Posts Tagged ‘ subnet ’

ANDing IP Address Subnets 22 July 2008 at 10:35 am by admin
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ANDing: (Boolean and)

Computers use digital logic to interpret IP addresses
This logic is called a Boolean AND. It is the comparison of two bits to yield:

1 & 1 = 1
1 & 0 = 0
0 & 1 = 0
0 & 0 = 0

Any # ANDed with 0 is always 0
Any # ANDed with 1 is always the original #
The ANDing of an IP address & mask = network address
A subnet mask “masks” the host bits of an IP address
Routers and hosts use ANDing to determine networks
It is frequently necessary to be able to use ANDing
You will need to know how routers make routing decisions
Start with the IP address & mask above/below each other

10101100.00010000.00010100.00100011 172.16.24.35 (Host)
11111111.11111111.11111111.111 00000 255.255.255.224
——————————————————
10101100.00010000.00010100.00100000 172.16.23.32 (network address for
host /27)

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Tags: vlan, ip, wan, cisco, study, switch

+ IP addressing By admin 16 July 2008 at 11:53 pm and have Comments Off

IP Addressing Structure:
IPv4 Address = 32 bit # written as dotted decimals
Always paired with a 32 bit mask
Computers evaluate &
E.G. 10101000 <- high-order that side, -> low order this side.

Network = group of hosts with identical network addresses.
Some portion of the low-order bits = host address.
From our 32 bits, the # of bits used in the host portion determines how many hosts we can have in our network.
E.G. if 200 hosts in our network. We need enough bits in the host portion to make 200+ numbers
2^7 = 128, 2^8 = 256, therefore 8 bits minimum are required to get 200+ hosts.

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Tags: vlan, cisco, switch, ip, router, wan

+ Calculating VLSM subnetworks By admin 23 June 2008 at 12:43 pm and have Comments Off

Bitmindframes cisco study guides.

Calculating VLSMs

Scenario: Your company has been given the network address 172.16.32.0/19.

10101100 . 00010000 . 001 00000 . 00000000

After careful planning, looking at current needs and expansion, you realize you need a maximum of three subnets of 1,000 hosts, three subnets of 250 hosts, and several subnets for serial point-to-point links.

There are several ways to do this, but you have decided that you will variably subnet your network as follows: (We did it this way just for the exercise and to keep it somewhat simple.)

Step 1 : The maximum number of hosts any of your subnets will need is 1,000, so you decide to make the initial subnets 172.16.32.0/22. Write out the eight /22 subnets in binary and decimal form:

1. 10101100 . 00010000 . 001 000 00 . 00000000 172.16.32.0/22

2. 10101100 . 00010000 . 001 001 00 . 00000000 172.16.36.0/22

3. 10101100 . 00010000 . 001 010 00 . 00000000 172.16.40.0/22

4. 10101100 . 00010000 . 001 011 00 . 00000000 172.16.44.0/22

5. 10101100 . 00010000 . 001 100 00 . 00000000 172.16.48.0/22

6. 10101100 . 00010000 . 001 101 00 . 00000000 172.16.52.0/22

7. 10101100 . 00010000 . 001 110 00 . 00000000 172.16.56.0/22

8. 10101100 . 00010000 . 001 111 00 . 00000000 172.16.60.0/22

Step 2 : You only need three /22 subnets, so you reserved the first three for those subnets needing 1,000 hosts. Which ones are they?

1. 10101100 . 00010000 . 001 000 00 . 00000000 172.16.32.0/22

2. 10101100 . 00010000 . 001 001 00 . 00000000 172.16.36.0/22

3. 10101100 . 00010000 . 001 010 00 . 00000000 172.16.40.0/22

Step 3 : You decide to sub-subnet the fourth subnet (172.16.44.0/22) for the three subnets each needing 250 hosts. A /24 will work well for this. What are the three /24 sub-subnets you will use?

4. 10101100 . 00010000 . 001 011 00 . 00000000 172.16.44.0/22

4a. 10101100 . 00010000 . 001 011 00 . 00000000 172.16.44.0/24

4b. 10101100 . 00010000 . 001 011 01 . 00000000 172.16.45.0/24

4c. 10101100 . 00010000 . 001 011 10 . 00000000 172.16.46.0/24

4d. 10101100 . 00010000 . 001 011 11 . 00000000 172.16.47.0/24

Step 4 : The last (fourth) of the /24 sub-subnets (172.16.47.0/24), you decide to use for you serial point-to-point links. List the first five /30 sub-sub-subnets (if there is such a term):

4d. 10101100 . 00010000 . 001 011 11 . 00000000 172.16.47.0/24

4d1.10101100 . 00010000 . 001 011 11 . 000000 00 172.16.47.0/30

4d2.10101100 . 00010000 . 001 011 11 . 000001 00 172.16.47.4/30

4d3.10101100 . 00010000 . 001 011 11 . 000010 00 172.16.47.8/30

4d4.10101100 . 00010000 . 001 011 11 . 000011 00 172.16.47.12/30

4d5.10101100 . 00010000 . 001 011 11 . 000100 00 172.16.47.16/30

etc.

4d5.10101100 . 00010000 . 001 011 11 . 111111 00 172.16.47.252/30

Tags: ip, switch, study, interface

+ cisco vlan’s extended & standard ranges By admin 18 June 2008 at 6:26 pm and have Comments Off

Bitmindframes cisco study guides.

VLAN’s are a very useful tool in an enterprise network,they segment each departments data using a single switch and trunking.

Here we will discuss the basics of VLAN’s in a cisco internetwork.

A VLAN is a logically separate IP subnetwork. VLANs allow multiple IP networks and subnets to exist on the same switched network. The figure shows a network with three computers. For computers to communicate on the same VLAN, each must have an IP address and a subnet mask that is consistent for that VLAN. The switch has to be configured with the VLAN and each port in the VLAN must be assigned to the VLAN. A switch port with a singular VLAN configured on it is called an access port.

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