Example for Configuring IS-IS DIS Election

This section describes how to configure the IS-IS DIS election, including configuring basic IS-IS functions and configuring the DIS priority on each device.

Networking Requirements

In Figure 1:

  • Device A, Device B, Device C, and Device D run IS-IS for IP interworking.

  • Device A, Device B, Device C, and Device D belong to Area 10, and the network type is broadcast (Ethernet in this case).

  • Device A and Device B are Level-1-2 devices; Device C is a Level-1 device; Device D is a Level-2 device.

  • The DIS priority of the interface on Device A is 100.

  • It is required to change the DIS priority so that Device A functions as a Level-1-2 DIS (DR).

Figure 1 Configuring IS-IS DIS election

Device Name

Interface

IP Address

Device A

GE0/1/0

10.1.1.1/24

Device B

GE0/1/0

10.1.1.2/24

Device C

GE0/1/0

10.1.1.3/24

Device D

GE0/1/0

10.1.1.4/24

Configuration Roadmap

The configuration roadmap is as follows:

  1. Enable IS-IS and specify the NET on each router for interworking.

  2. Check information about the IS-IS interfaces on routers with the default priority.

  3. Configure the DIS priority of the interface on each router.

Data Preparation

To complete the configuration, you need the following data:

  • Area addresses of the four routers

  • Levels of the four routers

  • DIS priority of the interface on Device A

Procedure

  1. Configure an IPv4 address for each interface. For configuration details, see Configuration Files in this section.
  2. Display the MAC address of the GE interface on each router. When the DIS priority of each interface is the same, the router whose interface has the largest MAC address is elected as the DIS.

    # Display the MAC address of Gigabit Ethernet 0/1/0 on Device A.

    [~DeviceA] display arp interface gigabitethernet 0/1/0
ARP timeout:1200s
IP ADDRESS      MAC ADDRESS     EXPIRE(M) TYPE        INTERFACE   VPN-INSTANCE
                                          VLAN/CEVLAN PVC
------------------------------------------------------------------------------
10.1.1.1        00e0-fc10-afec            I           GE0/1/0
------------------------------------------------------------------------------
Total:1         Dynamic:0       Static:0    Interface:1    Remote:0
Redirect:0

    # Display the MAC address of Gigabit Ethernet 0/1/0 on Device B.

    [~DeviceB] display arp interface gigabitethernet 0/1/0
ARP timeout:1200s
IP ADDRESS      MAC ADDRESS     EXPIRE(M) TYPE        INTERFACE   VPN-INSTANCE
                                          VLAN/CEVLAN PVC
------------------------------------------------------------------------------
10.1.1.2        00e0-fccd-acdf            I           GE0/1/0
------------------------------------------------------------------------------
Total:1         Dynamic:0       Static:0    Interface:1    Remote:0
Redirect:0

    # Display the MAC address of Gigabit Ethernet 0/1/0 on Device C.

    [~DeviceC] display arp interface gigabitethernet 0/1/0
ARP timeout:1200s
IP ADDRESS      MAC ADDRESS     EXPIRE(M) TYPE        INTERFACE   VPN-INSTANCE
                                          VLAN/CEVLAN PVC
------------------------------------------------------------------------------
10.1.1.3        00e0-fc50-25fe            I           GE0/1/0
------------------------------------------------------------------------------
Total:1         Dynamic:0       Static:0    Interface:1    Remote:0
Redirect:0

    # Display the MAC address of Gigabit Ethernet 0/1/0 on Device D.

    [~DeviceD] display arp interface gigabitethernet 0/1/0
ARP timeout:1200s
IP ADDRESS      MAC ADDRESS     EXPIRE(M) TYPE        INTERFACE   VPN-INSTANCE
                                          VLAN/CEVLAN PVC
------------------------------------------------------------------------------
10.1.1.4        00e0-fcf0-23ed            I           GE0/1/0
------------------------------------------------------------------------------
Total:1         Dynamic:0       Static:0    Interface:1    Remote:0
Redirect:0

