> | Lab 7.3.3 AUX dial-up - Overview Estimated time: 30 min. Objectives: To understand both "in-band" and "out-of-band" router management techniques To compare Synchronous serial Interfaces with Asynchronous serial interfaces To learn the requirements for using a dial-up link with a modem to configure a router To become familiar with the use of the router AUX port for out-of-band management Use Config Maker to create a dial-up Asynchronous WAN link Background: Wide Area Network Scenario This lab focuses "out-of-band" router management using the AUX port on the router and a modem. You can configure and monitor routers and other networking equipment using both in-band and out-of-band techniques. For example, let's say Router Lab-A is in Anaheim, CA. and Lab-B is in Boise, ID. They are connected via a wide area link such as T1 Frame Relay, PRI ISDN or Point-to-Point over T1. Regardless of which you use , your WAN link has a the bandwidth or "speed" of a T1 (1.544 Mbps). You are a Network Administrator in Anaheim and wish to make some configuration changes or check the status for the Lan-B router in Boise. In-Band Network Management If you are attached to the console of router Lab-A and telnet to Router Lab-B across the wide area link, your connection to router Lab-B is considered in-bandwidth or "in-band" since you are using the same WAN link that the data travels on to manage the Lab-B router. If the WAN link goes down or there is a problem with the configuration of the Lab-B router that contributes to the down WAN link, you cannot get to the Lab-B router to monitor or change its configuration since the WAN link is down. In-band management is very common and is preferred if the WAN link is up. Out-of Band Network Management If the Wan link is down you need a "back-door" or an "out-of-band" method to get to the router and check it out to help troubleshoot the problem. This can be provided by redundant Synchronous WAN serial links to other interfaces on the router. They can be the same as the existing high speed WAN link or can be slower such as BRI ISDN or a perhaps a synchronous 56kbps digital data circuit. You can also get to the router by use of its Asynchronous serial ports. Most routers have 2 Asynchronous ports in order to manage the router "out-of-band"; the Console port and the AUX or Auxiliary port. The use of the Asynchronous console port or the AUX port is considered "out-of-band" management. The Console port vs. The AUX port The primary method of configuring routers with these labs has been with the console port. With the console port, your workstation is directly attached to the router with a special rollover cable and bypasses any other interfaces on the router. The console port is normally set to run at 9600 bps (8 data bits, no parity and 2 stop bits or 8-N-2) and does not support hardware flow control. The AUX port requires a modem be attached and allows you to dial into the router from home or any other location. The AUX port can run at the same speed as the fastest modems up to 56kbps and supports hardware flow control. The Console and AUX ports normally use RS-232 serial DB25 connectors (converted to RJ45). Synchronous vs Asynchronous Serial Interfaces Nearly all Wide Area Network links (WAN) links used in Internetworking are "serial" meaning they transmit bits one after another in a series down the wire or fiber cable. They are not the same as the Asynchronous serial connection ports found on the back of most PCs and those used with modems. The console connection from a workstation to the console port on the router is an Asynchronous connection which uses start and stop bits to separate the data bits in the stream. The bit rate on the Asynchronous router console port is set to 9600 bits per second (bps). Asynchronous serial connections are commonly used with short distance connections for terminals (to routers and switches) or for dial-in modem connections which are limited to 56kbps (Kilobits per second or 56 thousand bits per second). A modem can be connected to the AUX port on the router to allow you to dial in Asynchronously and diagnose problems. With this lab you will practice setting up a modem with the router and dialing in from another location to configure it remotely. Note that the AUX port can also be use for Dial-on Demand routing in case the main WAN serial link is down. Tools / Preparation: Prior to starting the lab, the teacher or lab assistant should have a router available and preferably two phone lines into the router that can function with an analog phone connection. (Some phone switches will not work for this lab). If a connection can be made to the phone jack and have you a dial tone then one line will work if the lab can be done from home or another location. This is a hands-on lab and assumes that the phone lines area available