“We are only as strong as we are united, as weak as we are divided.”
– Albus Dumbledore, Harry Potter and the Goblet of Fire, Chapter 37
We covered static routing in previous tutorials. We attempted to configure a network with the network address 192.168.300.0/24 at the start of the tutorials. We discovered the hard way that we couldn’t use it as a network address. An IP address is a string of numbers separated by periods. IP addresses are expressed as a string of four numbers, such as 192.158.1.38. Each number in the set can have a value ranging from 0 to 255. As a result, the full IP addressing range is 0.0.0.0 to 255.255.255.255. We cannot have an IP address where an octet is greater than 255.
We had to reconfigure the network to solve this issue. We also reconfigured the other networks for our convenience. Network administrators are always configuring and reconfiguring networks.
When we have three or four networks, we can continue to use static routing. When the network size reaches, say, 20, this strategy is no longer efficient. And the number of networks that are linked is always increasing.
Consider the following scenario to get a sense of why static routing does not scale.
You are a network administrator. One day, you receive a letter from Hogwarts School of Witchcraft and Wizardry Headmaster Albus Dumbledore.
You accepted the job. Hogwarts School, located somewhere in the Highlands of Scotland, was made up of the massive Hogwarts Castle and the extensive school grounds that surrounded it.
Importance of Unity
Hogwarts Castle is a large, seven-story-tall magically supported structure with a hundred and forty-two staircases throughout its many towers and turrets and very deep dungeons.
It is your responsibility to set up and manage networks in the following areas:
Gryffindor Tower Slytherin Dungeon Hufflepuff Common Room Ravenclaw Tower Headmaster's Tower North Tower Stone Bridge Tower West Tower Central tower Founders' Tower Herbology tower Left Long Gallery tower Right Long Gallery tower Suspension Bridge towers Second-floor girls' lavatory tower Training Grounds tower Astronomy Tower Bell towers Turris Magnus Turris Medius
Network Scaling for Dynamic ROuting
You must set up at least 20 different LANs.
When establishing a LAN network, the following items are required: crossover Ethernet cables, Ethernet cables, Ethernet switch or switches, and network interfaces. To connect the LANs you will also need routers and serial cables(you can also use ethernet cables or crossover ethernet cables).
When it comes to networks, planning is everything. Since the beginning of this course, you’ve learned a great deal about networking. You’ve learned how to set up physical cable networks, how hubs, switches, and routers work, how to make the most of your intelligent network devices, and how to troubleshoot even the most difficult network problems. It’s finally time to put everything you’ve learned into action and see how far you’ve come on your networking journey. We believe in you!
You essentially reran some cables and installed some trays in an earlier tutorial. However, the challenge here is to plan all aspects of a network on a building that is currently only a rough floor plan.
When there isn’t even a blueprint, just an idea, this is the best time to get started with your network design. You can ensure that the network you design will meet the needs of the building’s occupants while also allowing for future growth.
At this early stage, the most important thing to do is to talk to people. Speak with the future occupants, the teachers, and your IT staff. Collect as much information as possible. With all of this information at your disposal, you can make informed decisions about your network design.
A network design includes:
- Physical layout of wire and network drops
- Network hardware configuration
- Logical network design
- An implementation plan
Network Design
Let’s get started right away and make a plan of action. Take note of the order of the steps.
So you’ve set up 20 LANs and connected them together with Routers. Each LAN is directly connected to at least one other LAN and indirectly connected to all the others via a web of fiber optic cables. Gryffindor Tower, for example, is directly connected to three other LANs (Hufflepuff Common Room, Ravenclaw Tower, and Headmaster’s Tower) and indirectly connected to all the others.
Enter all of the network addresses to which you want your router to be able to send traffic. You have to do this for each router(remember the three routing protocols discussed earlier). You did this, and now all of the networks are operational. They can also communicate with one another using the route in their routing tables.
All goes well for a while. The Gryffindor Tower’s routing table has been filled with all of the static routes to the other LANs, but network traffic isn’t getting through to one of them. So, what’s the problem? You must investigate the issue.
So, what exactly is the issue with the network connection?
Unfortunately for Gryffindor Tower, it appears that Slytherin Dungeon and Astronomy Tower changed the network address assigned to their routers. Because the Gryffindor Tower router only had the old network addresses as a static route in the routing table, the router no longer knew where to send network traffic destined for these two networks.
When routes change, you must modify those routes in your router’s route table to keep it up to date.
So how do we fix this?
That is simple. All we need to do is update the route in the routing table to reflect the new network addresses.
Static routes do not change automatically. This means that if you have static routes in your routing table, you must manually change them.
What kind of issues do you anticipate with this?
Wouldn’t it be much easier if you just “taught” the routers how to get from one point to another? Dynamic routing protocols would be the solution to this problem.
Use RIP to prompt routes to update. If you want to make your life easy, spend some time setting up a dynamic routing protocol on your network. One such dynamic routing protocol is RIP, or Routing Information Protocol. Routers use RIP to share network addresses. Routers use RIP to communicate with one another, sharing route information and keeping route tables up to date.
The next lesson discusses RIP.
