Table of Contents

Configuring MPLS with the BPX Switch and the 6400/7200/7500 Routers

This chapter provides information for configuring BPX switches and associated label switching controllers along with edge routers for Multiprotocol Label Switching (MPLS) operation.

Procedures are provided for initial configuration of a router and its various interfaces, including ATM and Ethernet interfaces:

For further information regarding the Cisco 6400, 7200, or 7500 series, detailed software configuration information is provided in the Cisco IOS configuration guide and Cisco IOS command reference publications, which are available on the Cisco Documentation CD-ROM.

Introduction

Configuring the MPLS network consists of setting up ATM router/switches for MPLS. This requires configuring the MPLS controller function on the router entity and the controlled (slave) function on the switch entity of each node.

In the example given here for BPX MPLS nodes (BPX 8650 ATM-LSRs):

When MPLS is running in the network, the routing protocol (such as OSPF) determines the paths through the MLPS switch network from every Edge Label Switch Router (LSR) to every IP destination. Based on this routing information, MPLS automatically sets up a Label VC (LVC) along each path by using the Label Distribution Protocol (LDP).

Consider packets arriving at the edge of the MPLS network with a particular destination IP address:

1. Labels are applied to these packets at the Edge LSR.

2. The resulting ATM cells are forwarded along the appropriate LVC path through the network using label swapping at each label switch until the far-end Edge LSR is reached.

3. The far-end Edge LSR removes the label, rebuilds the frame, and forwards the IP packet to its LAN destination.

Equipment and Software Requirements

Configuration Preview

Setting up label switching on a node involves is essentially a three-step process:

1. Configuring BPX switch

2. Setting up edge routers (can include setting up policies, and so on)

3. IP routing (typically OSPF or IS-IS) automatically discovers the network topology

4. MPLS automatically sets up LVCs across the network

Figure 5-1 shows a high-level view of an MPLS network. The packets destined for 204.129.33.127 could be real time video, while the packets destined for 204.133.44.129 could be from data files.

Once IP routing and MPLS have been set up on the nodes as shown in Figure 5-1, (ATM-LSR 1 through ATM-LSR 5, Edge LSR_A, Edge LSR_B, and Edge LSR_C), automatic network discovery is thereby enabled. Then MPLS will automatically set up LVCs across the network. At each ATM LSR (label switch), label swapping is used to transport the cells across the previously set up LVC paths.

("Label swapping" is a name for VCI switching, the underlying capability of an ATM switch.)

At the Edge LSRs, labels are added to incoming IP packets and labels are removed from outgoing packets. Figure 5-1 shows IP packets with host destination 204.129.33.127 transported as labeled ATM cells across LVC 1, and IP packets with host destination 204.133.44.129 transported as labeled ATM cells across LVC 2.

IP addresses shown are for illustrative purposes only and are assumed to be isolated from external networks. Check with your Network Administrator for appropriate IP addresses for your network.

Figure 5-2 is a detailed diagram showing the MPLS label swapping that might take place in the transportation of the IP packets in the form of ATM cells across the network on the LVC1 and LVC2 virtual circuits:

1. An unlabeled IP packet with destination 204.133.44.129 arrives at Edge Label Switching Router (LSR-A).

2. Edge LSR-A checks its label forwarding information base (LFIB) and matches the destination with prefix 204.133.44.0/8.

3. LSR-A converts the AAL5 frame to cells and sends the frame out as a sequence of cells on 1/VCI 50.

4. ATM-LSR-1 (which is a BPX 8650 Label Switch Router) is controlled by a Label Switch Controller (6400, 7200, or 7500 router). The controller has an LFIB that was established by IP routing and MPLS signaling. At the time the LFIB entries were established, the controller used the VC switching information in the LFIB to establish VC connections in the switch. In this case, the incoming cells on interface 2/VCI 50 are switched to outgoing interface 0/VCI 42. The cell-by-cell switching is invisible to the controller, because the traffic is carried only by the switch and does not pass through the controller.

