When a router receives a packet there are 3

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When a router receives a packet, there are 3 possibilities: 1. The host destination is on the router’s network 2. The host destination is not on the router’s network, but the router’s routing table has an entry for where to forward the packet 3. The host destination is not on the network and the router’s routing table does not have an entry for where to forward the packet
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IP IP addresses Obtaining IP addresses CIDR IP Header Functions IPv6 Address Resolution Protocol Address Resolution Protocol ( ARP ) is a protocol used for getting MAC address from IP addresses. This is sometimes called “resolving L3 addresses into L2 addresses” or “resolving network layer addresses into link layer addresses.” This is a Link Layer protocol. For example, the hosts A and B are in an office, connected to each other on the office LAN by Ethernet cables and network switches, with no intervening routers. A wants to send a packet to B. Through other means, A determines B’s IP address. In order to send the message, it also needs to know B’s MAC address. First, A searches its cached ARP table to look up B’s IP address for any existing records of B's MAC address. If the MAC address is found, it sends the IP packet on the link layer to the MAC address. If the cache did not produce a result for B’s MAC address, A sends a broadcast ARP message (MAC destination address FF:FF:FF:FF:FF:FF) requesting an answer from B. B’s response will include its MAC address. B may insert an entry for A into its own ARP table for future use. The response information is cached in A's ARP table and the message can now be sent. If A and B were on different networks, the only clarification would be that the destination would be a boarder router and it’s MAC address would be what was returned above.
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Summary Functions of IP Why different parts of IP addresses Why CIDR Obtaining IP addresses IP version 6
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  • Fall '13
  • Kasper
  • IP address, IP addresses, Header addresses

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