Computer Networks | OUTLINE 1.2 Network Hardware

1.2 Network Hardware

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在计算机网络中，一般从两个维度进行考虑：Transmission Technology, Scale.

Transmission Technology 传播技术

一般来说，Transmission Technology有两个广泛用途：

• broadcast links

• point-to-point links

  On a broadcast network
  (注意！发送方式是广播，但目的地地址有三种方式)

• Packets sent by any machine are received by all the others, each machine checks the address field.

  • If the packet is intended for the receiving machine, that machine processes the packet
  • If the packet is intended for some other machine, it is just ignored.
• Unicasting 单播 (点名道姓 但是网卡不产生中断)
• Broadcasting 广播 (所有其他都听到 所有人都要中断)
• Multicasting (subscribe) 组播 (订阅) (解决广播问题，不用全部中断，只让关心的中断)
• 网卡监督地址 中断

• 现在局域网基本上是这种方式

  Point-to-point Network
  To go from the source to the destination, a packet may visit one or more intermediate（中间的） machines (Often multiple routes are possible, finding good ones is important)

Scale

下面我们根据物理大小的不同来定义不同的系统。

根据空间范围的大小从小到大依次为：PAN(个域网), LAN(局域网), MAN(城域网), WAN(广域网), Internetworks(互联网)
下面就来依次介绍以上processor systems.