5. Similarly, at ATM-LSR-2, the incoming cells on interface 2/VCI 42 are switched to outgoing interface 0/VCI 90, according to the LFIB.

6. Edge LSR-C receives the incoming cells on incoming interface 1/VCI 90, checks its LFIB, converts the ATM cells back to an AAL5 frame, then to an IP packet, and then sends the outgoing packet onto its LAN destination 204.133.44.129.

Initial Setup of MPLS Switching

This section provides an example of configuring BPX 8650 MPLS label switches (ATM-LSRs) for MPLS switching of IP packets through an ATM network, along with configuration for 6400/7200/7500 routers for use as Label Edge Switch Routers (Edge LSRs) at the edges of the network.

The example in this section describes the configuration of:

The configuration of ATM LSR-3, ATM LSR-4, and ATM LSR-5 is not detailed, but would be performed in a similar manner to that for ATM LSR-1 and ATM LSR-2. Also, the configuration of Edge LSR-B (7500 router) would be similar to that for Edge LSR-A and LSR-C.

The configuration of a BPX 8650 ATM-LSR consists of two parts:

Configuration for BPX Switch Portions of the BPX 8650 ATM-LSRs

The BPX nodes must be set up and configured in the ATM network, including links to other nodes, and so on. Following this, they may be configured for MPLS operation.

To configure the BPX nodes for operation, you set up a virtual switch interface and associated partition by using the cnfrsrc command.

You link the 6400, 7200, or 7500 router to the BPX by using the addshelf command to allow the router's label switch controller function to control the MPLS operation of a node.

You may distribute the resources of the partition between the associated ports. Resources include bandwidth, VPI range, and number of logical connection spaces (LCNs). The VPIs are of local significance, so they do not have to be the same for each port in a node, but it is generally convenient from a tracking standpoint to keep them the same for a given BPX node.

In this example, it is assumed that a single external controller per node is supported, so that the partition chosen is always 1.

Command Syntax Summary for BPX Portion of MPLS Configuration

Syntax for associated commands, cnfrsrc, cnfqbin, addshelf are:

{if you enter "y", to Edit parms?

{accepts defaults if you enter "n" to Edit parms

{If you enter "n" to not accept template values

{If you enter "y" to accept template values.

Configuration for BPX 1 Portion of ATM-LSR-1

To configure the BPX 8650 label switch routers, ATM-LSR-1 and ATM-LSR-2:

Configuration for BPX 2 Portion of ATM-LSR-2

Proceed with configuration as follows:

Configuration for LSC 1 and LSC 2 Portions of the BPX 8650

Before configuring the routers for the label switch (MPLS) controlling function, it is necessary to perform the initial router configuration.

As part of this configuration, it is necessary to enable and configure the ATM Adapter interface as described in "Configuring ATM Interfaces" section.

Then the extended ATM interface can be set up for Label Switching, and the BPX ports configured by the router as extended ATM ports of the router physical ATM interface according to the following procedures for LSC1 and LSC2.

Configuration for LSC1 Portion of ATM-LSR-1

Configuration for LSC2 Portion of ATM-LSR-2

Configuration for Edge Label Switch Routers, LSR-A and LSR-B

Before configuring the routers for the MPLS controlling function, it is necessary to perform the initial router configuration.

As part of this configuration, you must enable and configure the ATM Adapter interface as described in "Configuring ATM Interfaces" section.

Then you can set up the extended ATM interface for MPLS, and the BPX ports configured by the router as extended ATM ports of the router physical ATM interface according to the following procedures for LSR-A and LSR-C.

To configure the 7500 routers performing as label edge routers, use the procedures in the following tables.

Configuration of Cisco 7500 as An Edge Router, Edge LSR-A

Configuration of Cisco 7500 as An Edge Router, Edge LSR-C

MPLS Configures LVCs According to the Routing Protocol

After you have completed the initial configuration procedures for the BPX 8650 and Edge LSRs as described in the previous paragraphs, the routing protocol (such as OSPF) runs and builds routing protocols in each LSC and Edge LSR. The MPLS software in these devices then uses the Tag Distribution Protocol to set up LVCs, including those shown in Figure 5-4.

