Feature Requirements |
Series |
Models |
|---|---|---|
The source and destination fields of an Echo packet are filled with the IP address of the local outbound interface. After receiving a packet, strict URPF checks the source and interface, and therefore discards the packet. As a result, route flapping occurs. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
The local discriminator on one end must be the same as the remote discriminator on the other end. Otherwise, the BFD session cannot be established. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
If the wait to restore (WTR) time is used, you need to configure the same WTR time at both ends. Otherwise, when the BFD session state changes at one end, applications at both ends detect different BFD session states. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
The BFD detection interval of the inner-layer link must be less than that of the outer-layer link. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
The outbound interface of BFD for peer IPv6 is a dot1q/QinQ VLAN tag termination sub-interface and multiple VLANs are configured the sub-interface, you must ensure that the VLAN IDs learned by the ND modules on both ends are the same. If they are different, the BFD session cannot go Up. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
In a BFD for IP session, negotiation packets are forcibly transmitted over the active link. Detection packets are forwarded along the same path as the service packets. This solution has the following limitations:: 1. The S-BFD reflector has no state machine. Therefore, this solution cannot solve the problem that occurs when S-BFD return traffic sent by the reflector is transmitted along a tunnel after the IP route recurses to the tunnel. 2. When the primary LSP is normal but the BFD session is Down and the backup LSP is faulty, BFD negotiation packets can be transmitted over the primary LSP and go Up through negotiation. However, BFD detection packets cannot be transmitted. As a result, the BFD session flaps. 3. In an IP over a static protection group scenario, when BFD return packets are transmitted along a tunnel in a static protection group to which an IP route recurses, BFD negotiation fails if the primary tunnel of the static protection group is Down. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
BFD for IPv4/IPv6 cannot be bound to a local host IP address. bfd XX bind peer-ip/peer-ipv6 X.X.X.X The message "Error:The IP address configured for the peer is the local IP address." Indicates a configuration failure. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
BFD for IPv4/IPv6 cannot be bound to a VRRP virtual IP address. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
When the outbound interface of a BFD for peer IP session is a dot1q/QinQ VLAN tag termination sub-interface and multiple VLANs are configured on the sub-interface, you must ensure that the VLAN IDs learned by the ARP modules on both ends are the same. If they are different, the BFD session cannot go Up. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
In SBFD for SR-MPLS BE tunnel scenarios, when SR-MPLS BE tunnels work in load balancing mode, SBFD packets are forwarded from a link through hashing. If this link is faulty, the SBFD session goes Down. The SR-MPLS BE tunnel is incorrectly detected as Down, triggering a service switchover. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
In SBFD for SR-MPLS BE tunnel scenarios, the configured packet sending interval must be greater than the switching time inside the tunnel. Otherwise, SBFD is incorrectly detected as Down, triggering a service switchover. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
S-BFD sessions can be established when one reflector connects to multiple initiators. The total number of sessions on the initiators cannot exceed the upper limit supported by the reflector, preventing session flapping. You are advised to plan the network properly to ensure that the number of S-BFD sessions established on a reflector does not exceed upper limit supported by the reflector. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
When BFD detects a dot1q VLAN tag termination sub-interface in default IP mode, the minimum VLAN IDs in the VLAN ID ranges configured at both ends must be the same, and the dot1q VLAN tag stermination sub-interface cannot be bound to a VSI. Otherwise, the BFD session fails to go Up. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
In SBFD for SR-MPLS BE tunnel scenarios, packet loss occurs during switchback inside the SR-MPLS BE tunnel when upstream and downstream traffic is transmitted through different boards. As a result, the SBFD session may go Down, which triggers service switching. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
BFD packets do not support reassembly. The MTU of the outbound interface on the device that BFD packets pass through must be greater than or equal to 52 bytes. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
In SBFD for SR-MPLS BE tunnel scenarios, if the transmission and reflection paths are different and the reflection path fails, the SR-MPLS BE tunnel is incorrectly detected as Down, triggering a service switchover. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
