Ip Adressing Intro
- 1. Data Networking Year 2 IP Addressing Revisited Colm Bennett
- 2. IP Addressing 32 Bit number, 4 decimal parts, e.g.192.168.1.0 Unique Host Address Subnet Mask Identifies which part of the IP address is the Network Address and which is the Host Address Default Gateway IP Address of the router on the same physical segment
- 3. Network/Host Network ID Same for all hosts on the one physical segment Unique within the overall network Host ID Identifies a particular device within this segment Unique within the segment
- 4. Physical Segment Broadcast domain i.e. The part of the network that will respond to a broadcast packet So repeaters, bridges, switches etc all included as they forward on broadcasts But routers don't so a segment is... All devices out of one port of a router All devices between router All devices have same network ID and a unique Host ID
- 5. Classes Class A First Octet 0-127 Network.Host.Host.Host Class B First Octet 128-191 Network.Network.Host.Host Class C First Octet 192-223 Network.Network.Network.Host D and E are for special uses
- 6. Classes Easy way to remember Each class is half the size of the previous 256 possible values for the first Octet Half these are given to class A 1-127 Half the remaining 128 (64) are given to B 128-191 Half the remaining 64 (32) are given to C 192-223 And again for D and E
- 7. Private Address Spaces Class A 10.0.0.0 Class B 16 Class B's starting from 172.16.0.0 Class C 256 Class C's starting from 192.168.0.0
- 8. Subnet Mask Subnet Mask is 32 bit number that indicates the network and host parts of an IP address 1's indicate the network part, 0's the host part Doesn't have any real meaning in isolation Only makes sense when used with an IP address What are the subnet masks implied in the standard Class A, B & C networks?
- 9. Alternative Notation “Slash” notation puts a number after the IP Address indicating how many bits will be used for the network address Sometimes called the “Prefix” as it indicates the IP address is prefixed with a certain number of network bits So 192.168.5.0 /24 means the first 24 bits are the network part Same as subnet mask of 255.255.255.0
- 10. How Many IDs for each class? Network Ids Simply take the total maximum number of the network part for that Class Exception are two class A's not available – 0 and 127 127 is reserved for Loopback and diagnostics e.g. Class C 192.0.0 .0 - 223.255.255 .255 So max number of network Ids is 32*256*256 2,097,152
- 11. How Many Ids for each class? Host Ids Don't use all 0's or all 1's host Ids All 0's identifies the network All 1's is the network broadcast address So always take 2 off the possible hosts Class C (255.255.255.0) has the last octet for hosts So 256 – 2 = 254 Other Classes?