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.

Other related questions:
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.

Layer 2 multicast entries and usage of S series switches
For an S series switch, entries fall into protocol and forwarding entries. Protocol entries include router port entries and host port entries. You can run the display igmp-snooping router-port command to check router port entries, run the display igmp-snooping port-info command to check host port entries, and run the display l2-multicast forwarding-table command to check forwarding entries. Protocol entries are triggered by protocol packets or manually generated. They are used to identify the protocol exchange status. Forwarding entries are generated based on protocol entries and are used to guide subsequent multicast data forwarding.

Why is no Layer 3 multicast forwarding entry generated on S series switches after users order multicast programs
The possible causes are as follows: - No RP is configured on the PIM-SM network. In this case, configure static or dynamic RP. - The route to the multicast source or RP is unreachable. In this case, configure a unicast routing protocol to enable the switch to learn the routes to the multicast source or RP.

Do S series switches support the Layer 3 multicast function
To achieve multicast forwarding of video services on Layer 3 networks, you need to configure the Layer 3 multicast function on switches. The Layer 3 multicast function requires two multicast protocols as follows: - Internet Group Management Protocol (IGMP): It is used to establish and maintain multicast group memberships between receiver hosts and directly connected multicast routers. - Protocol Independent Multicast (PIM): It is used to obtain multicast requirements of receiver hosts, generate multicast routing entries, and set up multicast forwarding paths. IGMP and PIM are supported by Huawei S series modular switches, and Sx7 series fixed switches including the S3700EI, S3700HI, S5700EI, S5710EI, S5720EI, S5700HI, S5710HI, S5720SI, S5720S-SI, S5720HI, S6700EI, S6720EI and S6720S-EI.

Why does a Layer 3 multicast forwarding entry contain a loopback inbound interface
When the source IP address of multicast data packets is the same as the IP address of the VLANIF interface on the source DR, the corresponding Layer 3 multicast forwarding entry contains a loopback inbound interface. To solve this problem, change the source IP address of multicast data packets. Ensure that the source IP address is on the same network segment as the IP address of VLANIF interface, but is different from the IP address of VLANIF interface.

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