IP

IP Prefix:

• IDs the network portion of an IP address

  • ex. 192.24.0.0/22 is prefix, 22 is length

• Shorter prefix = more addresses less networks

IP Classes:

1. Class A: (0-127).h.h.h, up to 2^64 hosts

2. Class B: (128-191).n.h.h, up to 2^16 hosts

3. Class C: (192-223).n.n.h, up to 2^8 hosts

• Net ID is 0-223, Host ID is h.h.h

Subnetting:

• Dividing network into subnet

Network Mask:

• Determines NetID vs HostID

• AND the given IP top and Netmask on the bottom for the Net ID

Longest Prefix Matching:

1. In the routing table, mask subnet to find subnet ID

2. If the bits within the mask match, its a valid path. If not, invalid path

Fragmentation:

• Allows transport layer to ignore network layout and reduce overhead

• Can result in fragment loss

• Must be split into 4 fragments

  • ID field: 16 bits of source addr + dest addr + protocol field value of OG

    • Only fragments of the same packet share ID 

  • Flags: 3 bits 0(Don’t fragment)(More Fragments)

  • Fragment Offset: 13 bits and indicates start position of data in OG packet

IPv4 header fields:

• ID: 16 bits ID combination of source addr & dest addr & protocol field value

IPv6:

• Newer than IPv4

• 128 bit address space, 8 groups of 2 bytes

  • ex. AA82:0000:0000:0000:0023:1A3D:ABCD

• Loading 0s can be eliminated

• : replace groups of 0s, one at a time

Deployment:

• Dual stack: Host/router use IPv4 and IPv6

• IPv4 and IPv6 translator

• Warp IPv6 into IPv4