Testing the MPLS Network Configuration

Preliminary testing of the MPLS network consists of:

Useful LSC Commands

The following are some of the useful LSC (also referred to as TSC) commands for monitoring and troubleshooting an MPLS network:

For a complete description of these LSC commands refer to the related IOS MPLS documentation:

Checking the BPX Extended ATM Interfaces

Use the following procedure as a quick checkout of the tag switching configuration and operation with respect to the BPX switch, for example ATM LSR-1:

The sample output for ATM-LSC-1 (BPX 8650 shelf) is:

---

Note    Check the LSC online documentation for the most current information.

---

Step 2   If there are no interfaces present, first check that card 1 is up,
by using this command on the BPX switch:

and, if the card is not up, in this example BXM in slot 1 of the BPX shelf:

and/or remove the card to get it to reset if necessary.

---

Note    This example assumes that the controller is connected to card 1 on the switch. Substitute a different card number, as applicable.

---

Step 3   Check the trunk status with the following command:

The dsptrks screen for ATM-LSR-1 should show the 1.1, 1.3, and 2.2 MPLS interfaces, with the "Other End" of 1.1 reading "VSI (VSI)". Here's a typical dsptrks screen:

Step 4   Enter the dspnode command.

The resulting screens should show trunk 1.1 (link to LSC on ATM-LSR-1) as type VSI. Here's typical dspnode screen:

Step 5   Enter the dsprsrc command:

The resulting screen should show these settings:

Step 6   Enter the dspqbin command:

The resulting screen should show these settings:

Step 7   If interfaces 1.3 and 2.2 are present, but not enabled, perform the previous debugging steps for interfaces 1.3 and 2.2 instead of 1.1, except for the dspnode command, which does not show anything useful pertaining to ports 1.3 and 2.2.

Step 8   Try a ping on the label switch connections. If the ping doesn't work, but all the label switching and routing configuration looks correct, check that the LSC has found the VSI interfaces correctly by entering the following command at the LSC:

If the interfaces are not shown, recheck the configuration of port 1.1 on the BPX switch as described in the previous steps.

Step 9   If the VSI interfaces are shown, but are down, check whether the LSRs connected to the BPX switch show that the lines are up. If not, check such items as cabling and connections.

Step 10   If the LSCs and BPX switches show the interfaces are up, but the LSC doesn't show this, enter the following command on the LSC:

If the "show tag int" command shows that the interfaces are up, but the ping doesn't work, enter the follow command at the LSC:

The resulting display should show something similar to this:

Step 11   If the interfaces on the display show "xmit" and not "xmit/recv", then the LSC is sending LDP messages, but not getting responses. Enter this command on the neighboring LSRs.

If resulting displays also show "xmit" and not "xmit/recv", then one of two things is likely:

Step 12   Check the VSI configuration on the switch again, for interfaces 1.1, 1.3, and 2.2, paying particular attention to:

---

Note    VSI partitioning and resources must be set up correctly on the interface connected to the LSC, interface 1.1 in this example, as well as interfaces connected to other label switching devices.

---

Basic Router Configuration

This section provides basic configuration information for the Cisco 6400, 7200, or 7500 routers used as the Label Switch Controller for the BPX 8650:

Accessing the Router Command-Line Interface

To configure a router, you must access its command line interface (CLI).

If you will be configuring the router on-site, connect a console terminal (an ASCII terminal or a PC running terminal emulation software) to the console port on the router.

For remote access, connect a modem to the auxiliary port on the router.

Booting the Router for the First Time

Each time you turn on power to the router, it goes through the following boot sequence:

1. The router goes through power-on self-test diagnostics to verify basic operation of the CPU, memory, and interfaces.

2. The system bootstrap software (boot image) executes and searches for a valid Cisco IOS image. The factory-default setting for the configuration register is 0x2102, which indicates that the router should attempt to load a Cisco IOS image from Flash memory.

