實驗四 Linux 子網域分割 之設定與觀察 教師: 助教:
2 Outline Traditional IP Allocation Netmask: the Concept Subnetting Realization Proxy-ARP Transparent Router Different Lengths of Netmask How Kernel Works Broadcasting Routing Table Lookup Routing Table Cache Experiment
3 Traditional IP Allocation
4 Netmask: the Concept Used to determine whether two hosts are under the same network Unicast : A → B A → Router → C Broadcast : A → Everyone Router : Longest Prefix Match
5 Subnetting Realization - Proxy-ARP Transparent Router Get the mapping between MAC address and IP address of a host by ARP requests Sharing information with each subnet
6 Subnetting Realization - Different Lengths of Netmask
7 How Kernel Works Three possible scenarios when a packet arrives Routing Table Lookup, Routing Cache, Broadcasting Routing Table Lookup
8 How kernel works Routing Cache Broadcasting Set destination Ethernet address to ff:ff:ff:ff:ff:ff
9 Experiment Proxy-ARP B or C ping A B ping C Open ARP on A B or C ping A again B ping C again Longest Prefix Matching and Routing Cache Modify kernel source code and recompiled Load new kernel C ping B to check /var/log/messages Broadcasting