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【速搜问答】ATM网络是什么

问答 admin 3年前 (2020-07-16) 529次浏览 已收录 0个评论

汉英对照:
Chinese-English Translation:

ATM是Asynchronous Transfer Mode(ATM)异步传输模式的缩写,是实现B-ISDN的业务的核心技术之一,为了多种业务设计的通用的面向连接的传输模式。ATM是以信元为基础的一种分组交换和复用技术。

ATM is the abbreviation of asynchronous transfer mode (ATM). It is one of the core technologies to realize B-ISDN service. It is a general connection oriented transmission mode designed for various services. ATM is a cell-based packet switching and multiplexing technology.

ATM 是 Asynchronous Transfer Mode(ATM)异步传输模式的缩写,是实现 B-ISDN 的业务的核心技术之一。ATM 是以信元为基础的一种分组交换和复用技术。

ATM is the abbreviation of asynchronous transfer mode (ATM). It is one of the core technologies to realize B-ISDN service. ATM is a cell-based packet switching and multiplexing technology.

它是一种为了多种业务设计的通用的面向连接的传输模式。它适用于局域网和广域网,它具有高速数据传输率和支持许多种类型如声音、数据、传真、实时视频、CD 质量音频和图像的通信。

It is a general connection oriented transmission mode designed for multiple services. It is suitable for LAN and WAN. It has high data transmission rate and supports many types of communication such as voice, data, fax, real-time video, CD quality audio and image.

ATM 采用面向连接的传输方式,将数据分割成固定长度的信元,通过虚连接进行交换。ATM 集交换、复用、传输为一体,在复用上采用的是异步时分复用方式,通过信息的首部或标头来区分不同信道。

ATM adopts connection oriented transmission mode, which divides data into fixed length cells and exchanges them through virtual connection. ATM integrates switching, multiplexing and transmission. Asynchronous time division multiplexing is adopted in multiplexing. Different channels are distinguished by the header or header of information.

简介

brief introduction

技术特点

Technical features

ATM 是在 LAN 或 WAN 上传送声音、视频图像和数据的宽带技术。它是一项信元中继技术,数据分组大小固定。你可将信元想象成一种运输设备,能够把数据块从一个设备经过 ATM 交换设备传送到另一个设备。

ATM is a broadband technology for transmitting voice, video image and data over LAN or WAN. It is a cell relay technology with fixed packet size. You can think of a cell as a transport device that can transfer blocks of data from one device through an ATM switching device to another.

所有信元具有同样的大小,不像帧中继及局域网系统数据分组大小不定。使用相同大小的信元可以提供一种方法,预计和保证应用所需要的带宽。如同轿车在繁忙交叉路口必须等待长卡车转弯一样,可变长度的数据分组容易在交换设备处引起通信延迟。

All cells have the same size, unlike frame relay and LAN system, the size of data packet is uncertain. Using cells of the same size can provide a way to predict and guarantee the bandwidth required by the application. Just as a car has to wait for a long truck to turn at a busy intersection, variable length data packets are likely to cause communication delays at switching devices.

ATM 的组成

Composition of ATM

ATM 的连接

ATM connection

ATM 面向连接,它需要在通信双方向建立连接,通信结束后再由信令拆除连接。但它摒弃了电路交换中采用的同步时分复用,改用异步时分复用,收发双方的时钟可以不同,可以更有效地利用带宽。

ATM is connection oriented. It needs to establish a connection in both directions of communication, and then remove the connection by signaling after communication. However, it abandons the synchronous time division multiplexing used in circuit switching, and uses asynchronous time division multiplexing instead. The clock of the sender and receiver can be different and the bandwidth can be used more effectively.

ATM 的传送单元

ATM transport unit

ATM 的传送单元是固定长度 53byte 的 CELL(信元),其中 5B 为信元头,用来承载该信元的控制信息;48B 为信元体,用来承载用户要分发的信息。信头部分包含了选择路由用的 VPI(虚通道标识符)/VCI(虚通路标示符)信息,因而它具有分组交换的特点。

The transmission unit of ATM is a fixed length 53byte cell (cell), in which 5b is the cell head to carry the control information of the cell, and 48b is the cell body to carry the information to be distributed by users. The header contains VPI (virtual channel identifier) / VCI (virtual path identifier) information for routing, so it has the characteristics of packet switching.

