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Example: Connecting Logical Systems Within the Same Router Using Logical Tunnel Interfaces on MX Series Routers

This example shows how to configure logical tunnel interfaces to connect two logical systems that are configured in a single MX Series 3D Universal Edge Router.

Requirements

The MX Series router chassis must have a DPC, MPC, or MIC installed and in the online state.

Overview

To connect two logical systems, you configure a logical tunnel interface on both logical systems. Then you configure a peer relationship between the logical tunnel interfaces, thus creating a point-to-point connection. Logical tunnel interfaces behave like regular interfaces. You can configure them with Ethernet, Frame Relay, or another encapsulation type. You can also configure routing protocols across them. In effect, the logical tunnel (lt) interfaces connect two logical systems within the same router. The two logical systems do not share routing tables. This means that you can run dynamic routing protocols between different logical systems within the same router.

You must treat each interface like a point-to-point connection because you can only connect one logical tunnel interface to another at any given time. Also, you must select an interface encapsulation type, configure a corresponding protocol family, and set the logical interface unit number of the peering lt interface.

In this example, the logical tunnel interfaces are configured to behave as Ethernet interfaces with the encapsulation ethernet statement. The IS-IS Protocol is enabled on the logical tunnel interfaces with the family iso statement.

When configuring logical tunnel interfaces, note the following:

  • The peering logical interfaces must have the same lt interface name. For example, a logical unit on lt-0/1/0 cannot peer with a logical unit on lt-0/0/10. The FPC (DPC, MPC, or MIC), PIC, and port numbers must match.
  • The peering logical interfaces must be derived from the same module.
  • You can configure only one peer unit for each logical interface. For example, unit 0 cannot peer with both unit 1 and unit 2.

Figure 1 shows the topology used in this example.

Figure 1: Connecting Two Logical Systems

Connecting Two Logical Systems

Configuration

CLI Quick Configuration

To quickly configure this example, copy the following commands, paste them into a text file, remove any line breaks, change any details necessary to match your network configuration, and then copy and paste the commands into the CLI at the [edit] hierarchy level.

set chassis fpc 0 pic 1 tunnel-services bandwidth 1gset logical-systems LS1 interfaces lt-0/1/0 unit 0 description LS1->LS2 set logical-systems LS1 interfaces lt-0/1/0 unit 0 encapsulation ethernet set logical-systems LS1 interfaces lt-0/1/0 unit 0 peer-unit 1 set logical-systems LS1 interfaces lt-0/1/0 unit 0 family inet address 10.0.8.13/30 set logical-systems LS1 interfaces lt-0/1/0 unit 0 family iso set logical-systems LS2 interfaces lt-0/1/0 unit 1 description LS2->LS1 set logical-systems LS2 interfaces lt-0/1/0 unit 1 encapsulation ethernet set logical-systems LS2 interfaces lt-0/1/0 unit 1 peer-unit 0 set logical-systems LS2 interfaces lt-0/1/0 unit 1 family inet address 10.0.8.14/30 set logical-systems LS2 interfaces lt-0/1/0 unit 1 family iso

Step-by-Step Procedure

The following example requires you to navigate various levels in the configuration hierarchy. For information about navigating the CLI, see Using the CLI Editor in Configuration Mode in the CLI User Guide.

To connect logical system interfaces:

  1. Run the show chassis fpc command to verify that the router has a DPC, MPC, or MIC installed and is in the online state.
    user@host> show chassis fpc
                         Temp  CPU Utilization (%)   Memory    Utilization (%)
Slot State            (C)  Total  Interrupt      DRAM (MB) Heap     Buffer
  0  Online            31      4          0       1024       14         21
  1  Empty           
  2  Empty

    This output shows that slot 1 and slot 2 are empty. Slot 0 is online.

  2. Configure FPC slot 0 to support logical tunnel (lt) interfaces.

    [edit]user@host# set chassis fpc 0 pic 1 tunnel-services bandwidth 1g
    This command creates several tunnel interface types, including gr, ip, and lt. For this example, the important one is the logical tunnel (lt) interface.

  3. Commit the configuration.

    [edit]user@host# commit
  4. Run the show interfaces terse command to verify that the router has a logical tunnel (lt) interface.
    user@host> show interfaces terse
    Interface               Admin Link Proto    Local                 Remote
...
gr-0/1/0                up    up  
ip-0/1/0                up    up  
lt-0/1/0                up    up  
...

  5. Configure the logical tunnel interface on Logical System LS1.

    [edit]user@host# set logical-systems LS1 interfaces lt-0/1/0 unit 0 description LS1->LS2 user@host# set logical-systems LS1 interfaces lt-0/1/0 unit 0 encapsulation ethernet user@host# set logical-systems LS1 interfaces lt-0/1/0 unit 0 peer-unit 1 user@host# set logical-systems LS1 interfaces lt-0/1/0 unit 0 family inet address 10.0.8.13/30 user@host# set logical-systems LS1 interfaces lt-0/1/0 unit 0 family iso

  6. Configure the logical tunnel interface on Logical System LS2.

    [edit]user@host# set logical-systems LS2 interfaces lt-0/1/0 unit 1 description LS2->LS1 user@host# set logical-systems LS2 interfaces lt-0/1/0 unit 1 encapsulation ethernet user@host# set logical-systems LS2 interfaces lt-0/1/0 unit 1 peer-unit 0 user@host# set logical-systems LS2 interfaces lt-0/1/0 unit 1 family inet address 10.0.8.14/30 user@host# set logical-systems LS2 interfaces lt-0/1/0 unit 1 family iso

  7. If you are done configuring the device, commit the configuration.

    [edit]user@host# commit

Verification

Confirm that the configuration is working properly.

Verifying That the Logical Systems Are Up

Purpose

Make sure that the interfaces are properly configured.

Action

user@host> show interfaces terse
Interface               Admin Link Proto    Local                 Remote
so-0/0/0                up    down
so-0/0/1                up    down
so-0/0/2                up    down
so-0/0/3                up    down
gr-0/1/0                up    up  
ip-0/1/0                up    up  
lt-0/1/0                up    up  
lt-0/1/0.0              up    up   inet     10.0.8.13/30    
                                   iso     
lt-0/1/0.1              up    up   inet     10.0.8.14/30    
                                   iso  
...

Verifying Connectivity Between the Logical Systems

Purpose

Make sure that the network address appears as directly connected.

Action

user@host> show route logical-system all
logical-system: LS1

inet.0: 2 destinations, 2 routes (2 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

10.0.8.12/30       *[Direct/0] 00:00:34
                    > via lt-0/1/0.0
10.0.8.13/32       *[Local/0] 00:00:34
                      Local via lt-0/1/0.0
-----
 
logical-system: LS2

inet.0: 2 destinations, 2 routes (2 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

10.0.8.12/30       *[Direct/0] 00:00:34
                    > via lt-0/1/0.1
10.0.8.14/32       *[Local/0] 00:00:34
                      Local via lt-0/1/0.1
...
 

Related Documentation

 

Published: 2013-02-22

Download This Guide

Supported Platforms

 

Related Documentation

 

Published: 2013-02-22

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