Configuring Dynamic BFD for IPv6 IS-IS

Context

The switch supports dynamic BFD for IPv6 IS-IS, but not static BFD for IPv6 IS-IS.

Without BFD, connection status between an IS-IS device and its neighbors can be monitored only by exchanging Hello packets at intervals. The minimum allowable sending interval is 3s, and a neighbor is declared Down after at least three intervals during which no response Hello packet is received from the neighbor. IS-IS takes more than one second to detect that a neighbor becomes Down, resulting in loss of a large amount of high-speed data.

BFD provides millisecond-level fault detection. After detecting a link or node failure, BFD will notify IS-IS of the failure. Traffic is rapidly switched to the backup link or node.

Only the S5720-EI, S5720-HI, S5730-HI, S5731-H, S5731-S, S5731S-H, S5731S-S, S5732-H, S6720-EI, S6720-HI, S6720S-EI, S6730-H, S6730S-H, S6730-S, and S6730S-S BFD for IS-IS.

Pre-configuration Tasks

Before configuring dynamic BFD for IPv6 IS-IS, complete the following tasks:

Configure IPv6 addresses for interfaces to ensure that neighbor nodes are reachable.
Configure IPv6 IS-IS functions to ensure that each node is reachable at the network layer.

Configuration Roadmap

The configuration roadmap is as follows:

No.	Data
1	Nodes to be enabled with BFD for IPv6 IS-IS
2	Number of the IS-IS process to be enabled with BFD
3	Type and number of each interface to be enabled with BFD
4	Minimum interval at which BFD packets are sent
5	Minimum interval at which BFD packets are received
6	BFD detection multiplier

No.

Data

Nodes to be enabled with BFD for IPv6 IS-IS

Number of the IS-IS process to be enabled with BFD

Type and number of each interface to be enabled with BFD

Minimum interval at which BFD packets are sent

Minimum interval at which BFD packets are received

BFD detection multiplier

You can use either of the following methods to enable BFD for IPv6 IS-IS:

Enable dynamic BFD for specified IS-IS IPv6 processes. This method is recommended if you need to enable dynamic BFD for IPv6 IS-IS on a large number of IS-IS interfaces.
Enable dynamic BFD for specified IPv6 interfaces. This method is recommended if you need to enable dynamic BFD for IPv6 IS-IS on a small number of IS-IS interfaces.

Procedure

Enable dynamic BFD for an IS-IS IPv6 process.
1. Run system-view
  The system view is displayed.
2. Run bfd
  BFD is enabled globally.
3. Run quit
  The system view is displayed.
4. Run isis process-id
  The IS-IS view is displayed.
5. Run ipv6 bfd all-interfaces enable
  BFD for IS-IS is enabled.
  
  After BFD is enabled globally and the neighbor status is Up, default BFD parameters will be used to establish BFD sessions on all interfaces.
6. (Optional) Run ipv6 bfd all-interfaces { min-rx-interval receive-interval | min-tx-interval transmit-interval | detect-multiplier multiplier-value } ^*
  The parameters for establishing BFD sessions are set for all interfaces.
  
  The command execution result is applicable to BFD session parameters on all IS-IS interfaces.
7. Run quit
  The system view is displayed.
  
  To disable the BFD function on an interface, run the isis ipv6 bfd block command in the interface view to disable the interface from establishing BFD sessions.
Enable dynamic BFD on an IS-IS IPv6 interface.
1. Run system-view
  The system view is displayed.
2. Run bfd
  BFD is enabled globally.
3. Run quit
  The system view is displayed.
4. Run interface interface-type interface-number
  The view of the specified interface is displayed.
5. (Optional) On an Ethernet interface, run undo portswitch
  The interface is switched to Layer 3 mode.
  
  By default, an Ethernet interface works in Layer 2 mode.
  
  Only the S5720-EI, S5720-HI, S5730-HI, S5731-H, S5731-S, S5731S-H, S5731S-S, S5732-H, S6720-EI, S6720-HI, S6720S-EI, S6730-H, S6730S-H, S6730-S, and S6730S-S support switching between Layer 2 and Layer 3 modes.
6. Run isis ipv6 bfd enable
  BFD is enabled on the interface.
7. (Optional) Run isis ipv6 bfd { min-rx-interval receive-interval | min-tx-interval transmit-interval | detect-multiplier multiplier-value } ^*
  Run this command when BFD session parameters need to be configured for a specified interface.

Verifying the Configurations

After configuring dynamic BFD for IPv6 IS-IS, you can check information about the BFD session and BFD for IPv6 IS-IS on an interface.

Run the display isis [ process-id | vpn-instance vpn-instance-name ] ipv6 bfd session { all | peer ipv6-address | interface interface-type interface-number } command to check information about a BFD session.
Run the display isis [ process-id ] ipv6 bfd interface command to check the configurations of BFD for IPv6 IS-IS on the specified interface.