1. Optimizing IP Address Allocation

2. Overview Classless Inter-Domain Routing (CIDR ) Binary IP Addresses
Binary Subnet Masks
IP Address Allocation Using CIDR

3. Classless Inter-Domain Routing (CIDR)
Limitations of Classful IP Addressing
Defining CIDR

4. Limitations of Classful IP Addressing
Adds Multiple Entries to Routing Tables
Class C w x y z
Network ID
Host ID
255
Portion of Internet Routing Tables
Company Network IDs
Internet
Wastes IP Addresses
Network of 2000 Computers
Assigned 65,534 IP Addresses
63,534
Wasted
2000
Allocated
Class B w x y z
Network ID
Host ID
255

5. IP Address in Binary Notation
Defining CIDR w x y z
IP Address in Dotted Decimal Notation
Network ID
Host ID
32 Values
4 Values
IP Address in Binary Notation

6. Binary IP Addresses Converting to Binary Format
Converting to Binary Format Using a Calculator

7. Converting to Binary Format
Binary Notation (Base 2) 27 26 25 24 23 22 21 20
Example 1
1*128
1*64
0*32
1*16
1*8
0*4
0*2
1*1
128 64 32 16 8 4 2
217
8 Bits
Decimal Value 255 1
128 64 32 16 8 4 2
Decimal Notation (Base 10)
104
103
102
101
100
10,000
1,000 10 1
Example 2 7
0*104
2*103
1*102
7*101
200
217

8. Converting to Binary Format Using a Calculator
Edit View Help
Hex
Dec
Oct
Bin
Degrees
Radians
Grads
Inv
Hyp
Backspace CE C
Sta
Ave
Sum s
Dat
F-E
dms
sin
cos
tan [ ]
Exp In
x^y
log
x^3
x^2 nl
1/x pi M+ MS MR MC 7 8 9 4 5 6 1 2 3
+/- . A B D E F / * - + =
Lsh Or
Mod
And
Xor
Not
Int 0.
Hex
Decimal
Octal
Binary
Degrees
Radians
Grads
Digit grouping F5 F6 F7 F8 F2 F3 F4
Scientific
Standard

9. Binary Subnet Masks Subnet Mask Bits CIDR Notation
Calculating the Network ID
Determining Local and Remote Hosts

10. Binary Representation Decimal Representation
Subnet Mask Bits
Binary Representation
Decimal Representation
255
254
252
248
240
224
192
128
Network ID
Host ID 1 w x y z

11. CIDR Notation IP
Address
Subnet
Mask
Number of Subnet Mask Bits (ones)
IP Address in
CIDR Notation
= 20
/20

12. Calculating the Network ID
IP Address in CIDR Notation: /20 IP
Address
Subnet
Mask
Network ID
Network ID in
CIDR Notation
/20

13. Determining Local and Remote Hosts
Remote Host Example 1 2
Router A B C D E F
/20
/ 20
Local Host Example 1 2
Router A B C D E F
/10
/10

14. IP Address Allocation Using CIDR
Available Host IDs
Optimizing the Allocation of IP Addresses

15. Available Host IDs Subnet Mask N Number of Host IDs : 2n - 2
Network ID
Host ID 1

16. Optimizing the Allocation of IP Addresses
After Subnetting
Router B
Router A
Routing Table for Router B
Routing Table for Router B
Before Supernetting:
Router A
Router B
Routing Table for Router B
Router B
Router A
After Supernetting:

17. Review Classless Inter-Domain Routing (CIDR ) Binary IP Addresses
Binary Subnet Masks
IP Address Allocation Using CIDR