Network Protocols Dynamic Host Configuration Protocol DHCP TDC375 Autumn 03 04 John Kristoff DePaul University 1 Bootstrapping and auto config Host loads boot image and or config from network Station needs to know its own IP address Station only knows its hardware address Station minimally needs Its IP address The default gateway router Its subnet mask and a DNS server or more would be nice TDC375 Autumn 03 04 John Kristoff DePaul University 1 Older less popular methods Reverse ARP RARP ICMP info mask router queries What is the IP address for MAC xxxx yyyy zzzz What is my IP mask and router BOOTP What is my config and maybe boot loader file TDC375 Autumn 03 04 John Kristoff DePaul University 1 To get configuration remotely Broadcast request no source IP yet use 0 0 0 0 this net this host destination use 255 255 255 255 limited bcast Receive response From a configuration server Sends to our MAC since we don t have a IP yet Routers can intercept forward to remote servers TDC375 Autumn 03 04 John Kristoff DePaul University 1 Typical DHCP startup behavior Client Server DHCP DISCOVER DHCP OFFER DHCP REQUEST DHCP ACK DHCP RELEASE TDC375 Autumn 03 04 John Kristoff DePaul University 1 DHCP packet format TDC375 Autumn 03 04 John Kristoff DePaul University 1
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