Rate and give feedback:  Feedback Received. Thank You!

Rate and give feedback: 

X

This document helped resolve my issue

Yes No

Additional Comments

800 characters remaining

May we contact you if necessary?

Name:  

E-mail: 

Enter a valid Email ID

Need product assistance? Contact Juniper Support

Submit

This site is protected by hCaptcha and its Privacy Policy and Terms of Service apply.

English  

English

Example: Configuring IS-IS IPv4 and IPv6 Unicast Topologies

Requirements

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

Overview

This example focuses on IPv4 and IPv6 unicast topologies. The IS-IS interface metrics for the IPv4 topology can be configured independently of the IPv6 metrics. You can also selectively disable interfaces from participating in the IPv6 topology while continuing to participate in the IPv4 topology. This enables you to exercise control over the paths that unicast data takes through a network.

To enable an IPv6 unicast topology for IS-IS, include the ipv6-unicast statement:

To configure a metric for the IPv6 unicast topology, include the ipv6-unicast-metric statement:

To exclude an interface from the IPv6 unicast topologies for IS-IS, include the no-ipv6-unicast statement:

Figure 1 shows the topology used in this example. The black lines indicate link membership in the IPv6 topology. The gray lines indicate membership to the IPv4 topology. Using regular TLVs, it would not be possible to build multiple topologies and run an SPF calculation based on them. The multitopology extensions describe an extension to carry the set of supported protocols in the hello packet. After activating multitopology routing support on a link, the link carries all the topologies that the underlying circuit is able to relay.

Figure 1: IS-IS IPv4 and IPv6 Unicast Topologies

CLI Quick Configuration shows the configuration for all of the devices in Figure 1. The section Step-by-Step Procedure describes the steps on Device R1.

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.

Step-by-Step Procedure

1. Configure the interfaces.
   [edit interfaces]user@R1# set so-1/2/0 unit 0 family inet address 10.0.0.1/30user@R1# set so-1/2/0 unit 0 family isouser@R1# set so-1/2/0 unit 0 family inet6 address 2001:db8:0:5::/64 eui-64user@R1# set so-1/2/1 unit 0 family inet address 10.0.0.13/30user@R1# set so-1/2/1 unit 0 family isouser@R1# set so-1/2/2 unit 0 family inet address 10.0.0.17/30user@R1# set so-1/2/2 unit 0 family isouser@R1# set so-1/2/2 unit 0 family inet6 address 2001:db8:0:1::/64 eui-64user@R1# set lo0 unit 0 family inet address 192.168.0.1/32user@R1# set lo0 unit 0 family iso address 49.0002.0192.0168.0001.00user@R1# set lo0 unit 0 family inet6 address 2001:db8::1/128
2. Enable IS-IS on the interfaces.
   [edit protocols isis]user@R1# set interface so-1/2/0.0user@R1# set interface so-1/2/1.0user@R1# set interface so-1/2/2.0user@R1# set interface lo0.0
3. Enable multitopology routing on the IS-IS interfaces.

   The ipv6-unicast statement enables multitopology IS-IS routing on all interfaces that have family iso and family inet6 configured and are listed at the [edit protocols isis interface] hierarchy level.

   [edit protocols isis]user@R1# set topologies ipv6-unicast
4. Disable IPv6 unicast support on a given interface.

   If you do not want to run multitopology IS-IS routing for IPv6 on a given interface, you can disable multitopology routing by including the no-ipv6-unicast statement in the IS-IS interface configuration.

   [edit protocols isis]user@R1# set interface so-1/2/1.0 no-ipv6-unicast

Results

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

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

Verification

Confirm that the configuration is working properly.

• Checking the Topologies on Neighbors
• Checking the IS-IS SPF Calculations
• Checking the Tcpdump Output

Checking the Topologies on Neighbors

Purpose

Determine what topologies are supported on neighboring IS-IS devices.

Action

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

R2
  Interface: so-1/2/0.0, Level: 3, State: Up, Expires in 24 secs
  Priority: 0, Up/Down transitions: 1, Last transition: 05:28:16 ago
  Circuit type: 3, Speaks: IP, IPv6
  Topologies: Unicast, IPV6-Unicast
  Restart capable: Yes, Adjacency advertisement: Advertise
  IP addresses: 10.0.0.2
  IPv6 addresses: fe80::2a0:a514:0:24c

R5
  Interface: so-1/2/1.0, Level: 3, State: Up, Expires in 21 secs
  Priority: 0, Up/Down transitions: 1, Last transition: 05:27:47 ago
  Circuit type: 3, Speaks: IP, IPv6
  Topologies: Unicast
  Restart capable: Yes, Adjacency advertisement: Advertise
  IP addresses: 10.0.0.14

