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play_arrow Overview
- play_arrow Introduction to IS-IS
play_arrow Configuring IS-IS
play_arrow Monitoring and Troubleshooting Network Issues
- play_arrow Monitoring Networks
- play_arrow Troubleshooting Network Issues
- play_arrow Troubleshooting IS-IS
play_arrow Configuration Statements and Operational Commands
- Junos CLI Reference Overview

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English

Example: Advertising Label-Switched Paths into IS-IS

date_range 24-Nov-23

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This example shows how to advertise label-switched paths (LSPs) into IS-IS as point-to-point links (sometimes referred to as forwarding adjacencies) so that the LSPs can be used in SPF calculations. The advertisement contains a local address (the from address of the LSP), a remote address (the to address of the LSP), and a metric.

Requirements

No special configuration beyond device initialization is required before configuring this example.

Overview

Figure 1 shows the topology used in this example.

Figure 1: IS-IS Advertising a Label-Switched Path Topology

The example shows how to configure the LSP from Device E to Device D and then advertise this path through IS-IS. The configuration is verified by performing a traceroute operation from Device A to Device D and making sure that the LSP is used for forwarding.

CLI Quick Configuration shows the configuration for all of the devices in Figure 1. The section #configuration442__isis-lsp-advertise-step-by-step describes the steps on Device E.

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.

Device A

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set interfaces fe-1/2/0 unit 0 family inet address 10.0.0.1/30
set interfaces fe-1/2/0 unit 0 family iso
set interfaces fe-1/2/0 unit 0 family mpls
set interfaces fe-1/2/1 unit 0 family inet address 10.0.0.5/30
set interfaces fe-1/2/1 unit 0 family iso
set interfaces lo0 unit 0 family inet address 192.168.0.1/32
set interfaces lo0 unit 0 family iso address 49.0002.0192.0168.0001.00
set protocols rsvp interface lo0.0
set protocols rsvp interface fe-1/2/0.0
set protocols mpls interface fe-1/2/0.0
set protocols bgp group int type internal
set protocols bgp group int local-address 192.168.0.1
set protocols bgp group int neighbor 192.168.0.6
set protocols bgp group int neighbor 192.168.0.5
set protocols bgp group int neighbor 192.168.0.4
set protocols isis interface fe-1/2/0.0 level 1 disable
set protocols isis interface fe-1/2/0.0 level 2 metric 10
set protocols isis interface fe-1/2/0.5 level 2 metric 10
set protocols isis interface fe-1/2/0.5 level 1 disable
set protocols isis interface lo0.0
set routing-options router-id 192.168.0.1
set routing-options autonomous-system 1

Device B

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set interfaces fe-1/2/0 unit 0 family inet address 10.0.0.6/30
set interfaces fe-1/2/0 unit 0 family iso
set interfaces fe-1/2/1 unit 0 family inet address 10.0.0.9/30
set interfaces fe-1/2/1 unit 0 family iso
set interfaces lo0 unit 0 family inet address 192.168.0.2/32
set interfaces lo0 unit 0 family iso address 49.0002.0192.0168.0002.00
set protocols isis interface fe-1/2/0.0 level 1 disable
set protocols isis interface fe-1/2/1.0 level 2 metric 10
set protocols isis interface fe-1/2/1.0 level 1 disable
set protocols isis interface lo0.0
set routing-options router-id 192.168.0.2

Device C

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set interfaces fe-1/2/0 unit 0 family inet address 10.0.0.10/30
set interfaces fe-1/2/0 unit 0 family iso
set interfaces fe-1/2/1 unit 0 family inet address 10.0.0.13/30
set interfaces fe-1/2/1 unit 0 family iso
set interfaces lo0 unit 0 family inet address 192.168.0.3/32
set interfaces lo0 unit 0 family iso address 49.0002.0192.0168.0003.00
set protocols isis interface fe-1/2/0.0 level 1 disable
set protocols isis interface fe-1/2/1.0 level 1 disable
set protocols isis interface fe-1/2/1.0 level 2 metric 10
set protocols isis interface lo0.0
set routing-options router-id 192.168.0.3

