Some FAQs about Huawei S2700 S3700 S5700 S6700 Switch

Many engineer always confused Huawei switch when configuration and management, below are FAQs about Huawei S2700 S3700 S5700 S6700 Switch,

What Are the Functions of PIM Silent on a PIM Interface?

On the access layer, if the interface directly connected to a host is enabled with the PIM
protocol, PIM neighbors can be established on this interface to process various PIM protocol
packets. Such configuration, however, may bring security problems. For example, when
malicious hosts send a large number of pseudo PIM Hello packets, it may lead to the collapse
of the device.
To avoid the preceding problem, you can run the pim silent command on the interface to set
the interface to work in PIM silent state. After the interface enters the PIM silent state, it is
forbidden to receive or forward any PIM protocol packet. All PIM neighbors and the PIM
state machine on this interface are deleted and the interface automatically becomes a DR.
Meanwhile, the PIM silent function does not affect the IGMP function on the interface.
The PIM silent function is applicable only to the interface that is directly connected to the
network segment of user hosts, and only one PIM device can be connected to this network
segment.

When a Host Leaves a Group, How Does an IGMP Querier Judge Whether Any Other Members of the Group Exist on the Network Segment?

In IGMPv1, when a host leaves a multicast group, the host does not send any message. A
device considers that all multicast members have left a group when the timer of the group
expires.
In IGMPv2 and IGMPv3, a host sends a Leave message when leaving a group. After
receiving the Leave message, the querier sends a group-specific or source/group-specific
Query message to the network segment of the host. The destination address of the Query
message is the address of the multicast group and the group address in the message is also
filled in with the address of the multicast group.
If other members of the group exist on the network segment, they respond with Report
messages.
If no response is received when the timeout period ends, the querier considers that no
member of the group exists on the network segment and cancels forwarding multicast

data to the group.

Can the Hosts and Devices on the Same User Network Segment Run Different Versions of IGMP?

IGMP has three versions, namely IGMPv1, IGMPv2, and IGMPv3. Different IGMP versions
run on devices and hosts are compatible, but all the devices on the same network segment
must run IGMP of the same version. If the versions of IGMP run on the devices on the same
network segment are different, IGMP member relationships are chaotic.
Run the display igmp interface interface-type interface-number command on all the devices
on the same network segment to check the versions of IGMP run on the devices. If the
versions are not the same, modify the configuration.

Other questions about Huawei switch will be posted continually.