3. If after five attempts a valid Cisco IOS image is not found in Flash memory, the Cisco router reverts to boot ROM mode (which is used to install or upgrade a Cisco IOS image).

4. If a valid Cisco IOS image is found, then the Cisco router searches for a valid configuration file.

5. If a valid configuration file is not found in NVRAM, the Cisco  router runs the System Configuration Dialog so you can configure it manually. For normal router operation, there must be a valid Cisco IOS image in Flash memory and a configuration file in NVRAM.

The first time you boot the router, you need to configure the router interfaces and then save the configuration to a file in NVRAM. Proceed to the next section, "Configuring the Router for the First Time," for configuration instructions.

Configuring the Router for the First Time

You can configure the Cisco router by using one of the procedures described in this section:

TimeSaver Obtain the correct network addresses from your system administrator or consult your network plan to determine correct addresses before you begin to configure the router.

Use the procedure that best meets the needs of your network configuration and level of experience using Cisco IOS software.

If you use configuration mode or AutoInstall to configure the router and you would like a quick review of the Cisco IOS software, refer to the section "Cisco IOS Software Basics" later in this chapter. Otherwise, proceed to the next section, "Using the System Configuration Dialog."

Using the System Configuration Dialog

If your router does not have a configuration (setup) file and you are not using AutoInstall, the router will automatically start the setup command facility. An interactive dialog called the System Configuration Dialog appears on the console screen. This dialog helps you navigate through the configuration process by prompting you for the configuration information necessary for the Cisco router to operate.

Note   Many prompts in the System Configuration Dialog include default answers, which are included in square brackets following the question. To accept a default answer, press Return; otherwise, enter your response.

This section gives a sample configuration using the System Configuration Dialog. When you are configuring your router, respond as appropriate for your network.

At any time during the System Configuration Dialog, you can request help by entering a question mark (?) at a prompt.

Before proceeding with the System Configuration Dialog, obtain from your system administrator:

To configure the router by using the System Configuration Dialog:

Step 2   Wait about 30 seconds for messages to be displayed, corresponding to the Cisco IOS release and feature set you selected. The screen displays in this section are for reference only and might not exactly reflect the screen displays on your console:

Step 3   Press Return or enter yes to begin the configuration process.

Step 4   When the System Configuration Dialog asks whether you want to view the current interface summary, press Return or enter yes:

Step 5   Configure the global parameters. Here's a typical configuration:

Step 6   Next, you are prompted to enter an enable secret password. There are two types of privileged-level passwords:

The enable password is used when the enable secret password does not exist. For maximum security, be sure the passwords are different. If you enter the same password for both, the Cisco router will accept your entry, but will display a warning message indicating that you should enter a different password.

Step 7   Enter an enable secret password:

Step 8   Enter the enable and virtual terminal passwords:

Step 9   Press Return to accept Simple Network Management Protocol management, or enter no to refuse it:

Step 10   In this example, the Cisco router is configured for AppleTalk, IP, MPLS, and Internetwork Packet Exchange. Configure the appropriate protocols for your router:

---

Note    It is recommended that an MPLS network use either OSPF or IS-IS routing as its routing protocol. EIGRP will also work, but it does not support the useful MPLS feature Traffic Engineering. IGRP and RIP protocols are not recommended.

---

Configuring Port Adapter Interfaces

Here is an overview of the procedure:

1. Make port adapter cable connections and complete basic configuration on the router.

2. Configure the applicable port adapter interfaces on the router, Ethernet, Fast Ethernet, ATM, FDDI, and so on.

3. Configure the router for MPLS operation.

4. Add permanent virtual circuits (PVCs) as applicable.

Preparing to Configure Port Adapter Interfaces

If you want to configure interfaces in a new Cisco 6400, 7200, or 7500 series router, or if you want to change the configuration of an existing interface, be prepared with the information you will need:

The configure command requires privileged-level access to the EXEC command interpreter, which usually requires a password. Contact your system administrator if necessary to obtain EXEC-level access.

