AAL (ATM adaptation layer): a collection of standard protocols used to adapt to user services. AAL is divided into convergent sublayer (CS) and disassembly sublayer (SCR). There are 4 protocol types of AAL: AAL1, AAL2, AAL3/AAL4 and AAL5 support various AAL service types respectively.
AAL1 (ATM adaptation layer 1): AAL1 provides the user with the ability to transmit data at a constant bit rate and provide timing information and structural information. It can also provide certain error correction and error reporting capabilities when necessary. AAL1 supports Class A services.
AAL2 (ATM adaptation layer 2): AAL2 is used to support variable bit rate connection-oriented services. And transmit service clock information at the same time
AAL3/4 (ATM adapter layer 3/4): AAL3/4 supports both connectionless and connection-oriented links, but is mainly used to transmit SMDS packets on the ATM network.
AAL5 (ATM adapter layer 5): AAL5 supports connection-oriented, VBR services, and is mainly used for transmission standard IP services on ATM network and LANE. AAL5 adopts SEAL technology and is currently the easiest one of the AAL recommendations. AAL5 provides low bandwidth overhead and simpler processing requirements for simplified bandwidth performance and error recovery capabilities.
AARP (AppleTalk Address Resolution Protocol): A protocol in the AppleTalk protocol stack that maps data link addresses into network addresses.
Access list: Saved by the router to prevent packets with a certain IP address from entering/outleting a special interface of the router.
Access server: It is generally placed between PSTN and INTERNET, and connects the asynchronous device to a communication processor on a certain LAN or wide area network through network and terminal simulation software.
Active hub: a multi-port device that amplifies the transmission signals of the LAN.
Address mask: used to describe which part of the address refers to the network or subnet, and which part refers to the bit combination of the host. Sometimes referred to as mask.
Address resolution: usually refers to a method to solve the differences between computer addressing methods. Address resolution usually refers to a method of mapping network layer (layer 3) addresses into data link layer (layer 2) addresses.
Administrative distance: The level of trustworthiness of the routing information source. The higher the value, the lower the level of confidence.
ANSI (National Standards Association): A voluntary organization composed of companies, governments and other members. They negotiate standards-related activities, consider U.S. national standards, and work to improve the United States' position in the International Organization for Standardization. In addition, ANSI has developed international and American standards on communications and networks. ANSI is one of the members of the IEC and ISO.
API (application program interface): that is, function call rules description, it defines an interface with the server.
AppleTalk (the series of communication protocols designed by Apple Computer): Currently there are two stages. The first phase was an earlier version, supporting a single physical network with only one network number and only one region. The second stage is a relatively new version that supports multiple logical networks on a single physical network and allows the network to be distributed in more than one region.
ARP (Address Resolution Protocol): Internet protocol that maps IP addresses to MAC addresses. Defined in RFC826.
ASBR (Autonomous System Boundary Router): ASBR is located between an OSPF autonomous system and a non-OSPF network. ASBRs can run OSPF and another routing protocol (such as RIP). The ASBR must be in the non-stub OSPF zone.
ATM (Asynchronous transmission mode): The international standard for cell relay. In ATM, various service types (such as voice, video, or tree) are transmitted in the form of fixed-length (53 bytes) cells. Fixed-length cells enable processing of cells in hardware, thereby reducing the passing delay. The ATM should be designed to utilize high-speed transmission media such as E3, SONET and T3.
AUI (Connection Unit Interface): IEEE 802.3 interface between MAU and NIC (Network Interface Card). The term AUI can also refer to the rear panel port (to which the AUI cable is connected).
Autonomous system: A collection of networks under the public management of shared public routing policies. Autonomous systems are segmented by region, and an autonomous system must be assigned a unique 16-bit number by LANA.
Backbone cabling: Provides interconnected cables between distribution rooms, between distribution rooms and POPs, and between the same LAN building.
Back off: Forced retransmission delay in conflict.
Bandwidth: The difference between the highest frequency and the lowest frequency that a network signal can achieve. This term is also used to describe the rated throughput capability of a network medium or protocol.
Bandwidth reservation: The process of allocating bandwidth to applications that users and network services. Including assigning priority to different business flows based on business flow importance and latency sensitivity. This maximizes the use of available bandwidth, and if the network is congested, low-priority services are discarded. Sometimes called bandwidth allocation.
BECN (Backward Explicit Crowding Notice): In frames opposite to the transmission direction of a congested path encountered, the bits set by the frame relay network, DTE (receiving frames set with BECN bits) will ask the higher-level protocol to take appropriate traffic control actions.
Bit-oriented protocol: a data link layer communication protocol category that can transmit frames regardless of frame content. Compared to byte-oriented protocols, the bit-oriented protocol provides full duplex operation and is more efficient and reliable.
BPDU (Bridge Protocol Data Unit): is a spanning tree protocol greeting data packet, which is sent at configurable intervals and is used to exchange information between network bridges.
BRI (Basic Rate Interface): The ISDN interface consists of two B channels and one D channel for voice, video and data circuit switching communication.
