Table of Contents

MPLS Edge LSRs Connected Through a PVP

PVP Example: Configuring and Connecting Edge LSRs Within a Cisco 6400
PVP Example: Configuring and Connecting Edge LSRs in Separate Cisco 6400s

MPLS Edge LSRs Connected Through a VPI Range

VPI Range Example: Configuring and Connecting Edge LSRs Within a Cisco 6400
VPI Range Example: Configuring and Connecting Edge LSRs in Separate Cisco 6400s

Basic MPLS VPN Configuration Example

PE1: Cisco 6400 NRP1
PE2: Cisco 6400 NRP2
PE1 and PE2 Connectivity: Cisco 6400 NSP
PE3: Cisco 7200
CE1: Cisco 7500
CE2: Cisco 7200
CE3: Cisco 7500

Split Horizon and RIP Example

Multiprotocol Label Switching

This chapter provides examples, restrictions, and prerequisites for multiprotocol label switching (MPLS) features supported by the Cisco 6400 in Cisco IOS Release 12.2(4)B.

This chapter only contains information that is specific to the Cisco 6400 and supplements the following documentation:

This chapter includes the following sections:

Refer to the "Supported Features" chapter for documentation on additional MPLS features.

Restrictions

While configured as an MPLS Label Switch Controller (LSC), the NRP-2 or NRP-2SV can only support LSC functionality. The NRP-1 can also support network management on the Ethernet interface while configured as an MPLS LSC.

Prerequisites

In order to use the Cisco 6400 as an MPLS device, Cisco express forwarding (CEF) switching must be enabled on each NRP.

Split horizon is disabled by default on ATM interfaces. If you are running RIP in your MPLS VPNs, you must enable split horizon. See the "Split Horizon and RIP Example" section for an example.

MPLS Edge Label Switch Router

The MPLS edge label switch router (Edge LSR) analyzes the Layer 3 header of a packet entering the MPLS network. The Edge LSR then maps the header information into a short fixed-length label and attaches the label to the packet. Inside the MPLS network, the ATM LSRs can forward these packets quickly by only looking at the label. When the packet exits the MPLS network, the Edge LSR removes the label and resumes Layer 3 forwarding of the packet.

Cisco 6400 NRPs can be configured as MPLS Edge LSRs that can be connected across MPLS networks by using permanent virtual paths (PVPs) or a virtual path identifier (VPI) range. The following sections provide simple examples of each scenario.

Note   The Cisco 6400 NRP performs Edge LSR routing in compliance with RFC 1483 (aal5snap). Running any additional access protocols (such as PPP, RBE, or L2TP) on the same NRP is not supported.

The Edge LSR examples do not show the connections to the routers external to the MPLS network, but packets can enter and exit the MPLS network through the FastEthernet (FE) port on the Edge LSR NRP, or through a node line card (NLC) in the same Cisco 6400. The examples also do not show the devices within the MPLS or ATM network.

Note   The recommended method of using an NSP to connect two MPLS Edge LSRs is to configure the NSP as a virtual path (VP) switch. A VP switch configuration is also recommended for an NSP connecting an MPLS Edge LSR to an ATM LSR. To configure the Cisco 6400 NSP as a VP switch, see the "Internal Cross-Connections" section of the "Basic NSP Configuration" chapter of the Cisco 6400 Software Setup Guide .

MPLS Edge LSRs Connected Through a PVP

The PVP configuration through the NSP provides transparent NSP redundancy. The NSP switchover does not preserve label virtual circuits (LVCs) unless they are aggregated into a PVP.

PVP Example: Configuring and Connecting Edge LSRs Within a Cisco 6400

In this example, two NRPs are configured as Edge LSRs in the same Cisco 6400. The Edge LSRs are connected to each other through a PVP through the switch fabric of the Cisco 6400, as shown in Figure 3-1.