Device D

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set interfaces fe-1/2/0 unit 0 family inet address 10.0.0.14/30
set interfaces fe-1/2/0 unit 0 family iso
set interfaces fe-1/2/1 unit 0 family inet address 10.0.0.22/30
set interfaces fe-1/2/1 unit 0 family iso
set interfaces fe-1/2/1 unit 0 family mpls
set interfaces lo0 unit 0 family inet address 192.168.0.4/32
set interfaces lo0 unit 0 family iso address 49.0002.0192.0168.0004.00
set protocols rsvp interface lo0.0
set protocols rsvp interface fe-1/2/1.0
set protocols mpls label-switched-path E-D to 192.168.0.5
set protocols mpls interface fe-1/2/1.0
set protocols bgp group int type internal
set protocols bgp group int local-address 192.168.0.4
set protocols bgp group int neighbor 192.168.0.5
set protocols bgp group int neighbor 192.168.0.1
set protocols bgp group int neighbor 192.168.0.6
set protocols isis interface fe-1/2/0.14 level 1 disable
set protocols isis interface fe-1/2/1.0 level 1 disable
set protocols isis interface lo0.0
set protocols isis label-switched-path E-D level 2
set routing-options router-id 192.168.0.4
set routing-options autonomous-system 1

Device E

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set interfaces fe-1/2/0 unit 0 family inet address 10.0.0.2/30
set interfaces fe-1/2/0 unit 0 family iso
set interfaces fe-1/2/0 unit 0 family mpls
set interfaces fe-1/2/1 unit 0 family inet address 10.0.0.17/30
set interfaces fe-1/2/1 unit 0 family iso
set interfaces fe-1/2/1 unit 0 family mpls
set interfaces lo0 unit 0 family inet address 192.168.0.5/32
set interfaces lo0 unit 0 family iso address 49.0002.0192.0168.0005.00
set protocols rsvp interface lo0.0
set protocols rsvp interface fe-1/2/0.0
set protocols rsvp interface fe-1/2/1.0
set protocols mpls label-switched-path E-D to 192.168.0.4
set protocols mpls interface fe-1/2/0.0
set protocols mpls interface fe-1/2/1.0
set protocols bgp group int type internal
set protocols bgp group int local-address 192.168.0.5
set protocols bgp group int neighbor 192.168.0.6
set protocols bgp group int neighbor 192.168.0.1
set protocols bgp group int neighbor 192.168.0.4
set protocols isis interface fe-1/2/0.0 level 1 disable
set protocols isis interface fe-1/2/1.0 level 1 disable
set protocols isis interface fe-1/2/1.0 level 2 metric 20
set protocols isis interface lo0.0
set protocols isis label-switched-path E-D level 2 metric 15
set routing-options router-id 192.168.0.5
set routing-options autonomous-system 1

Device F

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set interfaces fe-1/2/0 unit 0 family inet address 10.0.0.18/30
set interfaces fe-1/2/0 unit 0 family iso
set interfaces fe-1/2/0 unit 0 family mpls
set interfaces fe-1/2/1 unit 0 family inet address 10.0.0.21/30
set interfaces fe-1/2/1 unit 0 family iso
set interfaces fe-1/2/1 unit 0 family mpls
set interfaces lo0 unit 0 family inet address 192.168.0.6/32
set interfaces lo0 unit 0 family iso address 49.0002.0192.0168.0006.00
set protocols rsvp interface lo0.0
set protocols rsvp interface fe-1/2/0.0
set protocols rsvp interface fe-1/2/1.0
set protocols mpls interface fe-1/2/0.0
set protocols mpls interface fe-1/2/1.0
set protocols bgp group int type internal
set protocols bgp group int local-address 192.168.0.6
set protocols bgp group int neighbor 192.168.0.1
set protocols bgp group int neighbor 192.168.0.5
set protocols bgp group int neighbor 192.168.0.4
set protocols isis interface fe-1/2/0.0 level 1 disable
set protocols isis interface fe-1/2/1.0 level 2 metric 10
set protocols isis interface fe-1/2/1.0 level 1 disable
set protocols isis interface lo0.0
set routing-options router-id 192.168.0.6
set routing-options autonomous-system 1

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 advertise LSPs into IS-IS:

Configure the interfaces.

