What are the precautions for configuring multicast BFD


The BFD packets sent in multicast mode are untagged.

When a port configured with multicast BFD receives tagged packets, it checks the tag of the packets. If the tag is different from the port's default VLAN ID, the port discards the packets.

To configure multicast BFD on an interface, run the port default vlan command to specify the default VLAN of the interface.

Other related questions:
What is the function of the default multicast address of BFD on an AR
When BFD is used to detect the physical status of a link, you may not specify the remote IP address. In some situations, the remote end such as the Eth-Trunk member link is not assigned an IP address. A BFD session needs to be bound to a multicast IP address and the AR needs to send BFD control packets to the multicast IP address. In the following situations, you must change the default multicast IP address: - On the network, other protocols use the multicast IP address. - Multiple BFD sessions exist on the BFD detection path. For example, when Layer 3 interfaces are connected through Layer 2 switching devices that support BFD, you must configure different default multicast IP addresses for the devices where different BFD sessions are established. You can run the default-ip-address ip-address command to configure the default multicast IP address for the BFD session. [Huawei] bfd [Huawei-bfd] default-ip-address //Set the default multicast address bound to the BFD session to

What are the precautions for deploying multicast VLAN replication on a ring network
A multicast VLAN is the user VLAN of itself by default, so you do not need to run the multicast user-vlan command. When configuring multicast VLAN replication on the S1720, S2700, S5700S-LI (except S5700S-28X-LI-AC and S5700S-52X-LI-AC), or S5700LI, pay attention to the following constraints: -A user-side interface can be added to only one user VLAN. If the interface is added to multiple user VLANs, the user VLAN where multicast entries are generated first takes effect. -The user-side interface also needs to be added to the multicast VLAN in the same mode as it is added to the user VLAN. For example, if the user-side interface is added to the user VLAN in untagged mode, it must be added to the multicast VLAN in untagged mode. -To prevent broadcast of unknown multicast packets, enable the switch to drop unknown multicast packets. On the S2700SI or S2700EI, run the multicast drop-unknown command in the system view to enable this function. On the S1720, S2720, S5700S-LI or S5700LI, run the multicast drop-unknown command in the VLAN view to enable this function.

What are precautions for configuring static RP in Layer 3 multicast application
When only one RP exists on the network, you can configure a static RP rather than using a dynamic RP. This reduces bandwidth occupied by messages exchanged between the candidate rendezvous point (C-RP) and the bootstrap router (BSR). Pay attention to the following when configuring a static RP: 1.The same static-rp command must be used on all the switches in the PIM-SM domain. 2.If the preferred keyword is not used when you configure the static RP, the switch prefers the dynamic RP elected through the BSR mechanism. The switch prefers the static RP only when you specify the preferred keyword in the static-rp command. 3.If multiple static RPs are available for a multicast group, the RP with the largest IP address serves the group. 4.If an ACL is specified in the command, the static RP serves only the groups permitted by the ACL.

Precautions for the configuration of multicast BFD sessions on S series switches
For S series switches, the packets sent by multicast BFD are untagged. When a BFD interface receives a tagged BFD packet, the BFD module checks whether the VLAN ID of the BFD packet is the same as the default VLAN ID on the interface. If not, the BFD module discards the packet. To configure multicast BFD on an interface, run the port default vlan command to specify the default VLAN of the interface.

What is BFD
Bidirectional Forwarding Detection (BFD) quickly detects communications faults between systems and reports corresponding faults to the upper-layer protocol.

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