Why Are MAC-VLAN Entries Invalid?

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MAC-VLAN entries are only valid for untagged packets. If MAC-VLAN entries are invalid, check whether incoming packets carry VLAN tags.

Other related questions:
Can an interface on an S series switch learn the MAC address entries in a VLAN if the interface is not added to the VLAN
For S series switches (except the S1700), if an interface is not added to a VLAN, the interface does not learn the MAC address entries in the VLAN.

Why the MAC-VLAN does not take effect
MAC address-based VLANs take effect only to untagged packets. If an MAC address-based VLAN does not take effect, check whether the incoming packets contain VLAN tags.

Why does an ARP entry not contain VLAN information
If an ARP entry does not contain VLAN information, the entry contains information about a Layer 3 interface. If an ARP entry contains VLAN information and the interface in the entry is not a sub-interface, the entry contains information about a Layer 2 interface. Run the display arp command to view ARP entries. For example, the ARP entries in V100R003C00 are as follows: - When an ARP entry contains VLAN information, a VLAN ID is displayed in the VLAN field in the command output. - The ARP entry of which the IP address is 10.1.1.2 and the MAC address is 04f9-388d-e685 is dynamically learned from 10GE1/0/3, the VLAN ID is 101, and the remaining lifetime of the entry is 5 minutes. - The ARP entry of which the IP address is 10.1.1.3 and the MAC address is 0023-0045-0067 is a static entry, the outbound interface is 10GE1/0/3, and the VLAN ID is 101. display arp network 10.1.1.0 24 ARP Entry Types: D - Dynamic, S - Static, I - Interface EXP: Expire-time IP ADDRESS MAC ADDRESS EXP(M) TYPE/VLAN INTERFACE VPN-INSTANCE ------------------------------------------------------------------------------ 10.1.1.3 0023-0045-0067 S/101 10GE1/0/3 10.1.1.1 306b-2079-2205 I Vlanif101 10.1.1.2 04f9-388d-e685 5 D/101 10GE1/0/3 ------------------------------------------------------------------------------ Total:3 Dynamic:1 Static:1 Interface:1 - When only the ARP entry type is displayed in the TYPE/VLAN field, the ARP entry does not contain VLAN information. ARP Entry Types: D - Dynamic, S - Static, I - Interface EXP: Expire-time IP ADDRESS MAC ADDRESS EXP(M) TYPE/VLAN INTERFACE VPN-INSTANCE ------------------------------------------------------------------------------ 172.16.1.3 0023-0045-0069 S 10GE1/0/13 172.16.1.1 306b-2079-2202 I 10GE1/0/13 172.16.1.2 0025-9e95-7c32 3 D 10GE1/0/13 ------------------------------------------------------------------------------ Total:3 Dynamic:1 Static:1 Interface:1

Cause why an AR cannot learn correct MAC address entries
The possible causes are as follows: - The AR does not receive packets because the link is Down, the interface does not join the VLAN, the interface participates in spanning tree calculation and is blocked, or MAC address flapping detection is configured and the interface or MAC address is blocked. - Loops cause MAC address flapping. - The AR is disabled from learning MAC address entries or the sticky MAC function is enabled on the interface. - The number of learned MAC address entries has reached the maximum. - The static or blackhole route is configured.

Why Is one MAC address learned in multiple VLANs on S series switch
On S series switches (except S1700), MAC addresses are learned based on MAC addresses+VLANs. If multiple VLANs receive packets with the same MAC address, these VLANs will learn the same MAC address.

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