Internetworking Using Tcp/Ip: Part 2

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Unit 7: Internetworking Using TCP/IP: Part 2


IP uses the Address Resolution Protocol, ARP, to bind a next-hop IP address to an equivalent MAC address. ARP defines the format of messages that computers exchange to resolve an address, the encapsulation, and the rules for handling ARP messages. The NAT mechanism allows a site to have multiple computers using the Internet through a single IP address. The User Datagram Protocol provides end-to-end message transport from an application running on one computer to an application running on another computer (Comer, 2009).

Unit 7: Internetworking Using TCP/IP: Part 2

When a router uses a forwarding table to look up a next-hop address, the result is an IP address. What must happen before the datagram can be sent? The forwarding process requires a translation: forwarding uses IP addresses, and a frame transmitted across a physical network that contains the MAC address of the next hop. The IP software translates the next-hop IP address to an equivalent MAC address (Comer, 2009). Some versions of the traceroute program send ICMP messages and others send UDP messages. Experiment with the version on your computer to determine which it sends. Explain your findings. I used Visual Route 2010 to perform a trace route on my ISP Cox.Net ( I also used Microsoft Windows [Version 6.1.7600] and typed tracert at the command prompt. The programs sent UDP messages. There were no errors, so ICMP did not report any. Visual Route trace started on Jan 15, 2011 8:38:11 PM. The host '' (known as and is reachable in 11 hops. In addition, it responded to HTTP requests on port 80 (it is running server Apache, which responded in 113ms). The TTL value of packets received from it is 243.In general this route offers a good throughput, with hops responding on average within 20ms. The DNS lookup was completed almost instantaneously (less than 2ms - this may be the result of caching).Table 1...
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