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Fat AP and Cloud AP V200R008C00 CLI-based Configuration Guide

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Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
Configuring BFD

Configuring BFD

This section describes how to configure BFD.

Configuring Single-Hop BFD

Single-hop BFD fast detects faults on the directly connected link.

Pre-configuration Tasks

Before configuring single-hop BFD, complete the following tasks:

  • Configuring link layer protocol parameters for interfaces to ensure that the link layer protocol status on the interfaces is Up

  • Configuring an IP address for the Layer 3 interface

Configuration Process
Figure 24-4  Single-hop BFD configuration process

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    bfd

    BFD is enabled globally and the BFD view is displayed.

    By default, BFD is disabled globally.

  3. (Optional) Run:

    default-ip-address ip-address

    The default multicast IP address for BFD is configured.

    By default, BFD uses the multicast IP address 224.0.0.184.

    NOTE:

    If multiple BFD sessions exist on a path, for example, Layer 3 interfaces are connected through Layer 2 switching devices that support BFD, configure different default multicast IP addresses for the devices where different BFD sessions are established. In this manner, BFD packets can be correctly forwarded.

  4. Run:

    quit

    Return to the system view.

  5. Run the following commands as required.

    • On a Layer 3 interface that has an IP address configured, run:

      bfd session-name bind peer-ip ip-address interface interface-type interface-number [ source-ip ip-address ]

      A BFD binding is configured.

      NOTE:
      • When creating a single-hop BFD session for the first time, bind the single-hop BFD session to the peer IP address and the local address. To modify a configured BFD session, delete it and recreate a new one.

      • When the BFD configuration items are created, the system checks only the format of the IP address. The BFD session cannot be established if an incorrect peer IP address or source IP address is bound.

      • When BFD and URPF are used together, URPF checks the source IP address of the received BFD packets. You must bind the correct source IP address to the BFD session to prevent BFD packets from being discarded incorrectly.

      • BFD cannot detect route switching. If the bound peer IP address change causes route switching, BFD does not perform re-negotiation unless forwarding fails on the original link.

    • On a Layer 2 interface, Layer 3 interface, run:

      bfd session-name bind peer-ip default-ip interface interface-type interface-number [ source-ip ip-address ]

      Multicast BFD is created.

      NOTE:

      When creating a multicast BFD session on a Layer 3 interface, configure an IP address for the interface so that the protocol layer becomes Up. Otherwise, the BFD session cannot become Up.

  6. Run:

    discriminator local discr-value

    The local discriminator is set.

  7. Run:

    discriminator remote discr-value

    The remote discriminator is set.

    NOTE:
    • The local discriminator of the local system must be the same as the remote discriminator of the remote system; the remote discriminator of the local system must be the same as the local discriminator of the remote system. Otherwise, BFD sessions cannot be established. After the local discriminator and the remote discriminator are configured, you cannot modify them.

    • If a BFD session is bound to the default multicast address, the local discriminator and the remote discriminator must be different.

  8. Run:

    commit

    The configuration is committed.

Configuring Multi-Hop BFD

Multi-hop BFD fast detects faults on the indirectly connected link.

Pre-configuration Tasks

Before configuring multi-hop BFD, complete the following task:

  • Configuring a routing protocol to ensure reachability at the network layer

Configuration Process
Figure 24-5  Multi-hop BFD configuration process

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    bfd

    BFD is enabled globally and the BFD view is displayed.

  3. Run:

    quit

    Return to the system view.

  4. Run:

    bfd session-name bind peer-ip ip-address [ source-ip ip-address ]

    A BFD session is created and the peer IP address is specified.

    NOTE:
    • When creating a multi-hop BFD session, you must bind the BFD session to the peer IP address.

    • When the BFD configuration items are created, the system checks only the format of the IP address. The BFD session cannot be established if an incorrect peer IP address or source IP address is bound.

  5. Run:

    discriminator local discr-value

    The local discriminator is set.

  6. Run:

    discriminator remote discr-value

    The remote discriminator is set.

    NOTE:

    The local discriminator of the local system must be the same as the remote discriminator of the remote system; the remote discriminator of the local system must be the same as the local discriminator of the remote system. Otherwise, BFD sessions cannot be established. After the local discriminator and the remote discriminator are configured, you cannot modify them.

  7. Run:

    commit

    The configuration is committed.

Configuring Static BFD with Automatically Negotiated Discriminators

When the peer device uses dynamic BFD and the local device wants to communicate with the peer device and detect static routes, create a BFD session with automatically negotiated discriminators.This function applies to networks that use static routes to implement Layer 3 connectivity.

Pre-configuration Tasks

Before configuring a BFD session with automatically negotiated discriminators, complete the following task:

  • Configuring an IP address for the Layer 3 interface

Configuration Process
Figure 24-6  Configuring static BFD with automatically negotiated discriminators

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    bfd

    BFD is enabled globally and the BFD view is displayed.

    By default, BFD is disabled globally.

