Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 1 of 92

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 2 of 92 Networking TCP/IP IP Addressing and Subnetting Sandullah Epsicokhan

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 3 of 92 Converting IP addresses from binary to decimal If you’re given a 32 bit binary number, break it into four groups of eight bits each. Write As

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 4 of 92 Boolean AND operation The Boolean AND operation is a logical operation. It means exactly what it says. In order for the statement to be true we must have two things present.

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 5 of 92 Boolean AND operation For example if I said: “I have my right shoe and left shoe.” the statement would not be true if: –If I only had my left shoe. –If I only had my right shoe. –If I’m missing both shoes.

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 6 of 92 Boolean AND operation Similar logic is applied inside computers. Instead of shoes we use binary digits of 0 and 1. In computers the binary number 1 means we have something whereas the binary number 0 means we have nothing. Another way to look at it is that the binary number 1 means true in a binary number 0 means false.

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 7 of 92 Boolean AND operation Consider the following. –0 AND 0 = 0 –0 AND 1 = 0 –1 AND 0 = 0 –1 AND 1 = 1

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 8 of 92 Subnetting Practice AppA_CD.pdf on the Intro CD has 25 additional subnetting questions with answers. You can also check your results by using a subnet calculator.

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 9 of 92 Prefix notation Subnet masks made up of 1s and 0s. The 1s and 0s must be consecutive in a subnet mask. You cannot have 1s and 0s interspersed throughout the mask. The subnet mask always starts with 1s followed by 0s.

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 10 of 92 Prefix location Prefix notation is simply a slash (/) followed by the number binary 1s in a mask. For example: –Binary –Prefix notation /24 We say the subnet has a 24 bit prefix or a slash 24 prefix.

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 11 of 92 How many hosts, and how many subnets? Finding the sizes of the network, subnet, and host parts of the IP address. –The network part the address is always defined by class rules. –The host part of the address is always defined by the subnet mask. Binary 0s in the mask mean that the corresponding address bits are part of the host field. –The subnet part of the address is what’s left over in the 32 bit address.

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 12 of 92 Address Mask Number of network bits? Number of host bits? Number of subnet bits? How many hosts, and how many subnets?

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 13 of 92 Address Mask Number of network bits16 (Class B) Number of host bits 8 (Subnet mask has 8 zero bits) Number of subnet bits32 – (16 + 8) = 8 How many hosts, and how many subnets? NNNNNNNN. NNNNNNNN. NNNNNNNN. HHHHHHHH 8N8N8N8H 24N + 8H

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 14 of 92 Address Mask Number of network bits? Number of host bits? Number of subnet bits? How many hosts, and how many subnets?

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 15 of 92 Address Mask Number of network bits24 (Class C) Number of host bits 8 (Subnet mask has 8 zero bits) Number of subnet bits32 – ( ) = 0 No subnetting. How many hosts, and how many subnets? NNNNNNNN. NNNNNNNN. NNNNNNNN. HHHHHHHH 8N8N8N8H 24N + 8H

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 16 of 92 Understanding IP addressing Address Mask Number of network bits16 (Class B) Number of host bits 8 (Subnet mask has 8 zero bits) Number of subnet bits32 – (16 + 8) = 8 NNNNNNNN. NNNNNNNN. SSSSSSS. HHHHHHHH 8N8N8S8H 24N + 8H

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 17 of 92 Understanding IP addressing Address Mask Number of network bits? Number of host bits? Number of subnet bits? NNNNNNNN. NNNNNNNN. NNNNNNNN. SSSSSSSH 8N8N8N8H 24N + 7S + 1H

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 18 of 92 Key methods Convert the mask binary, using any method for conversion at your disposal, and count the number of zeros. Convert the mask to binary after memorizing the nine decimal and binaries values and tables 12-8 Create your own binary conversion table. How many hosts, and how many subnets?

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 19 of 92 Subnetting formulas Number of subnets = 2 (number-of-subnet bits) -2 Number of hosts per subnet = 2 (number-of-hosts-bits) -2

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 20 of 92 Create a decimal conversion table When working with binary numbers and octets, one way to do the math is the start with a decimal conversion table. Start by creating the following table.