for dial in to the router. If phone lines are not available it is still worthwhile to work through the lab and do those portions that are possible. If a phone line is not available it may be possible to simulate this lab with a modem eliminator between the COM port of the PC dialing in and the Router's AUX port. NOTE: You can use ConfigMaker to set up a dial in port or an Asynchronous WAN backup port to simulate this lab. The following is a list of resources required: Cisco router with AUX port (Note: Some routers do not have an AUX port) Standard Asynchronous analog Modem (USR 56K or similar) Rollover cable with DB25 modem connector and RJ45 router connector Phone cable from modem to phone jack 2 Direct inward dial-up analog phone lines (preferably) Router Manuals and modem manuals Remote PC with modem to dial in to the router Workstation with HyperTerminal and a console connection Web Site Resources: Terms and acronyms IP routing protocol IOS command summary Introduction to WAN technologies Cisco ConfigMaker information and download Step 1 - Prepare the Router Configuration for AUX Dial-in Verify that you have a router with an AUX port. Look at the back of the router and check to see that there is an AUX port next to the console port. Some routers such as the 1600 Series do not have an AUX port. Provide password security for dial-in to the AUX port. Connect to the router with a workstation using the console port and HyperTerminal. Set a password for the AUX port as follows: Router# Config t Router(config)# line aux 0 Router(config-line)# password cisco Router(config-line)# login Discover the modem automatically. The Cisco IOS software contains a database of modem capabilities for most modems. You can configure a router to automatically attempt to discover what kind of modem is connected to the line and then to configure that modem. To automatically discover which of the supported modem strings properly initializes your modem and then initialize the modem, enter: Router(config-line)# modem autoconfigure discovery Router(config-line)# modem dialin Set the router port transmission speed (try not to use the baud command if you do not need to, it can cause problems with the router). Enter the following command to set the speed Router(config-line)# speed 38400 Enter the following command to hang up the modem automatically Router(config-line)# autohangup Verify that Hardware flow control is used with Data Carrier Detect (DCD) and Data Terminal Ready (DTR) operations. Enter the following command set flow control Router(config-line)# flowcontrol hardware Configure the line Asynchronous data transmission parameters to 8 data bits, No Parity and 2 Stop bits (8, None and 2 or 8-N-2) Enter the following command to set the number of data bits to 8 Router(config-line)# databits 8 Enter the following command to set the parity to None Router(config-line)# parity none Enter the following command to set the number of data bits to 8 Router(config-line)# stopbits 2 Check the configuration of the AUX port with the show running-config command. The output from the command should show the following port characteristics: line aux 0 password cisco login autohangup flowcontrol hardware Copy the running configuration to the startup configuration to save the AUX port configuration commands you have entered. Router# copy run start Plug the rollover cable RJ45 connector into the AUX port on the back of the router Step 2 - Prepare the Workstation used for Dial-in Review the workstation's 'HyperTerminal' configuration. Click on Start, Programs, Accessories, and then HyperTerminal. Right Click on the icon that is defined for AUX access to the Cisco Router and then click Properties. If one does not exist you can create it using the settings shown in the answers to the worksheet. On the Properties screen, click the Phone Number Tab and then click the on the Configure button. Fill in the following table with the information indicated. Configure the workstation modem (internal or external) to match the transmission settings (speed, Data bits, Parity, Stop bits and Flow Control) for the router AUX port. Fill in the following table with the settings and values you used:
> Configuration Option | Current Setting(s)
> COM Port | Modem Driver Name
> Bits per second (baud) | 34800
> Data bits | 8
> Parity bits | None
> Stop bits | 2
> Flow control | Hardware
Step 3 - Dial-in to the router Using the phone number of the line to the router or a modem eliminator (null modem) cable connected to the router. You should get a prompt and be able to configure it remotely. Step 4 - Use ConfigMaker to create a dial-in Asynchronous WAN link Start ConfigMaker and select a Cisco 2501 router. Select a Dial-in PC with Modem for dial-in and add an Async link between them. Double click on the router to see the configuration generated.