Networking

Configuring a Nortel ASN to connect to the Internet

Configuring a router is actually quite simple, once you get beyond the cryptic command structures. Fortunately, many routers come with GUI configuration tools. The Nortel ASN router is one such router, and Ron Nutter explains its configuration.


Configuring a router and connecting your company to the Internet has been held as some type of deep dark secret by those who work with routers. Although the router commands can seem like a cryptic language for the newcomer, most of the routers today ship with some type of GUI that should keep you from having to get into the bowels of the router OS. Setting up a router shouldn’t be that difficult and it isn’t, especially when you are setting up a point-to-point link to an ISP.

In this Daily Drill Down, I will show you just how simple it is to set up a router on your network. More specifically, I will show you how to set up a Nortel ASN router.

Our router
For our purposes, we will be working with a Nortel ASN router configured with a dual-port Ethernet card and a dual-port sync module. I will assume that at this point you have installed the Ethernet and sync modules in the router, as well as any additional memory or fast packet cache modules that have been purchased. The last step will be the insertion of the firmware PCMCIA card in the slot on the lower right-hand side of the router.

Although not mentioned in the manual, the firmware card ships with the switch set to read-only. Holding the case, with the Nortel label facing toward you, slide the switch you will find recessed on the top of the card toward the center of the card. You can now insert the card into the router. The router will not boot and be configurable until the card is in place. The exact steps that you will need to take in configuring the router will depend on the ISP you use. I will show what is involved in configuring the router to connect to AT&T Managed Internet Service (MIS).

Setting up the router
Now that the router is assembled, you will need to take the serial cable that ships with the router, connect it to the console port (which looks like a regular DB-9 port on your PC), and connect it to an available port on your PC. Depending on how the serial port is configured on your PC, you may need to use a null modem adapter supplied with the serial router cable that you are using. You might even need a DB-25 to DB-9 adapter if the serial port on your PC is not of the DB-25 variety.

You will want to set up a HyperTerminal session to talk to the router. The HyperTerminal session will need to be set up for 9600 baud, 8 data bits, no parity, 1 stop bit, and no flow control. Take an extra step and save this profile so that you can use it later when talking to the router via the console port without having to re-create the profile.

A good indication that you have the HyperTerminal profile correctly created and that the serial cable between the router and the PC is set up correctly is that you will see a series of testing statements that start with the word Testing as the router powers up and performs some basic tests on the different parts of the router. Once the power up sequence has completed, you should see a screen similar to Figure A.

Figure A
The power up sequence begins with Testing and ends with a login prompt.


At the login prompt, enter Manager (this login ID is case-sensitive) and press [Enter]. Once you have logged in, you should see a message about the new present working directory being set to one and being on the backbone technician interface. At the [1:1]$ prompt, type dinfo and press [Enter]. You should see one volume with a state of Formatted showing. If you see a state of Corrupted (according to Nortel support, they see this happen with about one in every 200 cards that are shipped), you will need to call Nortel support at 800-2LANWAN and request a replacement PCMCIA card. An option that Nortel may be able to provide is sending you an unsupported utility that will allow you to reformat the PCMCIA card and then replace the files on the card.

Installation
We are now ready to start the base installation process. This part of the process will get the Ethernet port on the router up to the point where we can continue the configuration of the router. The router configuration is handled through Nortel’s Site Manager program, which ships with the Router OS. To make sure you have the files that you will need to work with the router, type DIR and press [Enter]. One of the files you will see displayed is Install.bat. At the $ prompt, type install and press [Enter]. The Quick Start procedure will now start. This is where you will need the document sent by the ISP (in our case, AT&T) which lists the IP addresses and subnet masks to be assigned to the serial port (that connects to the CSU/DSU that connects to the T1 that connects to your ISP) and to the Ethernet port connecting to your LAN (or public port) on your firewall. Press [Enter]. The next screen will show you the information that you will need to provide (see Figure B). Press [Enter] to accept the default response of Y (for yes) to continue to the next screen.