  3. Enable IS-IS.

    # Configure Device A.

    [~DeviceA] isis 1
[*DeviceA-isis-1] network-entity 10.0000.0000.0001.00
[*DeviceA-isis-1] quit
[*DeviceA] interface gigabitethernet 0/1/0
[*DeviceA-GigabitEthernet0/1/0] isis enable 1
[*DeviceA-GigabitEthernet0/1/0] commit
[~DeviceA-GigabitEthernet0/1/0] quit

    # Configure Device B.

    [~DeviceB] isis 1
[*DeviceB-isis-1] network-entity 10.0000.0000.0002.00
[*DeviceB-isis-1] quit
[*DeviceB] interface gigabitethernet 0/1/0
[*DeviceB-GigabitEthernet0/1/0] isis enable 1
[*DeviceB-GigabitEthernet0/1/0] commit
[~DeviceB-GigabitEthernet0/1/0] quit

    # Configure Device C.

    [~DeviceC] isis 1
[*DeviceC-isis-1] network-entity 10.0000.0000.0003.00
[*DeviceC-isis-1] is-level level-1
[*DeviceC-isis-1] quit
[*DeviceC] interface gigabitethernet 0/1/0
[*DeviceC-GigabitEthernet0/1/0] isis enable 1
[*DeviceC-GigabitEthernet0/1/0] commit
[~DeviceC-GigabitEthernet0/1/0] quit

    # Configure Device D.

    [~DeviceD] isis 1
[*DeviceD-isis-1] network-entity 10.0000.0000.0004.00
[*DeviceD-isis-1] is-level level-2
[*DeviceD-isis-1] quit
[*DeviceD] interface gigabitethernet 0/1/0
[*DeviceD-GigabitEthernet0/1/0] isis enable 1
[*DeviceD-GigabitEthernet0/1/0] commit
[~DeviceD-GigabitEthernet0/1/0] quit

    # Display information about IS-IS neighbors of Device A.

    [~DeviceA] display isis peer
                          Peer information for ISIS(1)

  System Id     Interface          Circuit Id        State HoldTime Type     PRI
--------------------------------------------------------------------------------
0000.0000.0002  GE0/1/0            0000.0000.0001.01  Up   30s      L1(L1L2) 64 
0000.0000.0003  GE0/1/0            0000.0000.0001.01  Up   30s      L1       64 
0000.0000.0002  GE0/1/0            0000.0000.0001.01  Up   30s      L2(L1L2) 64 
0000.0000.0004  GE0/1/0            0000.0000.0001.01  Up   30s      L2       64 

Total Peer(s): 4

    # Display information about the IS-IS interface on Device A.

    [~DeviceA] display isis interface
                       Interface information for ISIS(1)
                       ---------------------------------
 Interface         Id      IPV4.State          IPV6.State      MTU  Type  DIS
 GE0/1/0          001         Up           Mtu:Up/Lnk:Dn/IP:Dn 1497 L1/L2 No/No

    # Display information about the IS-IS interface on Device B.

    [~DeviceB] display isis interface
                       Interface information for ISIS(1)
                       ---------------------------------
 Interface         Id      IPV4.State          IPV6.State      MTU  Type  DIS
 GE0/1/0          001         Up           Mtu:Up/Lnk:Dn/IP:Dn 1497 L1/L2 Yes/No

    # Display information about the IS-IS interface on Device D.

    [~DeviceD] display isis interface
                       Interface information for ISIS(1)
                       ---------------------------------
 Interface         Id      IPV4.State          IPV6.State      MTU  Type  DIS
 GE0/1/0          001         Up           Mtu:Up/Lnk:Dn/IP:Dn 1497 L1/L2 No/Yes

    As shown in the preceding interface information, when the default DIS priority is used, the interface on Device B has the largest MAC address among the interfaces on Level-1 devices. Therefore, Device B is elected as the Level-1 DIS. The interface on Device D has the largest MAC address among the interfaces on Level-2 devices. Therefore, Device D is elected as the Level-2 DIS. Level-1 and Level-2 pseudo nodes are 0000.0000.0002.01 and 0000.0000.0004.01, respectively.