Figure 3-1   PVP Connection Between Two Edge LSRs Within a Cisco 6400

The following example shows the configuration for NRP1 in Slot 1:

The following example shows the configuration for NRP2 in Slot 2:

To complete the PVP connection between NRP1 and NRP2 in Figure 1, the NSP must be configured to set the path through the switch fabric. The following example shows the VP-switch configuration for the NSP:

PVP Example: Configuring and Connecting Edge LSRs in Separate Cisco 6400s

In this example, two NRPs are configured as Edge LSRs in the separate Cisco 6400s. The Edge LSRs are connected to each other through a PVP through the MPLS network, as shown in Figure 3-2.

Figure 3-2   PVP Connection Between Two Edge LSRs in Separate Cisco 6400s

The following example shows the configuration for NRP1 in Slot 1 of Cisco 6400 A:

The following example shows the configuration for NRP2 in Slot 1 of Cisco 6400 B:

To complete the PVP connection between NRP1 and NRP2 in Figure 1, the NSPs must be configured to set the path through the switch fabric and node line cards (NLCs).

The following example shows the VP-switch configuration for NSP1 in Cisco 6400 A:

The following example shows the VP-switch configuration for NSP2 in Cisco 6400 B:

MPLS Edge LSRs Connected Through a VPI Range

In addition to providing transparent NSP redundancy, configuring a VPI Range to connect two MPLS Edge LSRs enables you to accommodate a large number of LVCs. For more information on VPI ranges, see the "Configuring a VPI Range" section in the "Configuring Tag Switching" chapter in the ATM Switch Router Software Configuration Guide.

VPI Range Example: Configuring and Connecting Edge LSRs Within a Cisco 6400

In this example, two NRPs are configured as Edge LSRs in the same Cisco 6400. The Edge LSRs are connected to each other through a VPI range through the switch fabric of the Cisco 6400, as shown in Figure 3-3.

Figure 3-3   VPI Range Between Two Edge LSRs Within a Cisco 6400

The following example shows the configuration for NRP1 in Slot 1:

The following example shows the configuration for NRP2 in Slot 2:

To complete the VPI range connection between NRP1 and NRP2 in Figure 1, the NSP must be configured to set the paths through the switch fabric. PVP 0 is used to set up the control channels. The following example shows the VP-switch configuration for the NSP:

Note   This example uses the default control channel PVC 0/32. You can also use a channel within the configured VPI range by using the tag-switching atm control-vc interface configuration command on the NRPs. For example, if you want to use the control channel PVC 7/32, then enter tag-switching atm control-vc 7 32 on both NRP1 and NRP2.

VPI Range Example: Configuring and Connecting Edge LSRs in Separate Cisco 6400s

In this example, two NRPs are configured as Edge LSRs in the separate Cisco 6400s. The Edge LSRs are connected to each other through a VPI range through the MPLS network, as shown in Figure 3-4.

Figure 3-4   VPI Range Between Two NRPs in Different Cisco 6400s

The following example shows the configuration for NRP1 in Slot 1 of Cisco 6400 A:

The following example shows the configuration for NRP2 in Slot 1 of Cisco 6400 B:

To complete the VPI range connection between NRP1 and NRP2 in Figure 1, the NSPs must be configured to set the path through the switch fabric and node line cards (NLCs). PVP 0 is used to set up the control channels.

The following example shows the VP-switch configuration for NSP1 in Cisco 6400 A:

The following example shows the VP-switch configuration for NSP2 in Cisco 6400 B:

Note   This example uses the default control channel PVC 0/32. You can also use a channel within the configured VPI range by using the tag-switching atm control-vc interface configuration command on the NRPs. For example, if you want to use the control channel PVC 7/32, then enter tag-switching atm control-vc 7 32 on both NRP1 and NRP2.

MPLS Virtual Private Networks

For general MPLS VPN configuration tasks, examples, and command references, see the "Multiprotocol Label Switching" chapter in the Cisco IOS Switching Services Configuration Guide.

