Subnetting

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IP ADDRESSING AND SUBNETTING

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• 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

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IP Address Review

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IP Address Review

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Subdividing the Host Octets of a Class C Address

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Subdividing the Host Octets of a Class B Address

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Subdividing the Host Octets of a Class A Address

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Subnetting Chart (Bit Position and Value)

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Subnetting Chart (Subnet Mask Identifier)

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Subnetting

Mascara /27: 11111111.11111111.11111111.11100000 255.255.255.224

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Subnetting Chart

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Subnetting Scheme

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Find the Subnet Mask

255.240.0.0

255.255.255.224

255.255.255.248

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Calculating the Subnet ID

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The Logical ANDing Process

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Finding the Answer Without Using Binary

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EJEMPLO: 130.4.102.1, MASK 255.255.255.0

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EJEMPLO: 130.4.102.1, MASK 255.255.255.0

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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

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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

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EJEMPLO :130.4.102.1, MASK 255.255.252.0

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EJEMPLO :130.4.102.1, MASK 255.255.252.0

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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

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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

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Determining Subnet, Broadcast Address and Valid Host Range

Example 1: Host: 172.16.10.33 Subnet Mask:

255.255.255.224Is 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

32172.16.10.32

172.16.10.63

172.16.10.33 172.16.10.62

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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

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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

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EJERCICIOS

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EJERCICIOS

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EJERCICIOS

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