ipmacaddresstranslation

ipmacaddresstranslation内容摘要：

rver sends broadcast request for address CS 640 8 Reverse Address Resolution Protocol • RARP is part of the TCP/IP specification • RARP operates much like ARP – A requestor broadcasts is RARP request – Servers respond by sending response directly to requestor – Requestor keeps IP delivered by first responder – Requestor keeps sending requests until it gets an IP • Clearly there is a need for redundant RARP servers for reliability – Timeouts can be used to activate backup RARP servers • Backup servers reply to a RARP request if they don’t hear the RARP response from the primary server after some time CS 640 9 Alternatives to RARP • RARP has shortings – Most are subtle and all deal with fact that RARP operates at physical level • BOOTstrap Protocol (BOOTP) was developed as an alternative to RARP – moves process to work level – Uses UDP/IP packets to carry messages • Hosts are still identified by MAC address – How can UDP running over IP be used by a puter to discover its IP address? • Uses special case IP address – limited broadcast – not forwarded by routers • Forces IP to broadcast on LAN before host IP is known • BOOTP server responds using limited broadcast • Request transmission via random timeout to avoid synchronization CS 640 10 Dynamic Configuration • BOOTP was designed for relatively static environment where each host has a permanent work connection – Net manager creates a BOOTP config file with parameters for each h。