> | Lab 3.3.12.1 WAN commands - overview Estimated time: 60 min. Objectives: Explore the WAN capabilities of the router Use the terminology from the semester 4 online chapters on WANs. Experiment with some WAN related IOS commands Background: LANs vs. WANs: This lab is an introduction to Wide Area Networks (WANs) and the part routers play in them. Local Area Networks (LANs) typically consist of a group of computers that are interconnected with hubs or switches using physical cable (twisted pair copper and multimode fiber). WANs are made up of two or more LANs that are geographically separate sites. They typically use services provided by a long distance carrier with transmission over Fiber or Microwave to connect the sites. An organization can own the equipment that interconnects its WAN sites but most often leases WAN links from a service provider. Routers and WANs: Although routers can be used to subdivide campus LANs to limit the size of broadcast domains and help maintain security, they are most commonly used to interconnect LANs to make WANs. The router is the interface or gateway from the LAN to the WAN. With most organization's WANs, each location will have at least one router with an interface or link to one or more other locations in the WAN. This is usually done through a CSU/DSU (Channel Service Unit / Data Service Unit). Even small organizations with a single location today need a router to connect them to the largest WAN in the world, the Internet. WANs and the OSI Model: WAN links typically operate at OSI Layer 2 (Data Link) and convert the LAN frame encapsulation such as Ethernet or Token Ring to a wide area Layer 2 frame encapsulation such as HDLC, PPP or Frame Relay. As an example, let's say you have two Ethernet LANs interconnected by a WAN link (such as a T1) and a workstation in LAN A needs to connect to a server in LAN B. The workstation sends a packet to the Ethernet interface (e.g. E0) of the router in LAN A. That router removes the Ethernet LAN frame header, replaces it with a WAN frame header such as Frame Relay or PPP and sends it out one of its serial interfaces (e.g. S0). When the router on LAN B receives the packet on its serial interface, it strips off the WAN frame header and replaces it with the LAN Ethernet frame header. The packet is delivered to the local server on LAN B through the router's Ethernet interface. Tools / Preparation: Prior to starting the lab, the teacher or lab assistant should have the standard router lab with all 5 routers set up. Before beginning this lab you should read the Networking Academy Second Year Companion Guide, Chapters 8 and 9 on WANs and WAN Design. You should also review Semester 4 On-line chapters WANs and WAN Design. Work individually or in teams. The following is a list of resources required. Standard Cisco 5-router lab setup with hubs and switches Workstation connected to the router's console port Router Manuals and access to the Cisco web site Web Site Resources: Routing basics General information on routers 2500 series routers 1600 series routers Terms and acronyms IP routing protocol IOS command summary Introduction to WAN technologies Step 1 – Review router lab WAN physical connections The standard 5-router lab setup uses WAN serial cables to simulate three wide area network connections between four of the routers (A,B,C and D). These four routers could all belong to corporation XYZ and could be located in different cities across the United States (e.g. Lab-A = Anaheim, CA., Lab-B = Boise, ID, Lab-C = Chicago, IL., Lab-D = Dallas, TX.). Routers D and E are attached to a common Ethernet LAN. Normally the cable from the router in each location would connect to a CSU/DSU (Channel Service Unit / Data Service Unit) and then to a WAN link such as a T1 (1.544Mbps) from a service provider. With some routers, the CSU is built-in or can be installed in a modular slot. One end of each cable is a DB60 (60-pin) connector that attaches to a synchronous serial interface on the router (S0 or S1 in most cases). The other end is a V.35 connector that normally attaches to the CSU/DSU. The CSU/DSU then connects to the digital data line (such as a 56K or T1 link) via a NIU (Network Interface Unit) at the Demarc (demarcation point). This is the separation point between CPE (Customer Premises Equipment) and the WAN link service provider's connection. The standard 5-router lab setup simulates the CSU/DSUs on Point-to-Point WAN links by crossing the connections between the V.35 cables which eliminates the need for the CSU/DSUs. The Router is typically the DTE (Data-circuit Terminating Equipment) and the CSU/DSU is normally the DCE (Data Communication Equipment). Since there is no CSU/DSU, one of the routers on each simulated WAN link must play the role of the DCE in order to provide the synchronous clocking signal. With the standard lab setup, router Lab-A Serial interface 0 is the DCE and the clock rate is set to 56000 bps on that interface, simulating a 56K digital data circuit. You must attach the DCE (female) cable to this router interface. The DTE (male) serial cable is attached to the Serial 1 interface on the next router Lab-B. No clock is set on the Lab-B S1 interface. Serial interface S0 on router Lab-B then becomes the DCE for the next router. Step 2 - Identify the router lab WAN connections Use the standard lab diagram to identify the Wide Area Network (WAN) links. Fill in the table below with WAN information contained in the diagram including the number of the WAN IP network between each pair of routers, the router names that have WANs between them, the interfaces in use on each router and the characteristics of the WAN interface cable. Fill in the following WAN connection table
> WAN IP Network number | Connects FROM Which Router and Interface | DCE or DTE? | Connects TO Which Router and Interface | DCE or DTE?
> Step 3 - Diagram the lab WAN connections Use the standard lab diagram as a starting point and draw the physical and logical WAN topology of the existing lab setup. The main purpose is to identify the routers and Wide Area Network (WAN) links. Identify and label all WAN connections (i.e., identify DCE and DTE cables and clock rate etc. Diagram the WAN links and their characteristics in the standard lab setup
Step 4 - Review WAN Connection Options Refer to the Cisco on-line documentation and the hardware manuals such as the Cisco 2500 Installation and Configuration Guide for the routers you are working with. What are common options or types of Router WAN connections? (Hint: See question 4) What Router features and/or additional hardware would you need to use ISDN, PPP, Frame-Relay or Dial-up WAN Connections? Step 5 - Review WAN encapsulation types The frame encapsulation used at the Data Link Layer (OSI Layer 2) will vary depending on the WAN technology used between networks connected by routers. The Data Link encapsulation places a header and trailer on the packet. Layer 2 framing on a LAN is different than a WAN and the router must convert between the two. Check the WAN encapsulation on Lab-A serial interface 0 using the following command: Router# show interface s0 What is the default WAN encapsulation currently in use on the interface between Routers Lab-A and Lab-B? To see what WAN encapsulation options are available, us the following commands: Router(config)# interface Serial 0 Router(config-if) #encapsulation ? What are some of the Data Link layer WAN encapsulation types available? Step 6 - Using WAN Related Router Commands The following router show commands can help to explore the WAN capabilities of the router. On a router with standard configurations, try the following show commands from the privileged EXEC mode, note the results, and answer the questions. Show interfaces What does this command tell you about WAN connections? Show int s0, show int s1, show int bri0, show int e0, show int e1 etc. What do these commands tell you about WAN connections? Show protocols What does this command tell you about WAN connections? Show ip route What does this command tell you about WAN connections? Show cdp neighbors What does this command tell you about WAN connections? Step 7 - Exploring WAN protocol commands Try some of these additional WAN protocol related commands. Be sure use a space and a ? at the end of the command to see the options available. If the WAN option is not available you will not get an error but no information will be displayed. Write down some of the options that are displayed. Show frame- relay ? Show dialer ? Show ppp ? Show smds ? Show x25 ?