| Lab 4.3.4 PPP configuration - overview Estimated time: 60 min. Objectives: Understand how WAN encapsulation types affect synchronous serial connections Convert from HDLC to PPP encapsulation on a WAN connection Use the terminology of the semester 4 online lesson on WANs. Background: This lab focuses on PPP (Point-to-Point Protocol). PPP is a Wide Area Network (WAN) protocol that provides OSI layer 2 (data-link layer) services for router-to-router and host-to-network connections (over synchronous and asynchronous circuits) using a serial interface. It is commonly used by PCs to connect to an Internet Service Provider (ISP) via a dial-up phone line (asynchronous host-to network) or as a WAN encapsulation method between LANs (synchronous router-to-router). PPP is an international, standardized and widely used protocol developed by the Internet Engineering Task Force (IETF). PPP is considered a part of the TCP/IP protocol suite and supports a number of LAN protocols such as IP and IPX and various methods of security authentication such as PAP and CHAP. PPP can be used on various physical media, including twisted pair, fiber or satellite transmission. It uses a variation of High-Speed Data Link Control (HDLC) for packet encapsulation. Synchronous Serial Ports: Nearly all Wide Area Network (WAN) links used with Internetwoks are "serial" meaning they transmit bits one after another in a series along a wire or fiber cable. Routers have Synchronous serial ports for WAN connections. They are not the same as the Asynchronous serial connection ports found on PCs and are capable of much higher data rates. Most routers have at least one Synchronous serial port for WAN connection and two Asynchronous serial ports; a Console port for local connection and an AUX port for remote configuration of the router. The Wide Area Network connections between the routers in the standard Cisco lab setup are synchronous serial links. Speeds for serial digital WAN links can range from a 56Kbps circuit to a T1 (appx. 1.5 Mbps) or a T3 (appx. 45 Mbps). When setting up the serial WAN links for the router lab, the default layer 2 encapsulation is a Cisco proprietary version of High-Level Data Link Control (HDLC) protocol. PPP is more standardized, providing better security and support for dialup connections. With this lab you will convert the WAN links between the lab routers from HDLC to PPP. The PPP encapsulation must be set on both ends of the WAN connection. 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, Chapter 10 on PPP. You should also review the Semester 4 On-line chapter on PPP. Work individually or in teams. The following is a list of resources required. Standard Cisco 5-router lab setup with hubs and switches 2 routers with WAN link between them and HDLC encapsulation (default) Workstation connected to the router's console port Router Manuals 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 Notes: Select a pair of routers which have a WAN serial link between them such as Lab-A and Lab-B before starting the lab. You could also use Lab-B and Lab-C or Lab-C and Lab-D. Connect your workstation to the console port connection of the first router (Lab-A). Step 1 - Use the lab diagram and show running-config command to answer the following questions about the Lab-A router: Lab-A# show running-config Which Serial interface is used for the WAN link? What is the IP address of this interface? What is the subnet mask of this interface? Is this interface a DCE or DTE connection? How do you know if it is DCE or DTE? What is the clock rate set for this interface? What is the bandwidth set for this interface (if set)? What would the bandwidth be set to if this were a T1 interface? Step 2 - Examine the WAN cables attached to Router Lab-A and answer the following questions: Which interface is the cable attached to on Router Lab-A? What type of physical connector connects to the serial port on the router? What type of physical connector is on the other end of the cable? Step 3- Use the show interface command and answer the following questions: Lab-A# show interface serial 0 What is the status of the interface and the Line protocol? How is the IP address and Subnet mask displayed? What is the Maximum Transmission Unit (MTU)? What is the bandwidth set to? What is the purpose of setting the bandwidth? (Hint: Function of a router) What is the encapsulation currently set to? Step 4 - Remove the bandwidth setting from Serial S0 with the following series of commands: Lab-A# config t Lab-A(config)# int s0 Lab-A(config-if)# no bandwidth Use the show interface s0 command again. What is default bandwidth set to now? Why do you think this is? Change the bandwidth back to 56 Kbits with the following series of commands: Lab-A# config t Lab-A(config)# int s0 Lab-A(config-if)# bandwidth 56 Use the show interface s0 command again to verify that the bandwidth has been changed. Step 5 - Use the show cdp neighbors command and answer the following questions Lab-A# show cdp neighbors What is the device ID of the neighboring router? What is the Local Interface that this device was discovered on? What is the capability of the device? What model platform number is it? What is the Port ID for the neighboring router interface? Step 6 - Check Configuration of the WAN Interface on Router Lab-B Telnet from Router Lab-A to Router Lab-B and use the lab diagram and the show running-config command to answer the following questions (either telnet to the router name or the IP address of the Serial interface): Lab-B# show running-config Which Serial interface is used for the WAN link? What is the IP address of this interface? What is the subnet mask of this interface? Is this interface a DCE or DTE connection? How do you know if it is DCE or DTE? What is the clock rate set to for this interface? What is the bandwidth set for this interface? Step 7 - Examine the WAN cables attached to Router Lab-B and answer the following questions: What interface is the cable attached to on Router Lab-B? What type of physical connector is the Serial port on the router? What type of physical connector is on the other end of the cable? Step 8 - Use the show interface command and answer the following questions: Lab-B# show interface serial 1 What is the status of the interface and the Line protocol? How is the IP address and Subnet mask shown? What is the Maximum Transmission Unit (MTU)? What is the bandwidth set to? What is the encapsulation currently set to? Step 9 - Use the show cdp neighbors command and answer the following questions Lab-B# show cdp neighbours What is the device ID of the neighboring router? What is the Local Interface that this device was discovered on? What is the capability of the device? What model platform number is it? What is the Port ID for the neighboring router interface? Step 10 - Change the WAN Encapsulation on Router Lab-A from HDLC to PPP Connect your workstation to the console port connection on Router Lab-A and use the following commands to change the WAN encapsulation on Router Lab-A Serial Interface 0 and answer the following questions: Lab-A(config)# interface serial 0 Lab-A(config-if)# encapsulation ppp Use the show interface s0 command. What is the status of the interface and the Line protocol now? What does this mean? What was the encapsulation previously set to? What is the encapsulation now set to now? Can you Ping or Telnet from router Lab-A to router Lab-B? Why or why not? Step 11 - Change the WAN Encapsulation on Router Lab-B from HDLC to PPP Connect your workstation to the console port connection on Router Lab-B (since you can no longer telnet to it) and use the following commands to change the WAN encapsulation to on Router Lab-B Serial Interface 1 and answer the following questions: Lab-B# config t Lab-B(config)# interface serial 1 Lab-B(config-if)# encapsulation ppp Use the show interface s1 command. What is the status of the interface and the Line protocol now? What is the encapsulation currently set to now? Can you Ping or Telnet from router Lab-A to router Lab-B? Why or why not?