Identifying Chassis Slot, Port Adapter Slot, and Interface Port Numbers

You will need to identify chassis slot, port adapter slot, and interface port numbers on the 6400, 7200, or 7500 Series routers for all port adapter interface types.

Physical port addresses specify the actual physical location of each interface port, regardless of the type.

You can identify port adapter interface ports by physically checking the slot/interface port location on the 7200 or 7500 Series routers, or by using the show commands to display information about a specific interface or all interfaces.

Configuring ATM Interfaces

This section provides the procedure for a basic interface configuration.

Press the Return key after each step unless otherwise noted. At any time you can exit the privileged level and return to the user level by entering disable at the prompt as follows:

To perform a basic configuration:

Step 2   At the prompt, enter:

This example is the 1/0 interface of the ATM port adapter in a 7200 series router:

Step 3   If IP routing is enabled on the system, you can assign an IP address and subnet mask to the interface with the ip address configuration subcommand:

Step 4   Add any additional configuration subcommands required to enable routing protocols and set the interface characteristics.

Step 5   Change the shutdown state to UP and enable the interface:

Step 6   Repeat Step 2 through Step 5 to configure additional interfaces as required.

Step 7   When you have completed the configuration, press Ctrl-Z to exit configuration mode.

Step 8   Write the new configuration to nonvolatile memory:

---

Note    If you are going to unattach/reconfigure the ATM interface cable, use the shutdown command prior to this action. After re-attaching the ATM interface cable, use the no shutdown command to bring the ATM interface into an up state.

---

Other Router Interfaces

The router has other interfaces for carrying IP traffic. Refer to the Cisco 7200 or 7500 series router documentation, as applicable.

Checking the Configuration

After configuring the new interface, use:

Using Show Commands to Verify the New Interface Status

This procedure uses show commands to verify that the new interfaces are configured and operating correctly:

Step 2   Display all the current port adapters and their interfaces by using the show controllers command. Verify that the new port adapter appears in the correct slot.

Step 3   Specify one of the new interfaces by using the show interfaces port adapter type slot/interface command.

Step 4   Display the protocols configured for the entire system and specific interfaces with the show protocols command. If necessary, return to configuration mode to add or remove protocol routing on the system or specific interfaces.

Step 5   Display the running configuration file with the show running-config command.

Step 6   Display the configuration stored in NVRAM using the show startup-config command.

Step 7   Verify that the configuration is accurate for the system and each interface.

If the interface is down and you configured it as up, or if the displays indicate that the hardware is not functioning properly, ensure that the network interface is properly connected and terminated. If you still have problems bringing the interface up, contact a service representative for assistance.

Using Show Commands to Display Interface Information

To display information about a specific interface, use the show interfaces command with the interface type and port address in the format show interfaces [type slot/port] for the Cisco router.

Cisco Show Interfaces Command

Here is an example of how the show interfaces [type slot/port] command displays status information (including the physical slot and port address) for the interfaces you specify. (Interfaces are administratively shut down until you enable them.)

When running the show interfaces type slot/port command, use arguments such as the interface type (Ethernet, and so on), slot, and the port number (slot/port) to display information about a specific Ethernet 10BASE-T interface only.

The show version (or show hardware) command displays the configuration of the system hardware (the number of each port adapter type installed), the software version, the names and sources of configuration files, and the boot images. Here's an example of the show version command:

To determine which type of port adapter is installed in your system, use the show diag command. Specific port adapter information is displayed:

Proceed to the "Using the ping Command" section to verify that each interface port is functioning properly.

Using the ping Command

The packet internet groper (ping) command allows you to verify that an interface port is functioning properly and to check the path between a specific port and connected devices at various locations on the network. After you verify that the system has booted successfully and is operational, you can use ping to verify the status of interface ports.

