a tunneling protocol is a communication protocol which allows for the movement of data from one network to another. They can, for example, allow private network communications to be sent across a public network (such as the Internet), or for one network protocol to be carried over an incompatible network, through a process called encapsulation. Because tunneling involves repackaging the traffic data into a different form, perhaps with encryption as standard, it can hide the nature of the traffic that is run through a tunnel. Tunneling protocols work by using the data portion of a packet (the payload) to carry the packets that actually provide the service. Tunneling uses a layered protocol model such as those of the OSI or TCP/IP protocol suite, but usually violates the layering when using the payload to carry a service not normally provided by the network. Typically, the delivery protocol operates at an equal or higher level in the layered model than the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