  3. Run:

    quit

    Return to the system view.

  4. Run:

    bfd session-name bind peer-ip ip-address [ interface interface-type interface-number ] source-ip ip-address auto

    A BFD session with automatically negotiated discriminators is created.

    NOTE:
    • You must specify a source IP address.

    • You must specify the peer IP address, which cannot be a multicast IP address.

  5. Run:

    commit

    The configuration is committed.

Configuring the BFD Echo Function

The BFD echo function detects fast detect faults on directly connected links.

Pre-configuration Tasks

Before configuring the BFD echo function, complete the following tasks:

  • Connecting interfaces properly

  • Correctly configuring an IP address for the Layer 3 interface

Configuration Process
Figure 24-7  Configuration process of the BFD echo function

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    bfd

    BFD is enabled globally and the BFD view is displayed.

  3. Run:

    quit

    Return to the system view.

  4. Run:

    bfd session-name bind peer-ip peer-ip interface interface-type interface-number [ source-ip ip-address ] one-arm-echo

    A BFD session supporting the BFD echo function is configured.

    NOTE:
    • The BFD echo function is only applicable to single-hop BFD sessions.

    • BFD cannot detect route switching. If the bound peer IP address changes, BFD does not perform negotiation again.

  5. Run:

    discriminator local discr-value

    The discriminator for the BFD session is configured.

    You can only configure the local discriminator because the BFD echo function is only configured on one device supporting BFD.

  6. Run:

    commit

    The configuration is committed.

Configuring BFD Association

Association between BFD and other protocols improves protocol switching performance and reduces service traffic loss.

Applications Associated with BFD
Configuring Association Between the BFD Session and the Interface Status

Pre-configuration Tasks

Before associating the BFD session with interface status, complete the following task:

  • Connecting interfaces properly

Configuration Process
Figure 24-8  Association between the BFD session and the interface status

Context

If a transmission device exists on a direct link, BFD detects a link fault faster than a link protocol on an interface. The link protocol status of a trunk or VLANIF interface depends on the link protocol status of member interfaces.

To help BFD rapidly report the detection result to the application, a BFD status attribute is added to the interface management module of each interface. This attribute indicates the status of the BFD session that is bound to the interface. The system obtains the interface status based on the link status, protocol status, and BFD status on the interface, and then reports the interface status to the application.

This function is only used on the single-hop BFD session that is bound to an outbound interface and uses the default multicast address.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    bfd

    BFD is enabled globally and the BFD view is displayed.

  3. (Optional) Run:

    default-ip-address ip-address

    The default multicast IP address for BFD is configured.

    By default, BFD uses the multicast IP address 224.0.0.184.

    NOTE:

    If multiple BFD sessions exist on a path, for example, Layer 3 interfaces are connected through Layer 2 switching devices that support BFD, configure different default multicast IP addresses for the devices where different BFD sessions are established. In this manner, BFD packets can be correctly forwarded.

  4. Run:

    quit

    Return to the system view.

  5. Run:

    bfd session-name bind peer-ip default-ip interface interface-type interface-number [ source-ip ip-address ]

    A BFD session is created.

    NOTE:

    When creating a multicast BFD session on a Layer 2 interface, configure a PVID on the interface to ensure that BFD packets can be transmitted at Layer 2.

  6. Run:

    discriminator local discr-value

    The local discriminator of the BFD session is configured.

  7. Run:

    discriminator remote discr-value

    The remote discriminator of the BFD session is configured.

    NOTE:
    • The local discriminator of the local system must be the same as the remote discriminator of the remote system; the remote discriminator of the local system must be the same as the local discriminator of the remote system. Otherwise, BFD sessions cannot be established. After the local discriminator and the remote discriminator are configured, you cannot modify them.

    • If a BFD session is bound to the default multicast address, the local discriminator and the remote discriminator must be different.

  8. Run:

    process-interface-status [ sub-if ] [ reboot-no-impact ]

    The BFD session status is associated with the bound interface status.

    By default, the BFD session status is not associated with the interface status. That is, the change of the BFD session status does not affect the interface status.

  9. Run:

    commit

    The configuration is committed.

    NOTE:
    • The BFD session does not report the BFD status to the bound interface immediately after the commit command is executed because the BFD session may not be set up or not Up. This prevents the BFD session from reporting an incorrect state to the interface. When the BFD status changes, the BFD session reports the BFD status to the interface to trigger the interface status change.

    • If the process-interface-status [ sub-if ] [ reboot-no-impact ] command has been saved in the configuration file, the initial interface status must be Down after the device restarts; therefore, the BFD session reports a Down state to the interface.

Adjusting BFD Parameters

You can adjust BFD time parameters as needed.

Pre-configuration Tasks

Before adjusting BFD parameters, complete the following task:

  • Creating a BFD session

Adjusting the BFD Detection Time

Context

When you set up a BFD session, you can adjust the minimum interval for sending BFD packets, minimum interval for receiving BFD packets, and local detection multiplier based on the network situation and performance requirements.

