TCP/IP Subnetting - Will Harper

standguideΔίκτυα και Επικοινωνίες

26 Οκτ 2013 (πριν από 4 χρόνια και 12 μέρες)

96 εμφανίσεις

Welcome to Back!


TCP/IP Subnetting

Pop Quiz

TCP/IP Cheat
Sheet

IP Addresses


My localhost
-
> 192.168.5.201


www.yahoo.com

-
> 87.248.113.14

IP Addresses

IP Address: 192.168.5.201

Network Portion:
192.168.5
.201

Node Portion: 192.168.5.
201



Every IP Address has a node portion and a
network portion

Subnet Mask

IP Address: 192.168.5.201

Subnet Mask:

255.255.255.0

----------------------------------------------------

Network ID: 192.168.5.0


The subnet mask tells us which part of an IP address
is the node portion vs. the network portion


An IP address without a subnet mask is meaningless

Binary ANDing


AND is a mathematical operator just like


+ (plus) and


(minus)


1 + 1 = 2


1
AND

1 = 1

AND Truth Table




A | B | A AND B

---------------------------------------

FALSE

|

FALSE

|

FALSE

FALSE

|

TRUE


|

FALSE

TRUE


|

FALSE

|

FALSE

TRUE


|

TRUE


|

TRUE

AND Truth Table



A B A AND B

-----------------------------

0


0


0

0


1


0

1


0


0

1


1


1

AND Truth Table



0 AND 0 = 0

0 AND 1 = 0

1 AND 0 = 0

1 AND 1 = 1

11000000101010000000010111001001

11000000.10101000.00000101.11001001

Man vs Machine


Human readable dotted decimal notation

192.168.5.201




Each number represents an “Octet” or 8 bits



What the computer sees:


Subnet Mask and ANDing


IP:



192.168.5.201


Subnet:

255.255.255.0

IP:


11000000.10101000.00000101.11001001

Subnet:

11111111.11111111.11111111.00000000

-----------------------------------------------



11000000.10101000.00000101.00000000



AND

IP:


11000000.10101000.00000101
.11001001

Subnet:

11111111.11111111.11111111.00000000

-----------------------------------------------



11000000.10101000.00000101
.00000000



TCP/IP Cheat Sheet: The Rules


The Subnet/network address is always
hidden behind the 1s in the mask

IP:


11000000.10101000.00000101
.11001001

Subnet:

11111111.11111111.11111111.00000000

-----------------------------------------------



11000000.10101000.00000101
.00000000



TCP/IP Cheat Sheet: The Rules


The Host/Node address is always hidden
behind the 0s in the mask

IP:


11000000.10101000.00000101
.
11001001

Subnet:

11111111.11111111.11111111.
00000000

-----------------------------------------------



11000000.10101000.00000101
.00000000



192.168.1.250= .11111010



--------------


1
0000000

192.168.1.5= .00000101



--------------


0
0000000

TCP/IP Cheat Sheet: The Rules

(Except in special cases)


The all
-
1s and all
-
0s
subnet
addresses
are invalid (but NOT in CIDR)

Ex.

Network ID

192.168.1.0

Subnet Mask 255.255.255.128
-
>

11111111
.
11111111
.
11111111
.
1
0000000

0s hide the
host
address

1s hide the
subnet address

Breaks the rule! (
except in CIDR
)

These bits belong to
the Big IP in the Sky

(we can’t change
them)

These are
the bits
that we
own

TCP/IP Cheat Sheet: The Rules

(Except in special cases)


The all
-
1s and all
-
0s
host
addresses are
invalid (Always)

Ex.

IP Address:



192.168.1.
0

Subnet Mask:


255.255.255.0

OR

IP Address:



192.168.1.
255

Subnet Mask:


255.255.255.0



Reason Behind the Rule


The all zeros host address is the same as
the network ID

Ex.


IP:

192.168.1.0



Subnet:

255.255.255.0

----------------------------------------

Network ID:

192.168.1.0



The all ones host address is reserved for
the broadcast address

Practice Problems


1 AND 1


1 AND 0


0 AND 1


0 AND 0


1111 AND 1010


0000 AND 1010


110101 AND 1101110

Practice Problems


110010b to Decimal


137d to Binary