Figure B
The defaults for the Quick Start setup are very common configuration entries.


When the Slot Menu For Net Module screen appears (also known as Step 1), you will see a list of modules that the install has found installed in the server. The default response listed at the bottom of the screen should match the slot that the Net module (i.e., the Ethernet card) is in. Look at the back of the router and confirm that the Net module is in the slot listed on the screen. Change the slot number to match the slot the Net module is in, if necessary, and press [Enter] to continue.

The next question (Step 2) will ask which port on the card you want to initially set up for the remainder of the configuration process. (This port will also be your initial connection to the router.) By default, port 1 on the Net module will be used. Press [Enter] to accept the default port and continue with the setup process.

The next question you will answer is what to name the circuit or path for this port within the router. In our case, the default name for the circuit will be E121. There is a method to the madness in the naming convention for the circuit. E stands for an Ethernet connection; the first 1 refers to the router number we are working on.

Nortel numbering
The first router in any stack of Nortel routers will be numbered 1, the next 2, etc. This applies only if you have the routers interconnected and are using Nortel’s Virtual Router Redundancy Protocol (VRRP), which allows multiple routers to appear as one single logical router to your network to minimize service disruption due to router failure or maintenance.

The next number (in our case, 2) refers to the slot number that the Net module is in, and the last number (1, in our case) refers to the number of the port we are using on the Net module. To keep things simple and allow for Nortel to support you more easily, accept the default port name provided and press [Enter] to proceed.

When Step 3 appears on the screen, you will need to enter the IP address and subnet mask that your ISP expects the port to be addressed as. Enter the IP address and press [Enter]. When prompted, enter the subnet mask as specified by the ISP for this address and press [Enter] to continue.

The next question asks if the workstation running the Site Manager configuration program is on the same subnet as the router. Accept the default response of N and press [Enter] to continue.

The next question asks for the type of routing protocol to use on this port. The default option is Routing Information Protocol (RIP). Press [Enter] to accept the default response of 1 for RIP and continue with the initial configuration process.

The next screen you will see will be about configuring RIP and the default route. Since we are using AT&T as the ISP for this Daily Drill Down, you can answer no to this question, as AT&T only uses RIP level 1 on their routes. Press [Enter] to accept the default response of N and proceed with the configuration process.

The next question pertains to the level of RIP to run. Press [Enter] to accept the default of RIP level 1 (unless your ISP has specified otherwise).

The next screen will question you about which SNMP community name you want to assign to the router to restrict the workstations that can manage the router remotely. This can be changed later. Accept the default of N to use public as the community name and continue with the setup process.

The Nortel routers use the TFTP process to update and download files kept in the router. Press [Enter] to accept the default in Step 4 to assign the TFTP volume for this purpose. Press [Enter] to accept the default of N in Step 5 to not enable the FTP service on the router.

FTP
You can enable FTP on the router. This can be done later. We are concerned at this point with getting the router up and running at a basic level.

The question in Step 6 asks if you want to enable Telnet access to the router for doing things like ping tests and DNS resolution testing. Accept the default response of N by pressing [Enter] to continue.

In Step 7, you have the option of enabling the Web server on the ASN router to allow for management via a Web browser. Accept the default of N to not enable the service at this time and press [Enter] to continue.

A Configuration Summary screen will now list the configuration settings you have entered. Review the information on the screen and press [Enter] to continue.

In Step 8, you will be asked to save the information you have entered to a file. Press [Enter] to continue with this process. The default name for this file is Startup.cfg. Press [Enter] to save the information to this file. When the process has finished and you are returned to the $ prompt, type save config config and press [Enter] to save the router configuration to a special startup file that will be automatically read during the router boot process.

To test that this part of the router configuration has been successful, power down the router and then turn the power back on. Once the router has finished booting up, log in using the Manager login name. When you have logged in, type SHOW IP CIRC and press [Enter]. You should see an IP circuit listed for the Ethernet port that you just finished configuring. This indicates that the Ethernet port is ready to talk to a PC running the Site Manager program. You are now ready to finish the remaining part of the basic setup of the router.

