Skip to content

Network Fundamentals

Network Address

All Binary 0's in the HOST portion of the address 

1
2
3
4
5
    204.0.113.0
11001011 00000000 01110001 00000000

11111111 11111111 11111111 00000000
    255.255.255.0

It should NEVER be assigned to any network card EVER! (that regards you aswell Anders.)

Broadcast Address

All binary 1's in the HOST protion of the address 

1
2
3
4
5
    204.0.113.255
11001011 00000000 01110001 11111111

11111111 11111111 11111111 00000000
    255.255.255.0

Host Address

Anything EXCEPT all binary 0's or 1's. Can only be assigned to a network 

1
2
3
4
5
    204.0.113.10
11001011 00000000 01110001 00001010

11111111 11111111 11111111 00000000
    255.255.255.0

Private and Public Addresses
10.0.0.0 10.255.255.255
172.16.0.0 172.31.255.255
192.168.0.0 192.168.255.255

Classless inter-Domain Router Notation

203.0.113.10/24

1
255.255.255.0

11111111 11111111 11111111 00000000 \ 24 bits /

/24 = Length of network Prefix

Subnet Calculator

bits networks hosts
0 2^0 = 1 -
1 2 -
2 4 2
3 8 6
4 16 14
5 32 30
6 64 62
7 128 126
8 256 254
9 512 510
10 1024 1022
n 2^n n-2

Protip Binary Calculations

Read from left to rigth. * Highest number to the far left * Lowest numer to the far rigth.

Example

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
128 64 32 16 8 4 2 1

11001011 00000000 01110001 00000000
\      /


| 128 | 64  | 32  | 16  | 8   | 4   | 2   | 1   |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 1   | 1   | 0   | 0   | 1   | 0   | 1   | 1   |

128 + 64 + 8 + 2 + 1  = 203

Decimal to Hex

Nooo, binary to hexadecimal conversion.. ! | Decimal | Hex | | ------- | --- | | 1 | 1 | | 2 | 2 | | 3 | 3 | | 4 | 4 | | 5 | 5 | | 6 | 6 | | 7 | 7 | | 8 | 8 | | 9 | 9 | | 10 | A | | 11 | B | | 12 | C | | 13 | D | | 14 | E | | 15 | F |

IPV6

IPv6 Structure

2001:0DB8:0002:008D:0000:0000:00A5:52F5

Eliminate Leding 0's

2001:DB8:2:8D:0:0:A5:52F5

Eliminate 0's with :: (Double Colon)

  • Correct 2001:DB8:2:8D::A5:52F5
  • Wrong 2001:DB8:8D::A5::52F5

IPV6 Address Operation

  • Global Communiciation IPv6 Unicast Address (Global Communication)
  • Local Communication IPv6 Link Local Address (Local Communication)

IPv6 Unicast

  • Unicast Address
    • Global Unicast Address
    • Link Local Address
      • FE80::/10
    • Loopback Address
      • ::1/128
    • Unspecified
      • ::/128
    • Unique Local
      • FC00::/7
    • "private" addressing - no NAT

Multicast Address

  • one to many communication
  • Not implemented globally!

Anycast Address

  • One IPv6 address - many devices
  • Used for loadbalancing

SLAAC

Stateless Address Auto-Configuration.

VLSM

Variable Length Subnet Masking

1
2
3
4
5
    *---------*
   / \       / \
  *   *     *   *
 / \ / \   / \ / \
a  b c d  e  f g  h
How many networks do we need ?

  • a = 25 Hosts
  • b = 100 Hosts
  • c = 75 Hosts
  • d = 200 Hosts
  • e = 150 Hosts
  • f = 300 Hosts
  • g = 125 Hosts
  • h = 200 Hosts
Hosts Bits Network ID (Prefix) Mask
300 9
200 8
200 8
150 8
125 7
100 7
75 7
25 5
2 2
2 2
2 2
2 2
2 2

Ping (Packet Internet Groper)

  • ICMP
    • Protocol ping uses, to get repons back if devices responds or not.
    • Transmit
      • Echo Request
    • Receive
      • Echo Reply