During BFD for IS-IS, OSPF, RIP, and BGP configuration, if the link outbound interface is an Eth-Trunk interface and the configured BFD detection period is less than or equal to 300 ms, the BFD status may go Down. In the IS-IS/OSPF/RIP view, run the following command:bfd all-interfaces enable In the BGP view, run the following command: peer <ip-address> bfd enable You are advised to configure the BFD detection period to be greater than 300 ms. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
For the same detection object (LDP LSP, TE tunnel, or TE LSP), a maximum of eight static BFD sessions can be configured, and a maximum of 200 static BFD sessions of the IP type can be configured. This limit applies to configuration delivery not configuration restoration. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
If BFD for default IP is configured on two indirectly connected devices, for the intermediate device, you are advised to disable BFD or configure a default IP address that is different from the default IP addresses of the two devices. Otherwise, BFD cannot go Up. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
When a static BFD for single-hop session is bound to a flexible access sub-interface, the priority of the BFD session must be included in the priority range of the flexible access sub-interface. If the priority of a BFD session is not within the priority range of its bound flexible access sub-interface, the BFD session cannot go Up. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
SBFD no-bypass for an SRv6 TE Policy: This function does not take effect for devices that do not support SRv6. This is because only an SRv6-capable device can parse the SRH header that carries the no-bypass flag. An SRv6-incapable device does not parse the SRH header, and therefore cannot identify the no-bypass flag. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
The reflector cannot distinguish VSs when processing SBFD packets. On the same physical device, outgoing SBFD packets of a tunnel from a VS may incorrectly match the reflector discriminator configured for a different VS. You are advised to plan SBFD initiator and reflector configurations in VSs Properly. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
In an SRv6 TE Policy loose path computation scenario where SBFD no-bypass is configured for an SRv6 TE Policy, if the primary path fails, BFD goes down first. After route convergence is complete and traffic is switched to the backup path, BFD goes up again through negotiation. However, traffic is still transmitted along the original backup path. Traffic is switched to the local protection path. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
In forwarding by MPLS tunnel labels, the BFD receiving process cannot distinguish VSs. On a physical device, the BFD packets that are sent out of the tunnel through a VS are mismatched with the BFD descriptors configured in other VSs. You are advised to plan BFD for VSs Properly. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
If the return paths of the primary and backup S-BFD sessions reach the initiator along the same route, both the primary and backup S-BFD sessions go Down if the return paths are disconnected. The primary and backup TE LSPs' status detection is affected. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
SBFD for SR-MPLS TE LSP supports transmission of return traffic over a tunnel. After this function is enabled, the SBFD session established between a Huawei device and a non-Huawei device may be down. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
SBFD no-bypass for an SRv6 TE Policy: SBFD and actual service traffic may be transmitted along different links if SBFD monitors multiple physical links that load balance traffic. In this case, SBFD goes down, but traffic can be forwarded or traffic is interrupted, but SBFD is up. If the SBFD session is up but the actual service path is unavailable, service traffic is switched to another load balancing path. If the SBFD session is down, service traffic will not be switched to another load balancing path. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
If the local and remote discriminators of a BFD session are different and the Loopback local command is enabled on the local end's outbound interface, the BFD status is unpredictable because the local end receives both packets sent and loopbacked by the remote end. You are advised to not configure the Loopback local command on the outbound interface from which BFD packets are sent. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
In the network slicing scenario, the SBFD for SRv6 TE Policy forcibly uses the slice interface. If the link of the slice interface is disconnected, the SBFD detection is down. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
Local protection is forcibly disabled for SBFD for SRv6 TE Policy in network slicing scenarios. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
When a U-BFD session is deployed to track an SRv6 TE Policy and local protection (TE FRR/TI-LFA) is enabled on the detection path, the BFD no-bypass function needs to be configured. Otherwise, the link detected by BFD may be different from the actual link. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
U-BFD for SRv6 TE Policy list must be used together with the BFD no-bypass function. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