它是一种高速分组交换,在协议上它将 OSI 第二层的纠错、流控功能转移到智能终端上完成,降低了网络时延,提高了交换速度。

It is a kind of high-speed packet switching. In terms of protocol, it transfers the functions of error correction and flow control of OSI layer 2 to intelligent terminals, which reduces the network delay and improves the switching speed.

发展优势

Development advantages

ATM 的主要优点是高带宽、有保证的服务质量和可扩展的、能提供所有速度与应用的拓扑结构,服务质量标准确保了一个应用所要求的带宽在该应用的信息请求期间都可供使用,例如,ATM 为实况显示的音频和视频成分提供了性能,从而有足够的带宽进行完整的显示。由于 ATM 技术提供了处理声音、视频和数据的通用网络来降低整个网络成本,全世界的电信公司正朝着 ATM 发展。

The main advantages of ATM are high bandwidth, guaranteed quality of service and scalable topology that can provide all speeds and applications. Quality of service standards ensure that the bandwidth required by an application is available during the information request of the application, for example, ATM It provides performance for audio and video components of live display, so that there is enough bandwidth for complete display. As ATM technology provides a common network for processing voice, video and data to reduce the cost of the whole network, telecom companies around the world are moving towards ATM.

ATM 技术是建立在小的、规模不变的单元上的,它使快速交换成为可能,从而使多种等时的数据能在计算机网络传输中统计复用。统计复用规定了“根据需要定带宽”,电信频道不再被时分复用协议限制在固定的数据率上,实质上,一个应用只使用它所需要的带宽。如果一个应用因为突发数据需要附加的带宽,那么它就能请求附加的带宽,这一在处理高带宽应用上的灵活性在战术环境中具有明显的优势。

ATM technology is based on a small, constant size unit. It makes it possible to switch quickly, so that a variety of isochronous data can be statistically multiplexed in computer network transmission. Statistical multiplexing stipulates that “bandwidth should be determined according to needs”. Telecom channel is no longer limited to fixed data rate by TDM protocol. In essence, an application only uses the bandwidth it needs. If an application needs additional bandwidth because of burst data, it can request additional bandwidth. This flexibility in processing high bandwidth applications has obvious advantages in tactical environment.

ATM 协议能为所有的传输类型提供同构网络,不论是支持传统的电话、娱乐电视,还是支持 LAN、MAN 和 WAN 上的计算机网络传输,应用都使用同一协议。在设计上,ATM 协议能处理等时数据,如视频、音频及计算机之间的其他数据通信。ATM 协议在带宽上被设计成可扩展的,并能支持实时的多媒体应用。标准正好能执行 1 级光学载体(OC-1)(51.84Mbps)到 OC-48(2.488Gbps)的传输率。

ATM protocol can provide isomorphic network for all types of transmission, whether it supports traditional telephone, entertainment TV, or computer network transmission over LAN, man and WAN, the application uses the same protocol. In design, ATM protocol can handle isochronous data, such as video, audio and other data communication between computers. ATM protocol is designed to be scalable in bandwidth and can support real-time multimedia applications. The standard can perform the transfer rate from OC-1 (51.84mbps) to OC-48 (2.488gbps).

应用前景

application prospect

把 ATM 网络技术用作局域网的干线,要考虑到存在的大量传统的 LAN(如以太网),要使它们的基础设施和应用软件的投资不受损害,必须发展 ATM 的 LAN 仿真(LANE)技术。传统的 LAN 技术使用无连接的传输,而 ATM 网络则是面向连接的通信,为了使 ATM 网络技术适用于现有的 LAN 技术,ATM 网络的边界设备必须使 LAN 的网络层协议能够用于面向连接的 ATM 的网络。由 ATM 论坛所制订的 LANE 用户网络接口(LUNI)协议,使 ATM 网络边界设备可以控制供通信用的虚拟连接,并且模仿 LAN 无连接特性。这就是使 ATM 网络技术对 LAN 是透明的,或者说 LAN 掩盖了 ATM 网络的某些特性。 LANE 服务的主要目的是使现有的在 LAN 上的应用程序可以通过多种网络层协议,如 IP、IPX、APPN 和 NetBIOS 等,可以访问 ATM 网络,传统 LAN 上的终端设备,也可以利用 LANE 连接在 ATM 上的设备,如连接在 ATM 网络上的服务器、交换机和路由器等。

