TCP/IP 详解 卷1 ch2 链路层

1. the purpose of the link layer in the TCP/IP protocol suite is to send and receive (1) IP datagrams for the IP module, (2) ARP requests and replies for the ARP module, and (3) RARP requests and replies for the RARP module.

 

2. 802.3 和 以太网帧格式不同； CSMA/CD : 带冲突检测的载波侦听多路接入

    802.4 令牌总线

    802.5 令牌环

 

3. MTU for Ethernet is 1500 and for 802.3 is 1492

 

4. path MTU : the smallest MTU of any data link that packets traverse between the two hosts.

 

use netstat command to check the interface and MTU

 

/home/a/j/nomad2:netstat -i Name Mtu Net/Dest Address Ipkts Ierrs Opkts Oerrs Collis Queue lo0 8232 loopback localhost 461928 0 461928 0 0 0 e1000g0 1500 x4100.unix-center.net x4100.unix-center.net 153784274 0 139344579 0 0 0 Name Mtu Net/Dest Address Ipkts Ierrs Opkts Oerrs Collis lo0 8252 localhost localhost 461928 0 461928 0 0 e1000g0 1500 fe80::214:4fff:fe45:f196/10 fe80::214:4fff:fe45:f196 153784274 0 139344581 0 0