Archive for the ‘Routing’ Category
June 27th, 2008 | 
Author: Bitmindframes cisco study guides
INTERVLAN ROUTING
A VLAN is a broadcast domain and unique ip subnet
Switches operate at layer2 (Data link Layer)
VLANS cannot communicate without L3 (Network Layer)
The L3 communication is called inter-vlan routing
Inter-vlan routing is a process of forwarding network traffic from one vlan to another using a router
The Subnets of your network facilitate the routing process.
Router interfaces can be connected to separate vlans.
Devices on vlans send traffic through the router(L3) to other vlans.
Traditionally vlan routing required multiple interfaces.
Each interface was connected to a separate switch port & configured with a different subnet
The switch port is connected to the router in access mode.
Tags: study, 802.1q, vtp, router, cisco, guides
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