64 computer science engineering topic what happens

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Unformatted text preview: y IP is 1.2.3.4 Uh oh … 53 ARP (Address Resolu8on Protocol) •  Node uses to map a local IP address to its Link layer addresses Link layer Source Dest. Source Ethernet Ethernet IP From NIC Dest. IP Payload … From DHCP From ARP 54 27 10/23/13 ARP Protocol Stack •  ARP sits right on top of link layer –  No servers, just asks node with target IP to iden8fy itself –  Uses broadcast to reach all nodes ARP Ethernet 55 ARP Messages Node Target One link 56 28 10/23/13 ARP Messages (2) Node Target REQUEST Broadcast Who has IP 1.2.3.4? REPLY I do at 1:2:3:4:5:6 57 Discovery Protocols •  Help nodes find each other –  There are more of them! •  E.g., zeroconf, Bonjour •  Olen involve broadcast –  Since nodes aren’t introduced –  Very handy glue 58 29 10/23/13 Introduc8on to Computer Networks Packet Fragmenta8on(§5.5.5) Computer Science & Engineering Topic •  How do we connect networks with different maximum packet sizes? –  Need to split up packets, or discover the largest size to use Take that It’s too big! Big packet 60 30 10/23/13 Packet Size Problem •  Different networks have different maximum packet sizes –  Or MTU (Maximum Transmission Unit) –  E.g., Ethernet 1.5K, WiFi 2.3K •  Prefer large packets for efficiency –  But what size is too large? –  Difficult because node does not know complete network path 61 Packet Size Solu8ons •  Fragmenta8on (now) –  Split up large packets in the network if they are to...
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This document was uploaded on 04/04/2014.

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