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Address Plus Port
The Address plus Port (A+P) within the network layer communications protocol for Internet networking is an experimental approach to the IPv4 address shortage. It is a technique for sharing single IPv4 addresses among several users without using stateful network address translation (NAT) in the carrier network. Normal routing only uses the IPv4 address to identify which host an IP packet is destined for. A+P uses the destination TCP or UDP port in addition to the IP address to extend the range of available host addresses. Each host is assigned a unique range of ports which they set as the source port in outbound packets and which they use to receive inbound traffic. A+P is a stateless alternative to conventional stateful NAT, as the A+P gateway does not need to keep track of every TCP or UDP flow. However, it does require A+P aware software at the end-point, capable of limiting the range of port numbers used for originating connections to its allocated range, either in the end ... [...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] |
Communications Protocol
A communication protocol is a system of rules that allows two or more entities of a communications system to transmit information via any kind of 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 pre-determined 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 ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Internet Protocol
The Internet Protocol (IP) is the network layer communications protocol in the Internet protocol suite for relaying datagrams across network boundaries. Its routing function enables internetworking, and essentially establishes the Internet. IP has the task of delivering packets from the source host to the destination host solely based on the IP addresses in the packet headers. For this purpose, IP defines packet structures that encapsulate the data to be delivered. It also defines addressing methods that are used to label the datagram with source and destination information. IP was the connectionless datagram service in the original Transmission Control Program introduced by Vint Cerf and Bob Kahn in 1974, which was complemented by a connection-oriented service that became the basis for the Transmission Control Protocol (TCP). The Internet protocol suite is therefore often referred to as ''TCP/IP''. The first major version of IP, Internet Protocol Version 4 (IPv4), is the do ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IPv4 Address Exhaustion
IPv4 address exhaustion is the depletion of the pool of unallocated IPv4 addresses. Because the original Internet architecture had fewer than 4.3 billion addresses available, depletion has been anticipated since the late 1980s, when the Internet started experiencing dramatic growth. This depletion is one of the reasons for the development and deployment of its successor protocol, IPv6. IPv4 and IPv6 coexist on the Internet. The IP address space is managed globally by the Internet Assigned Numbers Authority (IANA), and by five regional Internet registries (RIRs) responsible in their designated territories for assignment to end users and local Internet registries, such as Internet service providers. The main market forces that accelerated IPv4 address depletion included the rapidly growing number of Internet users, always-on devices, and mobile devices. The anticipated shortage has been the driving factor in creating and adopting several new technologies, including network addr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transmission Control Protocol
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, and a connection between client and server is established before data can be sent. The server must be listening (passive open) for connection requests from clients before a connection is established. Three-way handshake (active open), retransmission, and error detection adds to reliability but lengthens latency. Applica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
User Datagram Protocol
In computer networking, the User Datagram Protocol (UDP) is one of the core communication protocols of the Internet protocol suite used to send messages (transported as datagrams in packets) to other hosts on an Internet Protocol (IP) network. Within an IP network, UDP does not require prior communication to set up communication channels or data paths. UDP uses a simple connectionless communication model with a minimum of protocol mechanisms. UDP provides checksums for data integrity, and port numbers for addressing different functions at the source and destination of the datagram. It has no handshaking dialogues, and thus exposes the user's program to any unreliability of the underlying network; there is no guarantee of delivery, ordering, or duplicate protection. If error-correction facilities are needed at the network interface level, an application may instead use Transmission Control Protocol (TCP) or Stream Control Transmission Protocol (SCTP) which are designed for this ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stateless Protocol
A stateless protocol is a communication protocol in which the receiver must not retain session state from previous requests. The sender transfers relevant session state to the receiver in such a way that every request can be understood in isolation, that is without reference to session state from previous requests retained by the receiver. In contrast, a stateful protocol is a communication protocol in which the receiver may retain session state from previous requests. In computer networks, examples of stateless protocols include the Internet Protocol (IP), which is the foundation for the Internet, and the Hypertext Transfer Protocol (HTTP), which is the foundation of the World Wide Web. Examples of stateful protocols include the Transmission Control Protocol (TCP) and the File Transfer Protocol (FTP). Stateless protocols improve the properties of visibility, reliability, and scalability. Visibility is improved because a monitoring system does not have to look beyond a single req ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Customer Premises Equipment
In telecommunications, a customer-premises equipment or customer-provided equipment (CPE) is any terminal and associated equipment located at a subscriber's premises and connected with a carrier's telecommunication circuit at the demarcation point ("demarc"). The demarc is a point established in a building or complex to separate customer equipment from the equipment located in either the distribution infrastructure or central office of the communications service provider. CPE generally refers to devices such as telephones, routers, network switches, residential gateways (RG), set-top boxes, fixed mobile convergence products, home networking adapters and Internet access gateways that enable consumers to access providers' communication services and distribute them in a residence or enterprise with a local area network (LAN). A CPE can be an active equipment, as the ones mentioned above, or passive equipment such as analogue telephone adapters (ATA) or xDSL-splitters. This incl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IPv4 Residual Deployment (4rd)
IPv4 Residual Deployment (4rd) is an IPv6 transition mechanism for Internet service providers for deployment of Internet Protocol version 6 (IPv6), while maintaining IPv4 service to customers. The protocol and sample applications are specified in RFC 7600. Features IPv4 Residual Deployment has three main features: *Mesh topology: between two endpoints, IPv4 packets take the same direct routes as IPv6 packets. *Shared IPv4 addresses: to deal with the unavoidable IPv4-address shortage, several customers can be assigned a common IPv4 address, with disjoint TCP/UDP port sets assigned to each (an application of the general A+P model of RFC 6346). *Stateless operation: conversions of IPv4 packets into IPv6 packets at domain entry, and the reverse at domain exit, are stateless (i.e., one where ''no per-customer state'' is needed in domain edge nodes). Compared to other IETF-specified mechanisms having the same main features, i.e., MAP-E (RFC 7597, RFC 7598, RFC 2473) and MAP-T (RFC ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mapping Of Address And Port
Mapping of Address and Port (MAP) is a proposal that combines A+P port address translation with the tunneling of legacy IPv4 protocol packets over an ISP's internal IPv6 network. MAP uses the extra bits available in the IPv6 address to contain the extra port range identifier bits of the A+P addressing pair that cannot be encoded directly into the IPv4 address, thus eliminating the need for "port routing" within the carrier network by leveraging the provider's own IPv6 rollout. In effect, MAP is an (almost) stateless alternative to Carrier-grade NAT and DS-Lite that pushes the IPv4 IP address/port translation function (and therefore the maintenance of NAT state) entirely into the existing customer premises equipment IPv4 NAT implementation, thus avoiding the NAT444 and statefulness problems of carrier-grade NAT. See also * DS-Lite * IPv4 Residual Deployment (4rd) IPv4 Residual Deployment (4rd) is an IPv6 transition mechanism for Internet service providers for deployment of In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
