and the VLAN is a primary VLT VLAN on one peer and not a primary VLT VLAN on the other peer, MACsynchronization does not occur.Whenever a change occurs in the VLAN mode of one of the peers, this modification is synchronized withthe other peers. Depending on the validation mechanism that is initiated for MAC synchronization of VLTpeers, MAC addresses learned on a particular VLAN are either synchronized with the other peers, or MACaddresses synchronized from the other peers on the same VLAN are deleted. This method of processingoccurs when the PVLAN mode of VLT LAGs is modified.Because the VLTi link is only a member of symmetric VLT PVLANs, MAC synchronization takes placedirectly based on the membership of the VLTi link in a VLAN and the VLT LAG mode.PVLAN Operations When One VLT Peer is DownWhen a VLT port moves to the Admin or Operationally Down state on only one of the VLT nodes, the VLTLag is still considered to be up. All the PVLAN MAC entries that correspond to the operationally down VLTLAG are maintained as synchronized entries in the device. These MAC entries are removed when the peerVLT LAG also becomes inactive or a change in PVLAN configuration occurs.PVLAN Operations When a VLT Peer is RestartedWhen the VLT peer node is rebooted, the VLAN membership of the VLTi link is preserved and when thepeer node comes back online, a verification is performed with the newly received PVLAN configurationfrom the peer. If any differences are identified, the VLTi link is either added or removed from the VLAN.When the peer node restarts and returns online, all the PVLAN configurations are exchanged across thepeers. Based on the information received from the peer, a bulk synchronization of MAC addresses thatbelong to spanned PVLANs is performed.During the booting phase or when the ICL link attempts to come up, a system logging message isrecorded if VLT PVLAN mismatches, PVLAN mode mismatches, PVLAN association mismatches, or PVLANport mode mismatches occur. Also, you can view these discrepancies if any occur by using the showvlt mismatch command.Interoperation of VLT Nodes in a PVLAN with ARP RequestsWhen an ARP request is received, and the following conditions are applicable, the IP stack performscertain operations.• The VLAN on which the ARP request is received is a secondary VLAN (community or isolated VLAN).• Layer 3 communication between secondary VLANs in a private VLAN is enabled by using the iplocal-proxy-arp command in INTERFACE VLAN configuration mode.• The ARP request is not received on the ICLUnder such conditions, the IP stack performs the following operations:• The ARP reply is sent with the MAC address of the primary VLAN.• The ARP request packet originates on the primary VLAN for the intended destination IP address.The ARP request received on ICLs are not proxied, even if they are received with a secondary VLAN tag.This behavior change occurs because the node from which the ARP request was forwarded would havereplied with its MAC address, and the current node discards the ARP request.964 Virtual Link Trunking (VLT)
