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Type–length–value
Within communication protocols, TLV (type-length-value or tag-length-value) is an encoding scheme used for optional informational elements in a certain protocol. A TLV-encoded data stream contains code related to the record type, the record value's length, and finally the value itself. Details The type and length are fixed in size (typically 1–4 bytes), and the value field is of variable size. These fields are used as follows: ;Type: A binary code, often simply alphanumeric, which indicates the kind of field that this part of the message represents; ;Length: The size of the value field (typically in bytes); ;Value: Variable-sized series of bytes which contains data for this part of the message. Some advantages of using a TLV representation data system solution are: * TLV sequences are easily searched using generalized parsing functions; * New message elements which are received at an older node can be safely skipped and the rest of the message can be parsed. This is similar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Packed Encoding Rules
Abstract Syntax Notation One (ASN.1) is a standard interface description language for defining data structures that can be serialized and deserialized in a cross-platform way. It is broadly used in telecommunications and computer networking, and especially in cryptography. Protocol developers define data structures in ASN.1 modules, which are generally a section of a broader standards document written in the ASN.1 language. The advantage is that the ASN.1 description of the data encoding is independent of a particular computer or programming language. Because ASN.1 is both human-readable and machine-readable, an ASN.1 compiler can compile modules into libraries of code, codecs, that decode or encode the data structures. Some ASN.1 compilers can produce code to encode or decode several encodings, e.g. packed, BER or XML. ASN.1 is a joint standard of the International Telecommunication Union Telecommunication Standardization Sector (ITU-T) in ITU-T Study Group 17 and ISO/ IEC, o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
XML Encoding Rules
Abstract Syntax Notation One (ASN.1) is a standard interface description language for defining data structures that can be serialized and deserialized in a cross-platform way. It is broadly used in telecommunications and computer networking, and especially in cryptography. Protocol developers define data structures in ASN.1 modules, which are generally a section of a broader standards document written in the ASN.1 language. The advantage is that the ASN.1 description of the data encoding is independent of a particular computer or programming language. Because ASN.1 is both human-readable and machine-readable, an ASN.1 compiler can compile modules into libraries of code, codecs, that decode or encode the data structures. Some ASN.1 compilers can produce code to encode or decode several encodings, e.g. packed, BER or XML. ASN.1 is a joint standard of the International Telecommunication Union Telecommunication Standardization Sector (ITU-T) in ITU-T Study Group 17 and ISO/ IEC, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distinguished Encoding Rules
X.690 is an ITU-T standard specifying several ASN.1 encoding formats: * Basic Encoding Rules (BER) * Canonical Encoding Rules (CER) * Distinguished Encoding Rules (DER) The Basic Encoding Rules (BER) were the original rules laid out by the ASN.1 standard for encoding data into a binary format. The rules, collectively referred to as a ''transfer syntax'' in ASN.1 parlance, specify the exact octets (8-bit bytes) used to encode data. X.680 defines a syntax for declaring data types, for example: booleans, numbers, strings, and compound structures. Each type definition also includes an identifying number. X.680 defines several ''primitive'' data types, for example: BooleanType, IntegerType, OctetStringType. (ASN.1 also provides for ''constructed'' types built from other types.) Types are associated with a ''class''. For example, the primitive types are part of the ''universal'' class. The three other classes (''application'', ''private'', and ''context-specific'') are essen ... [...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. The Internet Engineering Task Force (IETF) republished IS-IS in , but that RFC was later marked as ''historic'' by because it republished a draft rather than a final version of the (International Organization for Standardization) ISO standard, causing confusion. IS-IS has been 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, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Link Layer Discovery Protocol
The Link Layer Discovery Protocol (LLDP) is a vendor-neutral link layer protocol used by network devices for advertising their identity, capabilities, and neighbors on a local area network based on IEEE 802 technology, principally wired Ethernet. The protocol is formally referred to by the IEEE as ''Station and Media Access Control Connectivity Discovery'' specified in IEEE 802.1AB with additional support in IEEE 802.3 section 6 clause 79. LLDP performs functions similar to several proprietary protocols, such as Cisco Discovery Protocol, Foundry Discovery Protocol, Nortel Discovery Protocol and Link Layer Topology Discovery. Information gathered Information gathered with LLDP can be stored in the device management information base (MIB) and queried with the Simple Network Management Protocol (SNMP) as specified in RFC 2922. The topology of an LLDP-enabled network can be discovered by ''crawling'' the hosts and querying this database. Information that may be retrieved inc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basic Encoding Rules