When ATM network technology is used as the backbone of local area network, it is necessary to develop LAN simulation (Lane) technology of ATM in consideration of the existence of a large number of traditional LANs (such as Ethernet), so that the investment in infrastructure and application software will not be damaged. Traditional LAN technology uses connectionless transmission, while ATM network is connection oriented communication. In order to make ATM network technology suitable for existing LAN technology, the boundary equipment of ATM network must make LAN network layer protocol be able to be used in connection oriented ATM network. Lane user network interface (LUNI) protocol developed by ATM Forum enables ATM network boundary equipment to control virtual connection of supply and communication credit, and imitates LAN connectionless characteristics. This is to make ATM network technology transparent to LAN, or LAN conceals some characteristics of ATM network. The main purpose of Lane service is to enable the existing LAN applications to access ATM network through a variety of network layer protocols, such as IP, IPX, APPN and NetBIOS, to access the ATM network, the terminal equipment on the traditional LAN, and the equipment connected to ATM by lane, such as servers, switches and routers connected to ATM network.

已有多家著名的网络厂商提供构成 ATM 局域网络干线的设备。除了 ATM 网络接口适配器(接口卡)外,主要有 ATM 网络干线交换机和 ATM/LAN 交换机。以 3COM 公司生产的上述设备为例,ATM 网络干线交换机如 CELLPlex 7000;ATM/LAN 交换机如 LinkSwitch 2700。CELLPlex7000 是有 16 个端口的 ATM 网络干线交换机。这些端口称为直接的 ATM 端口,提供所使用的 ATM 网络接口适配器所提供的通信速率。可以用其中 4 个端口连接供共享的公司级服务器,其余 12 个端口可以各连接一台 LinkSwitch 2700 ATM/LAN 交换机,后者有一个端口供连接 ATM 网络干线交换机用,另外它有 12 个以太网端口,每个以太网端口可以连接一个以太网集线器,每个以太网集线器构成一个共享的 LAN 段,供 8 到 12 台 PC 机共享 10Mb/s 的带宽;或者 ATM/LAN 交换机上的每个以太网端口直接连接一台高档微机工作站,由它独占 10Mb/s 的带宽。

A number of famous network manufacturers have provided equipment to form ATM LAN backbone. In addition to ATM network interface adapter (interface card), there are mainly ATM network trunk switch and ATM / LAN switch. Take the ATM / link 7000 as an example. Cellplex7000 is a 16 port ATM network trunk switch. These ports, called direct ATM ports, provide the rate of communication provided by the ATM network interface adapter used. Four of the ports can be used to connect to the shared company level server, and the remaining 12 ports can be connected to a linkswitch 2700 ATM / LAN switch. The latter has one port for connecting the ATM network trunk switch. In addition, it has 12 Ethernet ports. Each Ethernet port can be connected to an Ethernet hub, and each Ethernet hub constitutes a shared one LAN segment, for 8 to 12 PCS to share 10MB / s bandwidth; or each Ethernet port on ATM / LAN switch is directly connected to a high-end microcomputer workstation, which monopolizes the bandwidth of 10MB / s.

连接在共享 LAN 段上的 PC,可以通过 ATM/LAN 交换机访问配有直接 ATM 接口的高档次(超级)服务器。这种访问不要求 PC 作任何改变,可以通过直接的 ATM 接口高速访问连接在 ATM 网络中的服务器。在整个互连网络中对这类公司级服务器的访问是很频繁的,信息吞吐量大,使用 ATMLAN 作为局域网干线可提高整个企业网的性能。

The PC connected on the shared LAN segment can access the high-grade (super) server with direct ATM interface through ATM / LAN switch. This kind of access does not require any changes of PC. It can access the server connected in ATM network through direct ATM interface. In the whole interconnection network, the access to this kind of company level server is very frequent and the information throughput is large. Using atmlan as the LAN trunk can improve the performance of the whole enterprise network.