  4. Configure the DIS priority of the IS-IS interface on Device A.

    [~DeviceA] interface gigabitethernet 0/1/0
[~DeviceA-GigabitEthernet0/1/0] isis dis-priority 100
[*DeviceA-GigabitEthernet0/1/0] commit

    # Display information about IS-IS neighbors of Device A.

    [~DeviceA] display isis peer
                          Peer information for ISIS(1)

  System Id     Interface          Circuit Id        State HoldTime Type     PRI
--------------------------------------------------------------------------------
0000.0000.0002  GE0/1/0            0000.0000.0001.01  Up   27s      L1(L1L2) 64 
0000.0000.0003  GE0/1/0            0000.0000.0001.01  Up   27s      L1       64 
0000.0000.0002  GE0/1/0            0000.0000.0001.01  Up   27s      L2(L1L2) 64 
0000.0000.0004  GE0/1/0            0000.0000.0001.01  Up   27s      L2       64 

Total Peer(s): 4

  5. Verify the configuration.

    # Display information about the IS-IS interface on Device A.

    [~DeviceA] display isis interface
                       Interface information for ISIS(1)
                       ---------------------------------
 Interface         Id      IPV4.State          IPV6.State      MTU  Type  DIS
 GE0/1/0          001         Up           Mtu:Up/Lnk:Dn/IP:Dn 1497 L1/L2 Yes/Yes

    As shown in the preceding information, after the DIS priority of the IS-IS interface is changed, Device A becomes a Level-1-2 DIS (DR) immediately, and its pseudo node is 0000.0000.0001.01.

    # Display information about IS-IS neighbors and the IS-IS interface on Device B.

    [~DeviceB] display isis peer
                          Peer information for ISIS(1)

  System Id     Interface          Circuit Id        State HoldTime Type     PRI
--------------------------------------------------------------------------------
0000.0000.0001  GE0/1/0            0000.0000.0001.01  Up   26s      L1(L1L2) 100 
0000.0000.0003  GE0/1/0            0000.0000.0001.01  Up   26s      L1       64 
0000.0000.0001  GE0/1/0            0000.0000.0001.01  Up   26s      L2(L1L2) 100 
0000.0000.0004  GE0/1/0            0000.0000.0001.01  Up   26s      L2       64 

Total Peer(s): 4
[~DeviceB] display isis interface
                       Interface information for ISIS(1)
                       ---------------------------------
 Interface         Id      IPV4.State          IPV6.State      MTU  Type  DIS
 GE0/1/0          001         Up           Mtu:Up/Lnk:Dn/IP:Dn 1497 L1/L2 No/No

    # Display information about IS-IS neighbors and the IS-IS interface on Device D.

    [~DeviceD] display isis peer
                          Peer information for ISIS(1)

  System Id     Interface          Circuit Id        State HoldTime Type     PRI
--------------------------------------------------------------------------------
0000.0000.0001  GE0/1/0            0000.0000.0001.01  Up   20s      L2       100 
0000.0000.0002  GE0/1/0            0000.0000.0001.01  Up   20s      L2       64 

Total Peer(s): 2
[~DeviceD] display isis interface
                       Interface information for ISIS(1)
                       ---------------------------------
 Interface         Id      IPV4.State          IPV6.State      MTU  Type  DIS
 GE0/1/0          001         Up           Mtu:Up/Lnk:Dn/IP:Dn 1497 L1/L2 No/No

Configuration Files

  • Device A configuration file

    #
sysname DeviceA
#
isis 1
 network-entity 10.0000.0000.0001.00
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 10.1.1.1 255.255.255.0
 isis enable 1
 isis dis-priority 100 level-1
 isis dis-priority 100 level-2
#
return

  • Device B configuration file

    #
sysname DeviceB
#
isis 1
 network-entity 10.0000.0000.0002.00
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 10.1.1.2 255.255.255.0
 isis enable 1
#
return

  • Device C configuration file

    #
sysname DeviceC
#
isis 1
 is-level level-1
 network-entity 10.0000.0000.0003.00
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 10.1.1.3 255.255.255.0
 isis enable 1
#
return

  • Device D configuration file

    #
sysname DeviceD
#
isis 1
 is-level level-2
 network-entity 10.0000.0000.0004.00
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 10.1.1.4 255.255.255.0
 isis enable 1
#
return
Parent Topic: IS-IS Configuration Examples
Copyright © Huawei Technologies Co., Ltd.
Copyright © Huawei Technologies Co., Ltd.
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