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[edit interfaces]
user@E# set fe-1/2/0 unit 0 family inet address 10.0.0.2/30
user@E# set fe-1/2/0 unit 0 family iso
user@E# set fe-1/2/0 unit 0 family mpls
user@E# set fe-1/2/1 unit 0 family inet address 10.0.0.17/30
user@E# set fe-1/2/1 unit 0 family iso
user@E# set fe-1/2/1 unit 0 family mpls
user@E# set lo0 unit 0 family inet address 192.168.0.5/32
user@E# set lo0 unit 0 family iso address 49.0002.0192.0168.0005.00

Enable a signaling protocol on the interfaces.

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[edit protocols rsvp]
user@E# set interface lo0.0
user@E# set interface fe-1/2/0.0
user@E# set interface fe-1/2/1.0

Enable MPLS on the interfaces.

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[edit protocols mpls]
user@E# set interface fe-1/2/0.0
user@E# set interface fe-1/2/1.0

Configure the LSP.

Make sure that you configure the reverse LSP on the endpoint, in this case on Device D.
```
[edit protocols mpls]
user@E# set label-switched-path E-D to 192.168.0.4
```

Configure internal BGP (IBGP) peering among the devices that must run MPLS.

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[edit protocols bgp group int]
user@E# set type internal
user@E# set local-address 192.168.0.5
user@E# set neighbor 192.168.0.6
user@E# set neighbor 192.168.0.1
user@E# set neighbor 192.168.0.4

Enable IS-IS on the interfaces, and set the link metric.

IS-IS Level 1 and Level 2 are enabled when you include the interface at [edit protocols isis]. By disabling Level 1, you are in effect creating a Level 2 IS-IS interface.
```
[edit protocols isis]
user@E# set interface fe-1/2/0.0 level 1 disable
user@E# set interface fe-1/2/1.0 level 1 disable
user@E# set interface fe-1/2/1.0 level 2 metric 20
user@E# set interface lo0.0
```
Advertise the LSP through IS-IS.

Make sure that you advertise the LSP on the endpoint, in this case on Device D.
```
[edit protocols isis]
user@E# set label-switched-path E-D level 2 metric 15
```

Configure the router ID and the autonomous system (AS) number.

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[edit routing-options]
user@E# set router-id 192.168.0.5
user@E# set autonomous-system 1

Results

From configuration mode, confirm your configuration by entering the show interfaces, show protocols, and show routing-options commands. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.

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user@E# show interfaces
fe-1/2/0 {
    unit 0 {
        family inet {
            address 10.0.0.2/30;
        }
        family iso;
        family mpls;
    }
}
fe-1/2/1 {
    unit 0 {
        family inet {
            address 10.0.0.17/30;
        }
        family iso;
        family mpls;
    }
}
lo0 {
    unit 0 {
        family inet {
            address 192.168.0.5/32;
        }
        family iso {
            address 49.0002.0192.0168.0005.00;
        }
    }
}

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user@E# show protocols
rsvp {
    interface lo0.0;
    interface fe-1/2/0.0;
    interface fe-1/2/1.0;
}
mpls {
    label-switched-path E-D {
        to 192.168.0.4;
    }
    interface fe-1/2/0.0;
    interface fe-1/2/1.0;
}
bgp {
    group int {
        type internal;
        local-address 192.168.0.5;
        neighbor 192.168.0.6;
        neighbor 192.168.0.1;
        neighbor 192.168.0.4;
    }
}
isis {
    interface fe-1/2/0.0 {
        level 1 disable;
    }
    interface fe-1/2/1.0 {
        level 1 disable;
        level 2 metric 20;
    }
    interface lo0.0;
    label-switched-path E-D {
        level 2 metric 15;
    }
}

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user@E# show routing-options
router-id 192.168.0.5;
autonomous-system 1;

If you are done configuring the device, enter commit from configuration mode.

Verification

Confirm that the configuration is working properly.

Verifying the IS-IS Neighbor
Checking the IS-IS SPF Calculations
Checking the Forwarding Path

Verifying the IS-IS Neighbor

Purpose
Action
Meaning

Purpose

Verify that another neighbor is listed and is reachable over the LSP. The interface field indicates the name of the LSP.

Action

From operational mode, enter the show isis adjacency detail command.