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 21 of 92 Create a decimal conversion table Bit Counts Table S-1 Number of bits in a byte

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 22 of 92 Create a decimal conversion table Table S-2 Value of each bit (working from right to left) Bit Counts Power

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 23 of 92 Create a decimal conversion table Bit Counts Power Decimal Value Table S-3 Decimal Value of the powers of two. Each is twice as much as the bit to the left.

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 24 of 92 Align the binary number to the table Bit Counts Power Decimal Value Binary Number Table S-4 Align the bits to the decimal values.

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 25 of 92 Keep the decimal values where the number 1s appear Then add the results Bit Counts Power Decimal Value Binary Number Result Sum = 150 Table S-5 Multiple the binary value times the decimal value above it. Then add up the result.

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 26 of 92 Exercise 1: Build the conversion table Exercise S-1 Build the conversion table

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 27 of 92 Exercise 1: Build the conversion table Bit Counts Power Exercise S-1 Lay out the bit positions

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 28 of 92 Exercise 1: Build the conversion table Bit Counts Power Decimal Value Exercise S-1 Double the values

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 29 of 92 Exercise 2: Convert to decimal

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 30 of 92 Exercise 2: Convert to decimal Bit Counts Power Decimal Value Binary Number Result Sum 0 Table S-5 Multiple the binary value times the decimal value above it. Then add up the result.

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 31 of 92 Exercise 3: Convert to decimal

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 32 of 92 Exercise 3: Convert to decimal Bit Counts Power Decimal Value Binary Number Result Sum = 83 Table S-5 Multiple the binary value times the decimal value above it. Then add up the result.

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 33 of 92 Exercise 4: Convert to decimal

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 34 of 92 Bit Counts Power Decimal Value Binary Number Result Sum = 255 Table S-5 Multiple the binary value times the decimal value above it. Then add up the result. Exercise 4: Convert to decimal

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 35 of 92 Exercise 5: Convert to decimal

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 36 of 92 Bit Counts Power Decimal Value Binary Number Result Sum = 173 Table S-5 Multiple the binary value times the decimal value above it. Then add up the result. Exercise 5: Convert to decimal

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 37 of 92 Convert decimal to binary If X is a number we wish to convert from decimal to binary, perform the following steps building the binary number from right to left until X = If X is odd, write down the number “1” and subtract 1 from X. 2. If X is even, write down “0”. 3. Divide X by Go back to step 1 using the result from step 3.

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 38 of 92 Convert decimal to binary For example, let's take the decimal value 157: = 156,156 ÷ 2 = = 78, 78 ÷ 2 = = 38, 38 ÷ 2 = = 18, 18 ÷ 2 = = 8, 8 ÷ 2 = = 4, 4 ÷ 2 = = 2, 2 ÷ 2 = = 0, Result from bottom up

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 39 of 92 Bit Counts Power Decimal Value Masks Build a subnetting table Table S-5 Add current subnet value to current decimal value

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 40 of 92 Bit Counts Power Decimal Value Masks Build a subnetting table Table S-5 Add current subnet value to current decimal value

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 41 of 92 Bit Counts Power Decimal Value Masks Build a subnetting table Table S-5 Add current subnet value to current decimal value

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 42 of 92 Bit Counts Power Decimal Value Masks Build a subnetting table Table S-5 Add current subnet value to current decimal value

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 43 of 92 Bit Counts Power Decimal Value Masks Build a subnetting table Table S-5 Add current subnet value to current decimal value

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 44 of 92 Bit Counts Power Decimal Value Masks Build a subnetting table Table S-5 Add current subnet value to current decimal value

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 45 of 92 Bit Counts Power Decimal Value Masks Build a subnetting table Table S-5 Add current subnet value to current decimal value

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 46 of 92 Bit Counts Power Decimal Value Masks Build a subnetting table Table S-5 Add current subnet value to current decimal value

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 47 of 92 Bit Counts Power Decimal Value Masks Build a subnetting table Table S-5 Add current subnet value to current decimal value

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 48 of 92 Bit Counts Power Decimal Value Masks Build a subnetting table Table S-5 Add current subnet value to current decimal value

Subnetting Tips - CCNA Power Camp, Ver Copyright 2005, Epsico 49 of 92 Questions?