Bridge: A device that connects and delivers packets between two network segments using the same communication protocol. The bridge runs on the data link layer (layer 2) of the OSI reference model. Generally, the bridge can filter, forward, or spread an input frame (based on the MAC address of the frame).
Broadcast: Data packets delivered to all nodes in the network. The broadcast is determined by the broadcast address.
Broadcast address: A special address reserved for sending information to all sites. Generally, the broadcast address is the MAC destination address of all addresses, and the MAC address is usually set to all 1.
Broadcast domain: A collection of all devices that can receive broadcast frames sent by any device in the collection. Because the router does not forward broadcast frames, the broadcast area generally sets the boundary by the router.
Broadcast storm: It is a nasty network event. When an event occurs, many broadcasts are transmitted on all network segments at the same time. Broadcast storms occupy considerable network bandwidth and generally cause network timeouts.
Buffer: A storage area used to process the transferred data. Buffers can be used in the Internet to back off the difference in processing speed between network devices. Data bursts can exist in buffers until they can be processed by slower devices. Sometimes called a package buffer.
Byte-oriented protocol: A category of data link communication protocols that use a specific character in the user's character set to draw boundaries of frames. Most of these protocols have been replaced by bit-oriented protocols.
Category 1 cabling: The first type of cable is one of the five types of unshielded twisted pair cables described in the EIA/TIA-568B standard. It is used for telephone communications, but is not suitable for transmitting data.
Category 2 cabling: The second type of cable is one of the five types of unshielded twisted pair cables described in the EIA/TIA-568B standard. It can transmit data at rates up to 4Mbps.
Category 3 cabling: The third type of cable is one of the five types of unshielded twisted pair cables described in the EIA/TIA-568B standard. It is used in a 10BaseT network and is able to transmit data at rates up to 10Mbps.
Category 4 cabling: The fourth type of cable is one of the five types of unshielded twisted pair cables described in the EIA/TIA-568B standard. It is used in token ring networks and is able to transmit data at rates up to 16Mbps.
Category 5 cabling: Category 5 cable is one of the five unshielded twisted pair cables described in the EIA/TIA-568B standard. It is used to run CDDI and is able to transfer data at rates up to 100Mbps. CBR (Constant Bit Rate): The QOS level defined by the ATM forum for the ATM network. Constant rate is used for connections that rely on accurate clocks to ensure distortion-free transmission.
CCITT (International Telecommunications and Telephone Advisory Committee): An international organization responsible for the development of communication protocols. Now renamed to the International Telecommunications Union-Telecom Standardization Section.
Channelized E1 (channelized E1 line): The access link running at a rate of 2.048 Mbps after the E1 line is divided into 30 B channels and 1 D channels. It supports DDR, frame relay, and X.25.
CHAP (Challenge Handshake Authentication Protocol): Security features supported on lines encapsulated using end-to-end protocols to prevent unauthorized access. It itself does not prevent unauthorized access, it is only used to identify the terminal. The router or access server can then decide whether the user can access it.
CIDR (Levelless In-Domain Routing): BGP4 supports a routing accumulation technology that allows routers to combine routes into groups in order to reduce the routing information carried by the core router. By using CIDR, several IP networks are like a single large network for networks outside the group.
CIR (Specified Information Rate): The information transmission rate allowed by the frame relay network under normal conditions, which is the rate average over a minimum period of time. CIR is calculated in how many bits per second, and it is a key unit of measurement negotiated by tariff metrics.
Circuit switching: During the call, the sender and the receiver must have a dedicated physical circuit switching system, i.e. circuit switching. It is mainly used in telephone company networks. Circuit switching, as a channel access technology, can be compared with contention and token ring delivery technology; as a switching technology, circuit switching can be compared with message switching and packet switching technology.
Client-server computing: This term is used to describe distributed computing (processing) network systems in which things are divided into two parts: client (front end) and server (back end). These two terms (client and server) can be used in both software programs and in actual computing devices. This is also called distributed computing (processing).
CO (Central Office): It refers to the local telephone company connected to all local loops in a given area, and performs circuit switching of user lines within the central office.
Coaxial cable: A hollow cylindrical conductor wrapped with an internal cable. The two coaxial cables currently used in LANs are: a 50-ohm cable for digital signaling, and a 75-ohm cable for analog signals and high-speed digital signaling.
CODEC (Encoder/Decoder): A device that uses PCM technology to convert analog signals into digital bitstreams and can then convert digital signals back to analog signals.
Collision: In Ethernet, when two nodes transmit data at the same time, frames sent from the two devices will collide, and when they meet on a physical medium, each other's data will be corrupted.
Collision domain: In Ethernet, a conflict domain refers to a network area located in a frame collision that occurs when propagating. Both retransmitters and hubs propagate conflicts; LAN switches, bridges and routers do not propagate conflicts.
Communication server: a communication processor that connects asynchronous devices to a local area network or wide area network through network simulation software. It only executes asynchronous routines of IP and IPX protocols.
Convergence: After the topology of the Internet changes, a group of Internet-connected devices running a specific routing protocol agrees with the speed and ability of the topology to change.
CPE (user station equipment): Termination equipment provided by telephone companies, such as terminals, telephones, and modems. It is installed at the user's location and is connected to the telephone company's network.
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