LAN 仿真的 ATM 网络干线上桥接 LAN 的链路层,使 ATM 网络像无连接的 LAN 那样工作。LAN 仿真使 LAN 的应用层和网络层都见不到 ATM 网络。应用程序和为共享介质的 LAN 所设计的应用程序接口(API)对话,而由 API 层下面的驱动程序和 ATM 网络交互作用。

The link layer of LAN is bridged on the ATM network trunk of LAN simulation, which makes ATM network work like a connectionless LAN. LAN simulation makes the application layer and network layer of LAN can not see ATM network. The application program communicates with the application program interface (API) designed for the LAN of shared media, while the driver under the API layer interacts with the ATM network.

ATM LAN 的应用是有生命力的,它不但可以作为高层办公大楼的局域网络干线,也适用于长度在数公里范围的园区网。今后在千兆位以太网可供普遍使用时,它也不会成为 ATM LAN 的替代物,这是因为千兆位以太网的数据速率虽高,但是它不适用于多媒体通信。此外,用第 5 类 UTP 构成的千兆位以太网通信距离只限于在 100m 以内,不能用作长距离的局域网络干线。

The application of ATM LAN is vital. It can not only be used as the local area network trunk of high-rise office buildings, but also be applied to the campus network with the length of several kilometers. In the future, when Gigabit Ethernet can be widely used, it will not become a substitute for ATM LAN, because although the data rate of Gigabit Ethernet is high, it is not suitable for multimedia communication. In addition, the communication distance of Gigabit Ethernet composed of type 5 UTP is limited to within 100m, so it can not be used as a long-distance LAN trunk.

ATM 通信网络的应用,无论是在 WAN 和 LAN 干线上的应用,其前景都是诱人的,有着广阔的应用发展前途。在这两方面应用发展的一种趋势,是 WAN 和 LAN 连接的一体化,消除两者之间在传统上存在的屏障。今后,对于一些最为渴求带宽的 PC 通信的应用。通过远程信息传送,使 ATM 直接到达桌面机的技术即可实现。达到这种应用水平,可以说真正实现了超级信息高速公路的境界。

Both LAN and WAN have a bright future in the future. One trend of application development in these two aspects is the integration of Wan and LAN connection to eliminate the traditional barrier between them. In the future, for some of the most bandwidth hungry PC communication applications. Through remote information transmission, ATM can reach the desktop directly. To achieve this level of application, it can be said that the super information superhighway is truly realized.

配置要求

Configuration requirements

通过对 ATM 多业务承载网进行了以上研究以后,可以对 ATM 端局交换机下挂的 F/R 交换机提出如下要求:

After the above research on ATM multi service bearer network, the following requirements can be put forward for the F / R switch attached to the ATM end office switch:

1、物理端口接口功能

1. Physical port interface function

(1)E1 接口(接头型号为 RJ48)

(1) E1 interface (connector model is rj48)

物理特性满足 G.703,帧结构满足 G.704 基本帧结构;E1 帧中继接口支持信道化 E1 和非信道化 E1;信道化 E1 支持 N*64Kbps F/R 端口,N 小于等于 30;非信道化 E1 支持 F/R 端口,支持 G.704 TSO 帧同步方式和非帧同步方式。

Physical characteristics meet G.703, frame structure meets g.704 basic frame structure; E1 frame relay interface supports channelized E1 and non channelized E1; channelized E1 supports n * 64Kbps f / R port, n is less than or equal to 30; non channelized E1 supports f / R port, g.704 Tso frame synchronization mode and non frame synchronization mode.

(2)以太网接口:1×10/100base-T 以太网接口,接口类型为 RJ45。

(2) Ethernet interface: 1 × 10 / 100Base-T Ethernet interface, the interface type is RJ45.

2、业务端口

2. Service port

(1)F/R 业务端口

(1) F / R service port

F/R 业务处理能力参数符合 X.144,X.145;支持 U-NI-DTE(X.36)、UNI-DCE(X.36)和 NNI(X.76)。

The F / R service processing capability parameters are consistent with x.144 and x.145, and support u-ni-dte (x.36), uni-dce (x.36) and NNI (x.76).