X.690 is an ITU-T standard specifying several ASN.1 encoding formats: * Basic Encoding Rules (BER) * Canonical Encoding Rules (CER) * Distinguished Encoding Rules (DER) The Basic Encoding Rules (BER) were the original rules laid out by the ASN.1 standard for encoding data into a binary format. The rules, collectively referred to as a ''transfer syntax'' in ASN.1 parlance, specify the exact octets (8-bit bytes) used to encode data. X.680 defines a syntax for declaring data types, for example: booleans, numbers, strings, and compound structures. Each type definition also includes an identifying number. X.680 defines several ''primitive'' data types, for example: BooleanType, IntegerType, OctetStringType. (ASN.1 also provides for ''constructed'' types built from other types.) Types are associated with a ''class''. For example, the primitive types are part of the ''universal'' class. The three other classes (''application'', ''private'', and ''context-specific'') are essent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interchange File Format
Interchange File Format (IFF), is a generic container file format originally introduced by Electronic Arts in 1985 (in cooperation with Commodore) in order to facilitate transfer of data between software produced by different companies. IFF files do not have any standard extension. On many systems that generate IFF files, file extensions are not important (the OS stores file format metadata separately from the file name). An .iff extension is commonly used for ILBM format files, which use the IFF container format. Resource Interchange File Format is a format developed by Microsoft and IBM in 1991 that is based on IFF, except the byte order has been changed to little-endian to match the x86 processor architecture. Apple's AIFF is a big-endian audio file format developed from IFF. The TIFF image file format is unrelated. Structure An IFF file is built up from chunks. Each chunk begins with what the specification calls a "Type ID" (what the Macintosh called an OSType, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Post Office Protocol
In computing, the Post Office Protocol (POP) is an application-layer Internet standard protocol used by e-mail clients to retrieve e-mail from a mail server. POP version 3 (POP3) is the version in common use, and along with IMAP the most common protocols for email retrieval. Purpose The Post Office Protocol provides access via an Internet Protocol (IP) network for a user client application to a mailbox (''maildrop'') maintained on a mail server. The protocol supports download and delete operations for messages. POP3 clients connect, retrieve all messages, store them on the client computer, and finally delete them from the server. This design of POP and its procedures was driven by the need of users having only temporary Internet connections, such as dial-up access, allowing these users to retrieve e-mail when connected, and subsequently to view and manipulate the retrieved messages when offline. POP3 clients also have an option to leave mail on the server after download. By c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypertext Transfer Protocol
The Hypertext Transfer Protocol (HTTP) is an application layer protocol in the Internet protocol suite model for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web, where hypertext documents include hyperlinks to other resources that the user can easily access, for example by a mouse click or by tapping the screen in a web browser. Development of HTTP was initiated by Tim Berners-Lee at CERN in 1989 and summarized in a simple document describing the behavior of a client and a server using the first HTTP protocol version that was named 0.9. That first version of HTTP protocol soon evolved into a more elaborated version that was the first draft toward a far future version 1.0. Development of early HTTP Requests for Comments (RFCs) started a few years later and it was a coordinated effort by the Internet Engineering Task Force (IETF) and the World Wide Web Consortium (W3C), with work later moving to t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
File Transfer Protocol
The File Transfer Protocol (FTP) is a standard communication protocol used for the transfer of computer files from a server to a client on a computer network. FTP is built on a client–server model architecture using separate control and data connections between the client and the server. FTP users may authenticate themselves with a clear-text sign-in protocol, normally in the form of a username and password, but can connect anonymously if the server is configured to allow it. For secure transmission that protects the username and password, and encrypts the content, FTP is often secured with SSL/TLS ( FTPS) or replaced with SSH File Transfer Protocol (SFTP). The first FTP client applications were command-line programs developed before operating systems had graphical user interfaces, and are still shipped with most Windows, Unix, and Linux operating systems. Many dedicated FTP clients and automation utilities have since been developed for desktops, servers, mobile devices, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Simple Mail Transfer Protocol
The Simple Mail Transfer Protocol (SMTP) is an Internet standard communication protocol for electronic mail transmission. Mail servers and other message transfer agents use SMTP to send and receive mail messages. User-level email clients typically use SMTP only for sending messages to a mail server for relaying, and typically submit outgoing email to the mail server on port 587 or 465 per . For retrieving messages, IMAP (which replaced the older POP3) is standard, but proprietary servers also often implement proprietary protocols, e.g., Exchange ActiveSync. SMTP's origins began in 1980, building on concepts implemented on the ARPANET since 1971. It has been updated, modified and extended multiple times. The protocol version in common use today has extensible structure with various extensions for authentication, encryption, binary data transfer, and internationalized email addresses. SMTP servers commonly use the Transmission Control Protocol on port number 25 (for plaintex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Communication Protocols
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 are to co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
