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 9-14:
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).
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 |
DeviceD |
GE0/1/0 |
10.1.1.4/24 |
Configuration Roadmap
The configuration roadmap is as follows:
Enable IS-IS and specify the NET on each NE for interworking.
View information about the IS-IS interface on each NE with the default DIS priority.
Configure the DIS priority of the interface on each NE.
Data Preparation
To complete the configuration, you need the following data:
Area addresses of the four NEs
Levels of the four NEs
DIS priority of the interface on Device A
Procedure
- Configure an IPv4 address for each interface. For configuration details, see Configuration Files in this section.
- Display the MAC address of the GE interface on each NE. When the DIS priority of each interface is the same, the NE 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-fcfd-305c I GE0/1/0 ------------------------------------------------------------------------- Total:1 Dynamic:0 Static:0 Interface:1 Remote:0 Redirect:0
- 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.
- 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
- 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