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user@E> show isis adjacency detail
D
  Interface: E-D, Level: 2, State: One-way, Expires in 0 secs
  Priority: 0, Up/Down transitions: 1, Last transition: 1d 00:34:58 ago
  Circuit type: 3, Speaks: IP
  Topologies: Unicast
  Restart capable: No, Adjacency advertisement: Advertise
  IP addresses: 192.168.0.4

F
  Interface: fe-1/2/1.0, Level: 2, State: Up, Expires in 7 secs
  Priority: 64, Up/Down transitions: 1, Last transition: 1d 01:16:22 ago
  Circuit type: 2, Speaks: IP, IPv6, MAC address: 0:5:85:8f:c8:bd
  Topologies: Unicast
  Restart capable: Yes, Adjacency advertisement: Advertise
  LAN id: F.02, IP addresses: 10.0.0.18

A
  Interface: fe-1/2/0.0, Level: 2, State: Up, Expires in 20 secs
  Priority: 64, Up/Down transitions: 1, Last transition: 1d 01:17:20 ago
  Circuit type: 2, Speaks: IP, IPv6, MAC address: 0:5:85:8f:c8:bc
  Topologies: Unicast
  Restart capable: Yes, Adjacency advertisement: Advertise
  LAN id: E.02, IP addresses: 10.0.0.1

Meaning

As expected, Interface: E-D is shown in the output, and the state is shown as One-way.

Checking the IS-IS SPF Calculations

Purpose
Action
Meaning

Purpose

Verify that the LSP is being used in the SPF calculations.

Action

From operational mode, enter the show isis spf brief command.

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user@E> show isis spf brief

 IS-IS level 1 SPF results:
Node             Metric     Interface        NH   Via             SNPA
E.00         0
  1 nodes

 IS-IS level 2 SPF results:
Node             Metric     Interface        NH   Via             SNPA
C.02         30         fe-1/2/0.0       IPV4 A           0:5:85:8f:c8:bc
C.00         25         fe-1/2/1.0      LSP  E-D           
D.03         25         fe-1/2/1.0      LSP  E-D           
D.02         25         fe-1/2/1.0      LSP  E-D           
F.00         20         fe-1/2/1.0      IPV4 F           0:5:85:8f:c8:bd
B.00         20         fe-1/2/0.0       IPV4 A           0:5:85:8f:c8:bc
B.02         20         fe-1/2/0.0       IPV4 A           0:5:85:8f:c8:bc
D.00         15         fe-1/2/1.0      LSP  E-D           
A.00         10         fe-1/2/0.0       IPV4 A           0:5:85:8f:c8:bc
E.02         10
E.00         0
  11 nodes

Meaning

As expected, the SPF results include the LSP, E-D.

Checking the Forwarding Path

Purpose
Action
Meaning

Purpose

Verify that a traceroute operation from Device A to Device D uses the LSP.

Action

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user@A> traceroute 192.168.0.4
traceroute to 192.168.0.4 (192.168.0.4), 30 hops max, 40 byte packets
 1  10.0.0.2 (10.0.0.2)  1.092 ms  1.034 ms  1.174 ms
 2  10.0.0.18 (10.0.0.18)  1.435 ms  2.062 ms  2.232 ms
     MPLS Label=299792 CoS=0 TTL=1 S=1
 3  bb04-cclab-lo0.spglab.juniper.net (192.168.0.4)  2.286 ms  1.432 ms  1.354 ms

Meaning

The output shows that the LSP is used.

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IS-IS User Guide

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Example: Advertising Label-Switched Paths into IS-IS

Requirements

Overview

Configuration

Procedure

CLI Quick Configuration

Step-by-Step Procedure

Results

Verification

Verifying the IS-IS Neighbor

Purpose

Action

Meaning

Checking the IS-IS SPF Calculations

Purpose

Action

Meaning

Checking the Forwarding Path

Purpose

Action

Meaning

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IS-IS User Guide

ON THIS PAGE

Example: Advertising Label-Switched Paths into IS-IS

Requirements

Overview

Configuration

Procedure

CLI Quick Configuration

Step-by-Step Procedure

Results

Verification

Verifying the IS-IS Neighbor

Purpose

Action

Meaning

Checking the IS-IS SPF Calculations

Purpose

Action

Meaning

Checking the Forwarding Path

Purpose

Action

Meaning

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