F/R 端口支持 LMI 协议,DCE 侧支持 LMI 协议自动识别功能,DTE 侧需指定 LMI 协议,LMI 协议支持 Q.933 Annex.A、X.36、X.76。

The F / R port supports LMI protocol, DCE side supports LMI protocol automatic identification function, DTE side needs to specify LMI protocol, LMI protocol supports q.933 annex. A, x.36, x.76.

F/R 端口拥塞告警管理:F/R 端口只报告端口拥塞告警,考虑到 CPU 处理瓶颈,拥塞管理只对输入队列处理(包括 F/R 和 ATM),所以只检查输入队列深度,根据两级门限判断拥塞和严重拥塞。拥塞时长统计分为两级,轻度拥塞时长和严重拥塞时长。拥塞时长只在一次统计数据报告时间段有效,单位为秒。

F / R port congestion alarm management: F / R port only reports port congestion alarm. Considering CPU processing bottleneck, congestion management only deals with input queue (including F / R and ATM), so it only checks the depth of input queue and judges congestion and severe congestion according to two-level threshold. Congestion duration statistics is divided into two levels: mild congestion duration and severe congestion duration. The congestion duration is only valid in one statistical data reporting period, and the unit is seconds.

F/R 端口统计数据包括:F/R 端口收到和发送的帧数、F/R 端口收到和发送的字节数、F/R 端口收到的帧数中太长和太短的数、F/R 端口收到的帧数中 DLCI 无效的帧数、F/R 端口收到的帧中被丢弃的帧数,指违反业务合同及拥塞管理丢失的帧、F/R 端口轻度拥塞时长,F/R 端口严重拥塞时长。

The statistics data of F / R port include: the number of frames received and sent by F / R port, the number of bytes received and sent by F / R port, the number of too long and too short frames received by F / R port, the number of invalid DLCI frames in the frame received by F / R port, and the number of discarded frames in the frame received by F / R port, which refer to the frames lost in violation of service contract and congestion management, the duration of slight congestion at f / R port, and the number of frames that are discarded in F / R port The length of time that the port is heavily congested.

(2)PPP 业务端口

(2) PPP service port

可承载 IP 业务或桥业务;

It can carry IP service or bridge service;

支持安全认证处理;

Support security authentication processing;

支持 PAP/CHAP,认证协议。二者的不同是:采用 PAP 认证时,用户名和密码在链路上透明传输,而 CHAP 采用双方都能识别的加密算法对用户名和密码进行了加密。

Support PAP / chap, authentication protocol. The difference between them is: when PAP authentication is adopted, the user name and password are transparently transmitted on the link, while chap encrypts the user name and password with encryption algorithm that can be recognized by both parties.

(3)HDLC 业务端口

(3) HDLC service port

HDLC 端口由 E1 端口或 E1 端口中的时隙构成,是一种逻辑端口。通过 HDLC-F/R 的连接,F/R 网络可以透明承载 HDLC 用户业务。

HDLC port is a logical port, which is composed of E1 port or time slot in E1 port. Through hdlc-f / R connection, f / R network can transparently carry HDLC user services.

3、连接特性

3. Connection characteristics

应该支持两种连接类型:F/R-to-F/R 和 F/R-to-HDLC。

Two connection types should be supported: F / r-to-f / R and F / r-to-hdlc.

(1)F/R-to-F/R Connection

(1)F/R-to-F/R Connection

基于 F/R 逻辑端口,实现帧中继交叉连接和统计复用功能。

Based on F / R logic port, frame relay cross connection and statistical multiplexing are realized.

(2)F/R-to-HDLC Connection

(2)F/R-to-HDLC Connection

实现 F/R 连接透明承载 E1 接入业务,并且具有 F/R 交叉连接和统计复用的能力。该类连接一侧对应 E1 HDLC 的几个时隙(信道化)或整个 E1 HDLC 端口(非信道化),另一侧对应 F/R

The F / R connection transparently carries E1 access service, and has the ability of F / R cross connection and statistical multiplexing. One side of the connection corresponds to several slots (channelized) of E1 HDLC or the whole E1 HDLC port (non channelized), and the other side corresponds to f / R


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