R3
  Interface: so-1/2/2.0, Level: 3, State: Up, Expires in 22 secs
  Priority: 0, Up/Down transitions: 1, Last transition: 05:27:25 ago
  Circuit type: 3, Speaks: IP, IPv6
  Topologies: Unicast, IPV6-Unicast
  Restart capable: Yes, Adjacency advertisement: Advertise
  IP addresses: 10.0.0.18
  IPv6 addresses: fe80::2a0:a514:0:124c

Meaning

As expected, the adjacency with Device R5 only supports the IPv4 unicast topology, while the adjacencies with Device R2 and Device R3 support both the IPv4 and IPv6 topologies.

Checking the IS-IS SPF Calculations

Purpose

Verify that separate SPF calculations are being run for IPv4 and IPv6.

Action

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

IPV4 Unicast IS-IS level 1 SPF results:
Node             Metric     Interface        NH   Via             SNPA
R6.00        20         so-1/2/1.0      IPV4 R5        
R4.00        20         so-1/2/0.0       IPV4 R2        
R5.00        10         so-1/2/1.0      IPV4 R5        
R3.00        10         so-1/2/2.0      IPV4 R3        
R2.00        10         so-1/2/0.0       IPV4 R2        
R1.00        0
  6 nodes

IPV4 Unicast IS-IS level 2 SPF results:
Node             Metric     Interface        NH   Via             SNPA
R6.00        20         so-1/2/1.0      IPV4 R5        
R4.00        20         so-1/2/0.0       IPV4 R2        
R5.00        10         so-1/2/1.0      IPV4 R5        
R3.00        10         so-1/2/2.0      IPV4 R3        
R2.00        10         so-1/2/0.0       IPV4 R2        
R1.00        0
  6 nodes

IPV6 Unicast IS-IS level 1 SPF results:
Node             Metric     Interface        NH   Via             SNPA
R5.00        40         so-1/2/0.0       IPV6 R2        
R6.00        30         so-1/2/0.0       IPV6 R2        
R4.00        20         so-1/2/0.0       IPV6 R2        
R3.00        10         so-1/2/2.0      IPV6 R3        
R2.00        10         so-1/2/0.0       IPV6 R2        
R1.00        0
  6 nodes

IPV6 Unicast IS-IS level 2 SPF results:
Node             Metric     Interface        NH   Via             SNPA
R5.00        40         so-1/2/0.0       IPV6 R2        
R6.00        30         so-1/2/0.0       IPV6 R2        
R4.00        20         so-1/2/0.0       IPV6 R2        
R3.00        10         so-1/2/2.0      IPV6 R3        
R2.00        10         so-1/2/0.0       IPV6 R2        
R1.00        0
  6 nodes

Meaning

As expected, SPF calculations are being performed for IPv4 and IPv6 topologies.

Checking the Tcpdump Output

Purpose

Verify that the link can be a member of both the IPv4 unicast topology and the IPv6 unicast topology.

Action

[...]

15:52:35.719540  In IS-IS, length 82
        p2p IIH, hlen: 20, v: 1, pdu-v: 1, sys-id-len: 6 (0), max-area: 3 (0)
          source-id: 0192.0168.0002, holding time: 27s, Flags: [Level 1, Level 2]
          circuit-id: 0x01, PDU length: 82
            Point-to-point Adjacency State TLV #240, length: 15
              Adjacency State: Up (0)
              Extended Local circuit-ID: 0x00000054
              Neighbor System-ID: 0192.0168.0001
              Neighbor Extended Local circuit-ID: 0x00000043
            Protocols supported TLV #129, length: 2
              NLPID(s): IPv4 (0xcc), IPv6 (0x8e)
            IPv4 Interface address(es) TLV #132, length: 4
              IPv4 interface address: 10.0.0.2
            IPv6 Interface address(es) TLV #232, length: 16
              IPv6 interface address: fe80::2a0:a514:0:24c
            Area address(es) TLV #1, length: 4
              Area address (length: 3): 49.0002
            Restart Signaling TLV #211, length: 3
              Flags [none], Remaining holding time 0s
            Multi Topology TLV #229, length: 4
              IPv4 unicast Topology (0x000), Flags: [none]
              IPv6 unicast Topology (0x002), Flags: [none]

Meaning

The IS-IS hello (IIH) packet shows that IPv4 and IPv6 are supported. The hello packet lists valid IPv4 and IPv6 addresses, and therefore the routing device can create valid next-hop entries. The supported protocols are listed in the multitopology TLV #229.