The ping command sends an echo request out to a remote device at an IP address that you specify. After sending a series of signals, the command waits a specified time for the remote device to echo the signals. Each returned signal is displayed as an exclamation point (!) on the console terminal; each signal that is not returned before the specified time-out is displayed as a period (.). A series of exclamation points (!!!!!) indicates a good connection; a series of periods (.....) or the messages [timed out] or [failed] indicate that the connection failed.

Here is a successful ping command to a remote server with the address 1.1.1.10:

If the connection fails, verify that you have the correct IP address for the server and that the server is active (powered on), then repeat the ping command.

Using Configuration Mode

You can configure the 7200 router manually if you prefer not to use AutoInstall or the prompt-driven System Configuration Dialog.

Refer to the section "Cisco IOS Software Basics" later in this chapter for basic information about Cisco IOS software, getting context-sensitive help, and saving configuration changes.

To configure the Cisco 7200 router manually:

Step 2   Power ON the Cisco 7200 router.

Step 3   When you are prompted to enter the initial dialog, enter no to go into the normal operating mode of the Cisco 7200 router:

Step 4   After a few seconds you will see the user EXEC prompt (Router>). By default, the host name is Router, but the prompt will match the current host name. In the following examples, the host name is aries.

Step 5   Enter the enable command to enter enable mode. You can make only configuration changes in enable mode:

The prompt will change to the privileged EXEC (enable) prompt:

Step 6   Enter the configure terminal command at the enable prompt to enter configuration mode:

You can now enter any changes you want to the configuration. You will probably want to perform these tasks:

Refer to the Cisco IOS configuration guide and command reference publications for more information about the commands you can use to configure the 7200 or 7500 series routers.

Step 7   When you finish configuring the router, enter the exit command until you return to the privileged EXEC prompt (7200 router aries#).

Step 8   To save the configuration changes to NVRAM, enter the copy running-config startup-config command at the privileged EXEC prompt:

The Cisco router is now configured and will boot with the configuration you entered.

Cisco IOS Software Basics

The section provides basic information about the Cisco IOS software:

Cisco IOS Modes of Operation

Cisco IOS software provides access to several different command modes. Each command mode provides a different group of related commands.

For security purposes, Cisco IOS software provides two levels of access to commands:

The commands available in user EXEC mode are a subset of the commands available in privileged EXEC mode.

Table 5-1 describes some of the most commonly used modes, how to enter the modes, and the resulting prompts. The prompt helps you identify which mode you are in and, therefore, which commands are available to you.

Almost every configuration command also has a no form. In general, use the no form to disable a feature or function. Use the command without the keyword no to reenable a disabled feature or to enable a feature that is disabled by default.

For example, IP routing is enabled by default. To disable IP routing, enter the no ip routing command and enter ip routing to reenable it. The Cisco IOS software command reference publication provides the complete syntax for the configuration commands and describes what the no form of a command does.

Getting Context-Sensitive Help

In any command mode, you can get a list of available commands by entering a question mark (?).

To obtain a list of commands that begin with a particular character sequence, type in those characters followed immediately by the question mark (?). Do not include a space. This form of help is called word help, because it completes a word for you.

To list keywords or arguments, enter a question mark in place of a keyword or argument. Include a space before the question mark. This form of help is called command syntax help, because it reminds you which keywords or arguments are applicable based on the command, keywords, and arguments you have already entered.

You can also abbreviate commands and keywords by entering just enough characters to make the command unique from other commands. For example, you can abbreviate the show command to sh.

Saving Configuration Changes

Whenever you make changes to the Cisco 7200 router configuration, you must save the changes to memory so they will not be lost if there is a system reload or power outage.

There are two types of configuration files:

To display the current running configuration, enter the show running-config command.

To save the current running configuration to the startup configuration file in NVRAM, enter the copy running-config startup-config command:

To display the startup configuration, enter the show startup-config command.

To write the startup configuration to the running configuration, enter the copy startup-config running-config command.