IP addressing Számítógép networkok gyakorlata ÓBUDAI EGYETEM 2011 TAVASZI FÉLÉV 3. LABORGYAKORLAT PRÉM DÁNIEL.

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1 IP addressing Számítógép networkok gyakorlata ÓBUDAI EGYETEM 2011 TAVASZI FÉLÉV 3. LABORGYAKORLAT PRÉM DÁNIEL

2 IP address • Logical addressing • 32 bit integer • IP address can be split into two parts: network and host ID 172.16.254.1 10101100.00010000.11111110.00000001

3 IP address properties • Network ID is the same at each host inone network. Host ID has to be different • Routers use the network ID when forwarding packages. • One host can have multiple interfaces – each interface connects to a different network

4 History of IP classes • Back in the dark ages the first 8 bits were the network ID, the rest was the host id • It was realized soon how smal that number is. • In 1981 the Classful Network achitecture was created. It described 5 classes that were self explanatory from the IP address (A, B, C, D, E ) • Scalability was an issue even using this architecture, so in 1993 ”Classless Inter- Domain Routing” (CIDR) architecture was invented which uses variable length network ID

5 IP address classes Classful Network A class0networkhost B class10networkhost C class110networkhost D class1110multicast E class11110reserved ClassLeading bitsFirst octetNumber of networks Number of hosts A class00 – 1272 7 = 1282 24 = 16.777.216 B class10128 – 1912 14 = 16.3842 16 = 65.536 C class110192 – 2232 21 = 2.097.1522 8 = 256 D class1110224 – 239–– E class11110240 – 255––

6 Private IP ranges • Often it is necessary to connect devices to the network, but not to the internet. RFC 1918 manages the private IP addresses that cannot appear on the internet, but are reserved for private use. • Private IP ranges managed by IANA: • example: - 192.168.1.0/24 (mask: 255.255.255.0 | 256 hosts) - 256 networks - 172.17.0.0/16 (mask: 255.255.0.0 | 65.536 hosts) 256 networks ClassFromToNo. Of hosts 1 x A class10.0.0.010.255.255.2552 24 = 16.777.216 16 x B class172.16.0.0172.31.255.2552 20 = 1.048.576 256 x C class192.168.0.0192.168.255.2552 16 = 65.536

7 Virtual network interface • Sometimes it is necessary for hosts to provide services that have to be used by itself. • Such services are provided through the loopback network. • The loopback device is implemented in software only • Canniot appear on the web • Speciális címe a localhost ami a 127.0.0.1 IP cím. Classfirst network address last network address number of hosts 1 x A class127.0.0.0127.255.255.2552 24 = 16.777.216

8 Network and broadcast addresses • networki cím: IP address full of zeroes – xx.xx.xx.0 • Broadcast cím: IP address full of ones – xx.xx.xx.255

9 Subnet mask • Further subcategorize the network • 32 bit number

10 Subnet mask example • 192.168.0.0/24 [mask: 255.255.255.0] • 192.168.0.0/22 [maszk: 255.255.252.0] • 192.198.0.0/26 [maszk: 255.255.255.192] network idrangeBroadcast addr. Állomások száma 192.168.0.0192.168.0.1 – 192.168.0.254192.168.0.255253 network idrangeBroadcast addr Állomások száma 192.168.0.0192.168.0.1 – 192.168.3.254192.168.3.2551022 network idrangeBroadcast addr Állomások száma 192.168.0.0192.168.0.1 – 192.168.0.62192.168.3.6361

11 Címzési módok • Unicast: Egy az egynek kapcsolat Minden cím egyedi és központilag kiosztott, emiatt egyértelműen azonosítja a címzettet. • Multicast: Egy a többnek kapcsolat Lehetővé teszi az adó számára, hogy az üzenete több címzetthez is eljusson. • Broadcast: Egy mindenkinek kapcsolat A multicast speciális esete, ekkor mindenkinek szól az üzenet, így a network összes eleme beolvassa a csomagot.