In addition to these configurations, you must configure the NSP to create paths through the switch fabric of the Cisco 6400. The switch fabric provides connectivity between the NRPs and the external ports on the node line cards (NLCs). For general configuration tasks, examples, and command references for configuring paths through the switch fabric, see the "Configuring Virtual Connections" chapter in the ATM Switch Router Software Configuration Guide.

The examples in this section illustrate the configurations necessary to enable MPLS VPN on a Cisco 6400.

Basic MPLS VPN Configuration Example

This section presents a basic Cisco 6400 MPLS VPN configuration. As shown in Figure 3-5, three customer edge (CE) routers are connected to the service provider backbone through three provider edge (PE) routers. Two of the PE routers are NRPs in the Cisco 6400, while the third PE router is a Cisco 7200. CE1 uses dual homing with PE1 and PE3.

CE1 and CE2 are devices in VPN1, while CE3 is in VPN2. PE1, or NRP1 in the Cisco 6400, handles the CE1 portion of VPN1. PE2, or NRP2 in the Cisco 6400, handles VPN2 as well as the CE2 portion of VPN1.

Figure 3-5   Basic Cisco 6400 MPLS VPN Topology

To enable a Cisco 6400 NRP to participate in a VPN, you must configure the NSP to create paths from the NRP through the Cisco 6400 switch fabric. The switch fabric provides the only connection between the NRP and an external port on a network line card (NLC). The switch fabric also provides the only connection between NRPs in the same Cisco 6400. Figure 3-6 shows a detailed schematic of the configuration used in the topology shown in Figure 3-5.

As shown in the accompanying configurations, you can use routed (in compliance with RFC 1483) PVCs for the CE to PE connections, as long as the CE router is capable of performing routing in compliance with RFC 1483 (aal5snap).

Note   Each NRP in a Cisco 6400 is capable of handling multiple VPNs.

Figure 3-6   Detailed Schematic of the MPLS VPN Configuration Shown in Figure 3-5

PE1: Cisco 6400 NRP1

PE1 in Figure 3-6 is connected to PE3, through VP 42, and CE1, through PVC 35/70. In addition, PE1 and PE2, both NRPs in the same Cisco 6400, are connected to each other through VP40.

The following example shows the complete configuration for PE1 (Cisco 6400 NRP1):

PE2: Cisco 6400 NRP2

PE2 in Figure 3-6 is connected to CE2, through PVC 55/60, and CE3, through PVC 45/50. In addition, PE1 and PE2, both NRPs in the same Cisco 6400, are connected to each other through VP40.

The following example shows the complete configuration for PE2 (Cisco 6400 NRP2):

PE1 and PE2 Connectivity: Cisco 6400 NSP

The following example shows the configuration necessary for the PE Cisco 6400 NSP to create the paths in the switch fabric between the NRPs and the OC3 line cards shown in Figure 3-6.

PE3: Cisco 7200

PE3 in Figure 3-6 is connected to PE1, through VP 42, and CE1, through a packet over SONET (POS) link.

The following example shows the complete configuration for PE3 (Cisco 7200):

CE1: Cisco 7500

CE1 in Figure 3-6 is connected to PE1, through PVC 35/70, and PE3, through a packet over SONET (POS) link.

The following example shows the configuration for CE1 (Cisco 7500):

CE2: Cisco 7200

CE2 in Figure 3-6 is connected to PE2, through PVC 55/60.

The following example shows the configuration for the CE2 (Cisco 7200):

CE3: Cisco 7500

CE3 in Figure 3-6 is connected to PE2, through PVC 45/50.

The following example shows the configuration for CE3 (Cisco 7500):

Split Horizon and RIP Example

Note   Split horizon is disabled by default on ATM interfaces. If you are running RIP in your VPNs, you must enable split horizon.

The following example shows a typical configuration for an ATM subinterface on an NRP:

Posted: Thu Nov 6 14:50:52 PST 2003
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