Creating an IPv4 IS-IS Process

To configure basic IPv4 IS-IS functions, first create an IPv4 IS-IS process and enable IPv4 IS-IS interfaces.

Context

To create an IS-IS process, perform the following operations:

Create an IS-IS process and configure the NET of a device.
(Optional) Configure the level of a device.

Configure the device level based on the network planning. If no device level is configured, IS-IS establishes separate neighbor relationships for Level-1 and Level-2 devices and maintains two identical LSDBs, consuming excessive system resources.
(Optional) Configure IS-IS host name mapping.

After IS-IS host name mapping is configured, a host name rather than the system ID of a device is displayed when you run a display command. This configuration improves the maintainability on an IS-IS network.
(Optional) Enable IS-IS adjacency strict-check.

If both IPv4 and IPv6 run on a network, and the IPv6 topology type of this network is standard or compatible, enable IS-IS adjacency strict-check to ensure that an IS-IS adjacency is established only when both IPv4 and IPv6 go Up. IS-IS adjacency strict-check improves network reliability and prevents traffic losses.
(Optional) Enable the alarm function for the number of LSPs in the LSDB.

An IS-IS-capable router may advertise a large number of LSPs due to an excessive number of external routes received because of incorrect configurations or attack packets. In this situation, you can configure alarm and clear alarm thresholds for the number of LSPs in the LSDB. When the proportion of the number of LSPs to the maximum number of LSPs in the LSDB exceeds the alarm threshold, an alarm is generated; when the proportion of the number of LSPs to the maximum number of LSPs in the LSDB falls below the clear alarm threshold, a clear alarm is generated.
(Optional) Configure IS-IS to add purge originator identification (POI) TLV to purge LSPs.

This function helps locate the source of error packets when a fault occurs on the network.
(Optional) Disable automatic IS-IS system ID recovery in case of conflicts.

Two devices on an IS-IS network cannot have the same system ID. Otherwise, network flapping may occur.

Procedure

Create an IS-IS process and configure the NET of a device.
1. Run system-view
  The system view is displayed.
2. Run isis [ process-id ]
  An IS-IS process is created, and its view is displayed.
  
  The process-id parameter specifies the ID of an IS-IS process. If the process-id parameter is not specified, the default value 1 is used. An IS-IS process can be associated with a VPN instance using the isis process-id vpn-instance vpn-instance-name command.
3. Run network-entity net-addr
  A NET is configured.
  NET of IS-IS consists of three parts:
  - Area ID, which is variable (1 to 13 bytes).
  - System ID (6 bytes) of this device.
  - SEL, which is 1 byte and its value must be 00.
  For example, the NET of IS-IS device can be configured as 10.1234.6e9f.0001.00.
  An area ID is used to uniquely identify an area in the same IS-IS domain. All routers in the same Level-1 area must share the same area ID, while routers in the same Level-2 area can have different area IDs.
  The system ID must be unique in the whole area and backbone area.
  Multiple NETs can be configured, but they must have the same system ID.
  Configuring loopback interface addresses based on NETs is recommended to ensure that a NET is unique on the network. If NETs are not unique, route flapping will easily occur. The system ID can be converted from a loopback interface IP address in the following way: extend each part of the IP address to 3 bits, add 0 to the front of any part that is shorter than 3 bits, divide the extended address into three parts, with each part consisting of four decimal digits, and the reconstructed address is the system ID.
4. (Optional) Run description description
  A description is configured for the IS-IS process.
  
  Configuring a description for an IS-IS process facilitates device maintenance and management. The description is not advertised through LSPs.
5. Run commit
  The configuration is committed.
(Optional) Configure the level of a device.
1. Run is-level { level-1 | level-1-2 | level-2 }
  The level of the router is configured.
2. Run commit
  The configuration is committed.
(Optional) Configure IS-IS host name mapping.
1. Run is-name symbolic-name
  IS-IS dynamic host name mapping is configured. The system ID of the local device is mapped to the specified host name.
  
  The value of symbolic-name is contained in LSP packets and advertised to other IS-IS devices.
  
  symbolic-name rather than the system ID of the local IS-IS device is displayed on another IS-IS device.
2. Run is-name map system-id symbolic-name
  IS-IS static host name mapping is configured. The system ID of a peer IS-IS device is mapped to the specified host name.
  
  This command configuration takes effect only on the local IS-IS device. The value of symbolic-name will not be added to LSPs.
  
  If dynamic host name mappings are configured on an IS-IS network, the mappings on the network override those statically configured on the local router.
3. Run commit
  The configuration is committed.
(Optional) Enable IS-IS adjacency strict-check.
1. Run adjacency-strict-check enable
  IS-IS adjacency strict-check is enabled.
2. Run commit
  The configuration is committed.
(Optional) Enable the alarm function for the number of LSPs in the LSDB.
1. Run lsdb limit limit-number threshold-alarm upper-limit upper-limit-value lower-limit lower-limit-value
  The alarm function is enabled for the number of LSPs in the LSDB.
  
  upper-limit-value must be greater than or equal to lower-limit-value.
2. Run commit
  The configuration is committed.
(Optional) Configure IS-IS to add POI TLV to purge LSPs.
1. Run the purge-originator-identification enable [ always ] command to configure IS-IS to add the POI TLV (as well as the hostname TLV if the dynamic hostname function is enabled) to purge LSPs.
  - If the purge-originator-identification enable command is run and the send-only parameter is specified when configuring authentication, generated purge LSPs do not carry the POI TLV or hostname TLV.
  - If the purge-originator-identification enable command is run and HMAC-MD5 authentication is configured, generated purge LSPs do not carry the POI TLV or hostname TLV. If the command is run and authentication of another type is configured or no authentication is configured, generated purge LSPs carry the POI TLV and hostname TLV.
    
    HMAC-SHA256 rather than HMAC-MD5 is recommended for the sake of security.
  - If the purge-originator-identification enable always command is run, generated purge LSPs carry the POI TLV and hostname TLV, regardless of whether authentication is configured or whether the send-only parameter is specified when configuring authentication.
2. Run commit
  The configuration is committed.
(Optional) Disable automatic IS-IS system ID recovery in case of conflicts.
1. Run quit
  Return to the system view.
2. Run isis system-id auto-recover disable
  Automatic IS-IS system ID recovery is disabled in case of conflicts.
3. Run commit
  The configuration is committed.