IP Address Resolution and Routing

• Address Resolution Protocol (ARP) [RFC 1010]
  • ARP request - Broadcast ``who is a.b.c.d?''
  • ARP reply - Target alone fills <IP,Physical>
  • ARP cache arp -a
• Reverse Address Resolution Protocol (RARP, RFC 906)
  • Diskless clients request RARP servers
  • DHCP is dynamic allocation
• Behaviour of Host
  • Destination on my net?
  • If yes, use ARP and deliver directly
  • If no, give to default gateway
• Behaviour of Gateway
  • Am I the destination IP?
  • If not, which interface to forward on?
  • Consult Routing Tables to decide