Configuring the IS-IS Packet Timer

The Hello timer, Hello dead timer, Minimum Interval for Sending LSPs can be configured for IS-IS. You can adjust these attribute values to affect the network aggregation rate according to the actual network environment and router performance.

Context

IS-IS maintains the neighboring relation with the neighboring router by receiving and sending Hello packets. When the local router does not receive the Hello packets sent from the peer end for a while, the local router identifies that the neighboring router is invalid.

In IS-IS, you can set the number of invalid Hello packets and interval for sending Hello packets to control the period for keeping the neighboring relation between the local router and neighboring router.

There are level-1 and level-2 Hello packets on the broadcast link and different values can be specified for different types of packets. If the level is not specified, by default both parameters level-1 and level-2 are specified. There is only one type of Hello packets on the P2P link. Therefore, parameters level-1 and level-2 do not need to be specified.

Procedure

Set the interval for sending Hello packets.
1. Access the system view.
  system-view
2. Access the interface view.
  interface interface-type interface-number
3. Set an interval for sending Hello packets on the interface.
  isis timer hello hello-interval1 [ level-1 | level-2 ]
  
  On a broadcast link, there are Level-1 and Level-2 Hello packets. For different types of packets, you can set different intervals. If no level is specified, both the Level-1 timer and Level-2 timer are configured. On a P2P link, only one type of Hello packets exist. Therefore, neither level-1 nor level-2 is required.
  
  Parameters level-1 and level-2 are only visible on broadcast interfaces and IS-IS must be enabled on the interfaces.
Set the number of invalid Hello packets.
1. Access the system view.
  system-view
2. Access the interface view.
  interface interface-type interface-number
3. Set the number of invalid Hello packets.
  isis timer holding-multiplier number [ level-1 | level-2 ]
  
  If the level is not specified, by default both parameters level-1 and level-2 are specified.
  
  Parameters level-1 and level-2 are only visible on broadcast interfaces and IS-IS must be enabled on the interfaces.
  
  IS-IS maintains neighbor relationships with neighbors through Hello packets. If the local router does not receive any Hello packet from a neighbor within holding time, the local router declares that the neighbor is invalid.
  
  In IS-IS, the period during which the local router and its neighbor keep the neighbor relationship is determined by the invalid number of Hello packets and the interval for sending Hello packets.
Set the interval for sending CSNP packets.
1. Access the system view.
  system-view
2. Access the interface view.
  interface interface-type interface-number
3. Set an interval for sending CSNP packets on the interface.
  isis timer csnp csnp-interval [ level-1 | level-2 ]
CSNP packets are packets sent by LSDB that the Designated IS (DIS) synchronizes on the broadcast network. If parameter level-1 or level-2 is not specified in the command, by default the broadcast level of the CSNP packets of the current level is specified.
Configuring the Interval for Retransmitting LSPs
1. Access the system view.
  system-view
2. Access the interface view.
  interface interface-type interface-number
3. Set an interval for retransmitting LSPs on a P2P link.
  isis timer lsp-retransmit retransmit-interval
  
  On a P2P link, if the local router does not receive the response within a period of time after it sends an LSP, it considers that the LSP is lost or dropped. To ensure the reliable transmission, the local router retransmits the LSP according to the retransmit-interval. By default, the interval for retransmitting the LSP packet on the P2P link is 5 seconds.
  
  The LSPs sent on a broadcast link do not need any response.
Set the minimum interval for the interface to send the LSP.
1. Access the system view.
  system-view
2. Access the interface view.
  interface interface-type interface-number
3. Set an interval for the interface to send the LSP.
  isis timer lsp-throttle throttle-interval [ count count ]
  
  count specifies the maximum number of LSPs sent during throttle-interval. The value is an integer ranging from 1 to 1000.
You can set the minimum interval for IS-IS to send LSPs on the interface, that is, the interval between two continuous LSPs. The interval is also the interval for sending the fragments of CSNP packets.