How does an S series switch process unknown multicast flows

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Unknown multicast flows are the multicast data flows that have no forwarding entries in the chip or the flows that are not requested by users. When Layer 2 multicast is not enabled on a switch, an S series switch broadcasts unknown multicast flows in a VLAN. After Layer 2 multicast is enabled, processing on other models excluding the S1700 is as follows:

If Layer 2 multicast is enabled on the E600, S1720, S2700SI, S2710SI, S2700EI, S2720, S2750EI, S5700S-LI, S5700LI, S5710-C-LI, S5710-X-LI, S5700SI, S5720S-SI, and S5720SI, they broadcast unknown multicast flows in the corresponding VLAN, regardless of which Layer 2 multicast forwarding mode is used.
- Other switches process unknown multicast flows based on the Layer 2 multicast forwarding mode. If the IP address-based forwarding mode is used, the switches drop unknown multicast flows. If the MAC address-based forwarding mode is used, the switches broadcast unknown multicast flows in a VLAN.

To prevent broadcast of unknown multicast packets in a VLAN, run the multicast drop-unknown command. This command configures a switch to drop unknown multicast packets. After this command is configured, the switch also discards protocol packets that are transparently transmitted within the VLAN and use the reserved multicast address.

Other related questions:
How does an S series switch process UDP packets when it functions as a Layer 2 switch
If an S series switch (except the S1700) functions as a Layer 2 switch, it does not identify UDP or TCP packets by default. The switch only forwards packets based on its original MAC address table.

How does an S series switch process packets when Layer 2 multicast references an ACL
In Layer 2 multicast, three functions need to reference the ACL. After an ACL is referenced, packets are processed based on ACL rules. If no rule is configured, packets are processed as follows: - IGMP snooping group policy: In V200R001 and earlier versions, the default rule is permit. In V200R002 and later versions, if default-permit is not configured, the default rule is deny; if default-permit is configured, the default rule is permit. - IGMP snooping prompt leave: In V200R001 and earlier versions, the default rule is permit. In V200R002 and later versions, if default-permit is not configured, the default rule is deny; if default-permit is configured, the default rule is permit. - IGMP snooping SSM policy: The default rule is deny.

How to configure flow shaping on S series switch
S series switch (except S1700) switch, traffic shaping is to control the speed of the output message, so that the message sent at a uniform rate. It can be achieved through the flow of the function of the port speed limit. There is no difference of Traffic shaping configuration between frame type equipment and S series switch box equipment. Configuration example is as following. [HUAWEI] interface gigabitethernet 3/0/1 [HUAWEI-GigabitEthernet3/0/1] qos queue 0 shaping cir 50000 pir 100000 Notice: - On S series switch box equipment, S5720HI does not support CIR, CBS and PBS configuration parameters. - S series switch box X1E series of devices do not support the configuration of CIR, CBS and PBS parameters.

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.

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