Computer Networks Sessional Lab-7 and 8 VLSM,CIDR and Summary routes

1. Computer Networks SessionalLab-7 and 8VLSM,CIDR and Summary routes Instructor: SazidZaman Khan Lecturer, Department of Computer Science and Engineering, IIUC

2. Objective • To understand and implement VLSM, CIDR and summary routes.

3. DCE • Data Communications Equipment (DCE) can be classified as equipment that transmits or receives analogue or digital signals through a network. DCE works at the physical layer of the OSI model taking data generated by Data Terminal Equipment (DTE) and converting it into a signal that can then be transmitted over a communications link. • A general rule is that DCE devices provide the clock signal (internal clocking) and the DTE device synchronizes on the provided clock (external clocking)

4. DTE • Data Terminal Equipment (DTE) is any equipment that is either a source or destination for digital data. DTE do not generally communicate with each other to do so they need to use DCE to carry out the communication. DTE does not need to know how data is sent or received; the communications details are left to the DCE.

5. WIC 2T • The dual-serial port WAN interface cards (WICs) for the Cisco 2600 and 1700 series feature Cisco`s Smart Serial connector to support a wide variety of electrical interfaces when used with the appropriate transition cable. Two cables are required to support the two ports on the WIC. Each port on a WIC is a different physical interface.

6. Experimental procedure • 1. Take four 1841 routers and name them R1 to R4 as shown below:

7. Experimental procedure • 2. Go to R1 router, turn it off and add 2 serial WIC 2T interfaces, then turn it on again as shown below.

8. Experimental procedure • 3. So for router R1, you have 2 Ethernet and 4 serial interfaces.

9. Experimental procedure • 4. Go to R2 router, turn it off and add 1 serial WIC 2T interfaces, then turn it on again as you did with R1. • 5. Take two 2960-24TT switches and connect them (their fa 0/1s) with fast ethernet ports (fa 0/0 and fa 0/1) of the R1 router. Shown below:

10. Experimental procedure

11. Experimental procedure 6. Connect R1 and R2 with the serial interface, so that R1 provides the clock signal (R1 is DCE). To do this take the serial DCE cable, click on R1 Se 0/0/0 first and then click on R2 Se 0/0 as shown below:

12. Experimental procedure

13. Experimental procedure • Give the network between R1 and R2 the following IP: 173.16.71.4/30 as shown:

14. Experimental procedure • 7. Note that it’s a classless address, so the network address is: 173.16.71.4/30= 10101101 00010000 01000111 00000100 • So, the first (host) address of this network is: • 10101101 00010000 01000111 00000101= • 173.16.71.5 • and the second (host) address is = 173.16.71.6 and what about the broadcast address? • I guess you understand.

15. Experimental procedure • 8. So assign the address 173.16.71.5 to R1 and assign the address 173.16.71.6 to R2 together with the subnet mask (can you tell what will be the subnet mask?) as shown below (R1 is shown). Assign clock rate and type no shutdown (to up the interface).

16. Experimental procedure • 9. Give labels to the networks between the two switches and the router as shown below:

17. Experimental procedure • 10. Configure the fast ethernet interface of R1 connected to the switches as below (notice the addresses are assigned from the router-switch network’s address range)

18. Experimental procedure (route summarization) • 11. Now if R2 wants to talk with the switch1-R1 and switch2-R2 network it could put two static routes in its routing table. • A better option for R2 is to put the summary route of 173.16.66.0/23 and 173.16.64.0/23 based on the longest prefix match. This is route summarization as we read before midterm. In this way, R2 has to put just one route instead of 2 in it’s table.

19. Experimental procedure (route summarization)

20. So tell me what’s the summary address?

21. Here it is (because 173.16.64.0/22 covers 173.16.64.0, 173.16.65.0, 173.16.66.0 and finally 173.16.67.0-see binary of 173.16.64.0/22 )

22. So let’s tell our router (R2) how to go to that summary network using static route entry

23. So is your added route working? • Can you test whether you added route is working?(Lab bonus +2)

24. This is how you test the added route is working or not • Take two PCs attach with switch1 and switch 2. • Assign appropriate IP, subnet and gateway (for PC0 it’s shown on next slide), assign these for PC1 too. • Then try ping from router R2 to PC0 and PC1.

25. This is how you test the added route is working or not (notice the gateway)

26. This is how you test the added route is working or not (notice the gateway)

27. Second part • Add the following devices as shown in figure, connect the switches to R2 with fast Ethernet ports serially and straight through cables.

28. Assign IP to PCs (shown for PC 2)

29. Assign IP to the fast ethernet ports 0/0 and 0/1(configure it as the gateway)

30. Find summary route for two LANs on R2

31. The summary route is

32. Put that summary route on the table of R1

33. Watch the configuration of router with show run command

34. Look at the routing table of your router using the command show ip route

35. Routing table explained • C means connected route and S means static route.

36. So try ping from PC1 to PC3

37. Finally, after these labs, your topology should look like this