Finishing setup with Site Manager
After installing Site Manager, start the program. The first time you bring it up, you will need to give it the IP address of the Ethernet port you configured in the router when you started the initial setup process. Accept the default community string and click OK to continue. You will get a message that indicates that the router configuration has some missing items. This is normal the first time you bring it up and will be resolved as you get into Site Manager. When the Site Manager application is up and running, begin the configuration process by clicking on Tools | Configuration Manager | Dynamic. There are three other options you can go with on configuring the router, but I think you will find that Dynamic will be the easiest to work with since you won’t have to upload/download configuration files to/from the router when you make configuration changes.

When the Configuration Manager screen appears, you will see that XCVR1 will have a white background behind the letters (see Figure C). This indicates that the interface has been configured. The next step is creating the circuit for the sync port that will connect to the CSU/DSU that connects to the T1 from your ISP. Click on Circuits | Add Circuit to begin the configuration process for the sync port. When the Add Circuit screen appears, click on the check box beside COM1. You should now see S141 appear in the Circuit Name field. Like the naming convention used with the Ethernet, S in S141 tells you that you are dealing with a sync port, the first 1 indicates that you are dealing with router number 1, the 4 says the port being configured is in slot 4 of the router, and the last 1 indicates that you are using sync port 1. Click OK to save the circuit configuration.

Figure C
The Configuration Manager screen allows you to add circuits and configure many options.


The next screen will be the WAN Protocols screen. Check the configuration sheet that came from your ISP as to the protocol you need to select. If you have a point-to-point circuit between you and your ISP, you will probably select PPP as the WAN protocol. If you are using a frame relay, you will want to use frame relay as the WAN protocol. Once you have selected the WAN protocol appropriate for your configuration, click OK to continue. When the Select Protocols screen appears, you will need to select the protocols that will be allowed to pass over this connection. Since this will be an IP-only connection to the ISP, you will want to go down the list of protocols and click on the check boxes beside IP and RIP. You may need to enable other options depending on what type of connectivity you have with the ISP. After the protocols have been selected, click OK. When the IP configuration screen appears, you will need to enter the IP address and subnet mask specified by the ISP and then click OK. You will be returned to the Configuration Manager screen. The background behind COM1 should now change from blue to white, indicating that the port has been configured.

Setting the default routes for the router
At a minimum, you will need to set a default route so that your router will know how to send traffic out to the ISP. Click on Protocols | IP | Static Routes to start the process. When the IP Static Routes screen appears, click Add. On the IP Configuration screen, enter 0.0.0.0 in the Destination IP Address and Address Mask fields. Enter the IP address of the router port you will be connecting to (at the ISP end of the connection) in the Next Hop Addr field. A default value of 16 will be in the Preference field. You won’t need to change this field at this point. If you have multiple paths to different default gateways, you can specify a priority for which path to use by altering this number. The first path that is used will be 16; the next path used will be 15, etc. Click OK to save this route. When you are returned to the IP Static Routes screen, you should now see the route you just entered on the screen.

For most ISPs, this will be the last step in setting up the router. With AT&T, since they aren’t using RIP level II, you will also need to enter an additional route that, according to AT&T, will give you an IP classless routing. Click Add to add another route. When the IP Configuration screen appears, enter 12.0.0.0 in the Destination IP Address input field and 255.0.0.0 in the Address Mask field. Enter the IP address of the router port you will be connecting to at the ISP end of the connection in the Next Hop Addr field. Click OK to save the route you just entered. You should now see the route you just entered in the list with the first route that you set up. Click Done to save these routes and update the router configuration.

Conclusion
As you can see, setting up a router isn’t that hard. The best thing you can do is take your time when setting up the router and make sure that you have the information you need from the ISP. Keeping a log of the changes you make to the router and when they were made will be good information to have handy when problems show up and you think the router might be the source of the problem.

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