1. 1© 2004, Cisco Systems, Inc. All rights reserved.
IP ADDRESSING AND SUBNETTING

2. 222© 2004, Cisco Systems, Inc. All rights reserved.
• Dada una dirección IP y una mascara de subred, cuantas
subredes hay? y cuantos host hay por cada subred?
• Dada una dirección IP y una mascara de subred, cual es el
numero de Subred?
• Dada una dirección IP y una mascara de subred, cual es la
dirección de broadcast de la Subred?
• Dada una dirección IP y una mascara de subred, cual es el
rango de direcciones IP válidas?
Tipo de Preguntas Subneteo

3. 333© 2004, Cisco Systems, Inc. All rights reserved.
IP Address Review

4. 444© 2004, Cisco Systems, Inc. All rights reserved.
IP Address Review

5. 555© 2004, Cisco Systems, Inc. All rights reserved.
Subdividing the Host Octets of a Class C
Address

6. 666© 2004, Cisco Systems, Inc. All rights reserved.
Subdividing the Host Octets of a Class B
Address

7. 777© 2004, Cisco Systems, Inc. All rights reserved.
Subdividing the Host Octets of a Class A
Address

8. 888© 2004, Cisco Systems, Inc. All rights reserved.
Subnetting Chart (Bit Position and Value)

9. 999© 2004, Cisco Systems, Inc. All rights reserved.
Subnetting Chart (Subnet Mask Identifier)

10. 101010© 2004, Cisco Systems, Inc. All rights reserved.
Subnetting
Mascara /27: 11111111.11111111.11111111.11100000
255.255.255.224

11. 111111© 2004, Cisco Systems, Inc. All rights reserved.
Subnetting Chart

12. 121212© 2004, Cisco Systems, Inc. All rights reserved.
Subnetting Scheme

13. 131313© 2004, Cisco Systems, Inc. All rights reserved.
Find the Subnet Mask
255.240.0.0
255.255.255.224
255.255.255.248

14. 141414© 2004, Cisco Systems, Inc. All rights reserved.
Calculating the Subnet ID

15. 151515© 2004, Cisco Systems, Inc. All rights reserved.
The Logical ANDing Process

16. 161616© 2004, Cisco Systems, Inc. All rights reserved.
Finding the Answer Without Using Binary

17. 171717© 2004, Cisco Systems, Inc. All rights reserved.
EJEMPLO: 130.4.102.1, MASK 255.255.255.0

18. 181818© 2004, Cisco Systems, Inc. All rights reserved.
EJEMPLO: 130.4.102.1, MASK 255.255.255.0

19. 191919© 2004, Cisco Systems, Inc. All rights reserved.
TO FIND THE FIRST VALID IP ADDRESS IN THE SUBNET, COPY THE
SUBNET NUMBER, BUT ADD 1 TO THE FOURTH OCTET.
EJEMPLO: 130.4.102.1, MASK 255.255.255.0

20. 202020© 2004, Cisco Systems, Inc. All rights reserved.
THE LAST VALID IP ADDRESS IN THE SUBNET CAN BE CALCULATED
EASILY: COPY THE BROADCAST ADDRESS, EXCEPT SUBTRACT 1
FROM THE FOURTH OCTET.
EJEMPLO: 130.4.102.1, MASK 255.255.255.0

21. 212121© 2004, Cisco Systems, Inc. All rights reserved.
EJEMPLO :130.4.102.1, MASK 255.255.252.0

22. 222222© 2004, Cisco Systems, Inc. All rights reserved.
EJEMPLO :130.4.102.1, MASK 255.255.252.0

23. 232323© 2004, Cisco Systems, Inc. All rights reserved.
FIRST, YOU FIND IS THE MAGIC NUMBER — WHICH IS 256 MINUS THE MASK’S
INTERESTING OCTET. 256 – 252, MAGIC NUMBER OF 4.
THE MULTIPLE OF THE MAGIC NUMBER CLOSEST TO BUT NOT MORE THAN THE
ADDRESS’S INTERESTING OCTET IS THE SUBNET’S INTERESTING OCTET VALUE.
EJEMPLO :130.4.102.1, MASK 255.255.252.0

24. 242424© 2004, Cisco Systems, Inc. All rights reserved.
ADD THE MAGIC NUMBER TO THE INTERESTING OCTET VALUE OF THE
SUBNET NUMBER AND SUBTRACT 1. THE RESULT IS THE BROADCAST
ADDRESS’S VALUE IN THE INTERESTING OCTET. IN THIS CASE, THE VALUE
IS 100 + 4 (MAGIC NUMBER) – 1 = 103.
EJEMPLO :130.4.102.1, MASK 255.255.252.0

25. 252525© 2004, Cisco Systems, Inc. All rights reserved.
Determining Subnet, Broadcast Address and Valid Host Range
Example 1:
Host: 172.16.10.33 Subnet Mask: 255.255.255.224
Is this a Class A, Class B or Class C address?
Therefore how many bits make up the Network portion?
How many bits are in the Subnet Mask?
How many bits are left for Host addresses?
How many separate addresses in each subnet?
Which address represents the whole subnet?
Which address is used to broadcast to the subnet?
Which addresses are left in the valid host range?
First Valid: Last Valid:
Class B
16
11111111.11111111.11111111.11100000 = 27
5
32
172.16.10.32
172.16.10.63
172.16.10.33 172.16.10.62

26. 262626© 2004, Cisco Systems, Inc. All rights reserved.
Example 2:
Host: 192.168.100.25 Subnet Mask: 255.255.255.252
Is this a Class A, Class B or Class C address?
Therefore how many bits make up the Network portion?
How many bits are in the Subnet Mask?
How many bits are left for Host addresses?
How many separate addresses in each subnet?
Which address represents the whole subnet?
Which address is used to broadcast to the subnet?
Which addresses are left in the valid host range?
Determining Subnet, Broadcast Address and Valid Host Range

27. 272727© 2004, Cisco Systems, Inc. All rights reserved.
EJERCICIOS
• 172.31.100.100, mask 255.255.192.0
• 172.31.200.10, mask 255.255.248.0
• 192.168.100.100, mask 255.255.255.248

28. 282828© 2004, Cisco Systems, Inc. All rights reserved.
EJERCICIOS

29. 292929© 2004, Cisco Systems, Inc. All rights reserved.
EJERCICIOS

30. 303030© 2004, Cisco Systems, Inc. All rights reserved.
EJERCICIOS

31. 313131© 2004, Cisco Systems, Inc. All rights reserved.
Gracias por su atención …