1.以太网2帧的结构
http://cisco.sdut.edu.cn/old/course/IntroNet_en/#5.1.1.4
2.IEEE对mac地址的要求
- All MAC addresses assigned to a NIC or other Ethernet device must use that vendor's assigned OUI as the first 3 bytes.
- All MAC addresses with the same OUI must be assigned a unique value in the last 3 bytes.
- 3.mac地址重复的情况是存在的，可以通过软件的形式给予修改
- 4.交换机的转发方式
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- 5.cut-down转发方式
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- Fast-forward switching - Fast-forward switching offers the lowest level of latency. Fast-forward switching immediately forwards a packet after reading the destination address. Because fast-forward switching starts forwarding before the entire packet has been received, there may be times when packets are relayed with errors. This occurs infrequently, and the destination network adapter discards the faulty packet upon receipt. In fast-forward mode, latency is measured from the first bit received to the first bit transmitted. Fast-forward switching is the typical cut-through method of switching.
- Fragment-free switching - In fragment-free switching, the switch stores the first 64 bytes of the frame before forwarding. Fragment-free switching can be viewed as a compromise between store-and-forward switching and fast-forward switching. The reason fragment-free switching stores only the first 64 bytes of the frame is that most network errors and collisions occur during the first 64 bytes. Fragment-free switching tries to enhance fast-forward switching by performing a small error check on the first 64 bytes of the frame to ensure that a collision has not occurred before forwarding the frame. Fragment-free switching is a compromise between the high latency and high integrity of store-and-forward switching, and the low latency and reduced integrity of fast-forward switching.
- 6.缓存的方式
- 7.arp的功能
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- 1）Resolving IPv4 addresses to MAC addresses
- 2）Maintaining a table of mappings