The egress does not verify the discriminators in BFD packets. When the SID stack configuration is incorrect, the U-BFD session for SRv6 TE Policy list may incorrectly go up. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
When the last SID node of an Srv6 TE Policy in encap mode fails, public network traffic cannot be forwarded on the faulty node. However, BFD fails in this scenario. Cause: BFD encapsulates packets in insert mode. The egress address of the Policy can be found through local protection, allowing the BFD session to go up. (TR5) |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
Strict URPF must be disabled on the device that sends echo packets to ensure that BFD echo can take effect. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
Both BFD and OAM cannot be configured for the same tunnel link. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
In the scenario where SBFD monitors the segment list of an SRv6 TE Policy, SBFD packets may be forwarded to the egress based on the endpoint address, the SBFD session is up, but service traffic may be interrupted in either of the following situations: 1. The SID stack of the segment list does not include the SID of the egress. 2. The encapsulation mode of the SRv6 TE Policy is Insert, and TE FRR is enabled. You are advised to plan the SID stack properly for an SRv6 TE Policy . |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
A TTL value is set for checking the BFD session with a specified BGP peer using the peer { <group-name> | <ipv4-address> | <ipv6-address> } bfd valid-ttl-hops command. Because multiple protocols can share a BFD session (for example, BGP can share a BFD session with static routes and IPsec), TTL check takes effect for the shared session. If TTL check fails, session flapping may occur. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
1, U-BFD for SRv6 TE Policy list must be used together with the BFD no-bypass function. 2, Because the source and destination IPv6 addresses of U-BFD packets are the same, URPF cannot be deployed on the egress. Otherwise, BFD packets will be discarded. 3, The egress does not verify the discriminators in BFD packets. When the SID stack configuration is incorrect, the U-BFD session for SRv6 TE Policy list may incorrectly go up. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
After a static BFD session is configured, if the number of dynamic BFD sessions on the device increases before the commit command is run, the number of static BFD sessions may exceed the maximum number supported by the device after the commit command is run. The excess BFD sessions cannot be negotiated. You are advised to delete BFD sessions to reduce the total number of BFD sessions to be less than the maximum number of BFD sessions supported by the device. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
The forward and reverse paths of a BFD for LSP session must be inconsistent. If the forward and reverse paths of a BFD session are inconsistent and the reverse path fails, the forward LSP may be incorrectly switched. As a result, service traffic is lost. You are advised to Perform configuration according to the configuration requirements. When a BFD for LSP session is deployed on a network, the following requirements must be met: For a dyNonemic BFD for LSP session, configure a route constraint mode to ensure that the forward and reverse paths are consistent (for example, use high-priority static routes). For a static BFD for LSP session (excluding BFD for TE LSP), configure a route constraint mode to ensure that the forward and reverse paths are consistent (for example, use high-priority static routes). For a static BFD for TE LSP session, configure strict explicit path constraints to ensure that the forward and reverse paths are consistent, and configure a BFD for TE LSP session on both the forward and reverse paths. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
BFD for IP tracking interfaces: Only the physical status of interfaces can be tracked, and only physical and Eth-Trunk interfaces are supported. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
When configuring SBFD to monitor the segment list of an SRv6 TE Policy, ensure that the endpoint address of the SRv6 TE Policy is the local IP address of the egress. Otherwise, the SBFD session cannot go up. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
In a BFD for TE-LSP scenario, if the forward primary path overlaps the reverse backup path and the reverse primary path overlaps the forward backup path, the BFD detection result is inaccurate. Once a link shared by the primary and backup LSPs monitored by BFD fails, both BFD sessions that monitor the primary and backup LSPs go Down, causing packet loss due to an incorrect traffic switchover. You are advised to configure the forward and reverse primary paths and the forward and reverse backup paths over the same links. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |
SBFD for SR-TE LSP supports transmission of return traffic over a tunnel (corresponding command: mpls te bfd reverse-label). After this function is enabled, the SBFD session established between a Huawei device and a non-Huawei device may be down. |
NetEngine 8000 F |
NetEngine 8000 F2A/NetEngine 8000 F1A |