Change the aging time for multicast traffic–triggered entries in a VLAN on a CE series switch

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If no multicast data is sent to a multicast group, a CE series switch needs to delete matching (S, G) or (*, G) entries. Therefore, the switch needs to periodically detect multicast flows sent to the multicast group to determine whether to delete the matching entries. You can run the multicast layer-2 source-lifetime lifetime command to set the aging time for multicast traffic–triggered entries in a VLAN. If the switch does not receive any multicast data sent from a multicast source to a multicast group within the aging time, the switch deletes the matching (S, G) or (*, G) entries. The deletion allows the switch to update multicast entries and release entry resources in a timely manner.
By default, the aging time of a multicast traffic–triggered entry in a VLAN is 210 seconds. You can set a proper aging time for multicast traffic–triggered entries according to the number of multicast entries used on your network.
In the following example, the aging time of multicast traffic–triggered entries in VLAN 100 is set to 1000 seconds.

<HUAWEI> system-view
[~HUAWEI] igmp snooping enable
[*HUAWEI] vlan 100
[*HUAWEI-vlan100] igmp snooping enable
[*HUAWEI-vlan100] multicast layer-2 source-lifetime 1000
[*HUAWEI-vlan100] commit

Other related questions:
Aging time of ARP entries on S series switches
For S series switches (except S1700 switches),
the default aging time of dynamic ARP entries is 1200s (20 minutes). You can run the arp expire-time  expire-time command in the system view or an interface view to configure the aging time of dynamic ARP entries. Configure the second expire-time variable as the target aging time of dynamic ARP entries.
Static ARP entries do not age.

What are the aging time and aging mechanism of ARP entries
The default aging time of ARP entries is 20 minutes. You can run the arp expire-time command to change the aging time. You can also change the number of ARP probes by running the arp detect-times command. The default number of ARP probes is 3. When the aging time of an ARP entry expires, the device sends a probe packet to the corresponding IP address every 5 seconds. If the device does not receive any response after the specified number of probes, it deletes the ARP entry. For example, the aging time of ARP entries is set to 60s and the number of ARP probes is set to 6. After 60s since an ARP entry is generated, the device sends an ARP probe every 5s. If the device does not receive any response after sending six probes, it deletes the ARP entry. Therefore, the actual aging time of the ARP entry is (60 + 6 x 5) = 90s. NOTE: For V100R002 version, the S2700/S3700/S5700/S6700 supports the 1/2 probe time and 3/4 probe time. The numbers of probes on the two time points are both 3 and cannot be changed. For example, if the aging time is 20 minutes (1200s) and the number of ARP probes is 6, the SS2700/S3700/S5700/S6700 sends three ARP probes at an interval of 5s after 10 minutes. After 15 minutes, the S2700/S3700/S5700/S6700 also sends three ARP probes at an interval of 5s. After 20 minutes, the S2700/S3700/S5700/S6700 sends six ARP probes at an interval of 5s. If the S2700/S3700/S5700/S6700 does not receive any response, it deletes the ARP entry.

How does an S series switch age Layer 3 multicast entries
PIM deletes a Layer 3 multicast entry when the following conditions are met: - No traffic matches the entry. The multicast FIB management module counts packets matching each Layer 3 multicast entry. If no packet matches an entry within 210 seconds, the multicast FIB management module sends an entry inactive message to the PIM module. - The outbound interface list of the entry does not contain any outbound interface learned from PIM Join messages or PIM Prune messages. The outbound interfaces learned from IGMP on the designated router (DR) do not affect aging of Layer 3 multicast entries. If all the preceding conditions are met, PIM considers the entry invalid and deletes it.

Are dynamic DNS entries aged at intervals of the aging time or using the command
Yes. Run the reset dns dynamic-host command to clear dynamic domain name service (DNS) entries.

Aged ARP entry display on S series switches
On S series switches (except S1700 switches), aged ARP entries cannot be displayed. You can only view the current ARP table.

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