To reduce usage of system resources, when a BFD session is detected in Down state, the system adjusts the minimum interval for receiving BFD packets and the minimum interval for sending BFD packets to random values greater than 1000 ms. When the BFD session becomes Up, the configured intervals are restored.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    bfd bfd-name

    The BFD session view is displayed.

  3. Run:

    min-tx-interval interval

    The minimum interval for sending BFD packets is set.

    By default, the minimum interval for sending BFD packets is 30 ms.

  4. Run:

    min-rx-interval interval

    The minimum interval for receiving BFD packets is set.

    By default, the minimum interval for receiving BFD packets is 30 ms.

    NOTE:

    To reduce usage of system resources, when a BFD session is detected in Down state, the system adjusts the minimum interval for receiving BFD packets and the minimum interval for sending BFD packets to random values greater than 1000 ms. When the BFD session becomes Up, the configured intervals are restored.

  5. Run:

    detect-multiplier multiplier

    The local detection multiplier is set.

    By default, the local detection multiplier is 3.

Setting the WTR Time of a BFD Session

Context

If a BFD session flaps, an active/standby switchover is frequently performed on the application associated with the BFD session. To prevent the problem, set the WTR time of the BFD session. When the BFD session changes from Down to Up, BFD reports the change to the upper layer application only after the WTR timer times out.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    bfd bfd-name

    The BFD session view is displayed.

  3. Run:

    wtr wtr-value

    The WTR time is set.

    By default, the WTR time is 0, indicating that the status change of a BFD session is reported immediately.

    NOTE:

    If the WTR time is set, set the same WTR time at both ends. Otherwise, when the BFD session status changes at one end, applications at both ends detect different BFD session statuses.

Configuring the Description for a BFD Session

Context

To differentiate BFD sessions, configure the description for BFD sessions.

NOTE:

The description (BFD session view) command is valid for only static BFD sessions, and is invalid for dynamic BFD sessions and BFD sessions with automatically negotiated parameters.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    bfd bfd-name

    The BFD session view is displayed.

  3. Run:

    description description

    The description of the BFD session is configured.

    By default, the description of a BFD session is empty.

Setting the Global TTL Value

Context

When devices running different versions interwork with each other, the TTL values and detection modes on both ends of the BFD session are different and BFD packets are discarded. You can set the global TTL value to enable the Huawei device to interwork with each other in different versions, with upgraded devices, and with non-Huawei devices.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    bfd

    BFD is enabled globally on the local node and the BFD view is displayed.

  3. Run:

    peer-ip peer-ip mask-length ttl { single-hop | multi-hop } ttl-value

    The TTL value of BFD control packets is set.

    NOTE:
    • The TTL value of BFD packets varies with the BFD session type. By default, for a static BFD session, the TTL value of a single-hop BFD packet is 255 and the TTL value of a multi-hop BFD packet is 254. For a dynamic BFD session, the TTL value of a single-hop BFD packet is 255 and the TTL value of a multi-hop BFD packet is 253.

    • After the TTL value in multi-hop BFD packets is configured, you must configure the same peer IP address, mask length longer than the mask length for the TTL value in multi-hop BFD packets, and TTL value in single-hop BFD packets. This is because the TTL value in multi-hop BFD packets affects dynamic single-hop BFD sessions.

Setting the Priority of BFD Packets

You can change the priority of BFD packets to:

  • Detect whether packets with different priorities on a link can be forwarded.

  • Ensure that BFD packets with a higher priority are forwarded first.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    bfd bfd-name

    The BFD session view is displayed.

  3. Run:

    tos-exp tos-value

    The priority of BFD packets is set.

    By default, the priority of BFD packets is 7, representing the highest priority. The value 0 is the lowest priority.

Setting the Interval for Sending Traps

Context

If the BFD module is enabled with the SNMP alarm function, the NMS will receive BFD Up or Down messages. If the BFD session flaps, the NMS receives a large number of traps. In this case, BFD traps need to be suppressed. Run the snmp-agent bfd trap-interval command to set the interval at which traps are sent to prevent overflow of traps.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    bfd

    BFD is enabled globally and the BFD view is displayed.

  3. Run:

    snmp-agent bfd trap-interval interval

    The interval at which traps are sent is set.

    By default, the interval at which traps are sent is 120s.

Checking the Configuration

After the BFD configuration is complete, you can view the BFD session configuration.

Procedure

  • Run the display bfd interface [ interface-type interface-number ] command to check the BFD-enabled interface.
  • Run the display bfd session { all | static | discriminator discr-value | dynamic | peer-ip { default-ip | peer-ip } | static-auto } [ verbose ] command to view information about the BFD session.
  • Run the display bfd statistics command to check global BFD statistics.
  • Run the display bfd statistics session { all | static | dynamic | discriminator discr-value | peer-ip default-ip | peer-ip peer-ip | static-auto } command to check BFD session statistics.
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Updated: 2019-01-11

Document ID: EDOC1000176006

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