Administrator Guide

The association of PVLAN with the VLT LAG must also be identical. After the VLT LAG is congured to be a member of either the primary
or secondary PVLAN (which is associated with the primary), ICL becomes an automatic member of that PVLAN on both switches. This
association helps the PVLAN data ow received on one VLT peer for a VLT LAG to be transmitted on that VLT LAG from the peer.
You can associate either a VLT VLAN or a VLT LAG to a PVLAN. First congure the VLT interconnect (VLTi) or a VLT LAG by using the
peer-link port-channel id-number command or the VLT VLAN by using the peer-link port-channel id-number
peer-down-vlan vlan interface number command and the switchport command. After you specify the VLTi link and VLT
LAGs, you can associate the same port channel or LAG bundle that is a part of a VLT to a PVLAN by using the
interface interface
and switchport mode private-vlan commands.
When a VLTi port in trunk mode is a member of symmetric VLT PVLANs, the PVLAN packets are forwarded only if the PVLAN settings of
both the VLT nodes are identical. You can congure the VLTi in trunk mode to be a member of non-VLT PVLANs if the VLTi is congured
on both the peers. MAC address synchronization is performed for VLT PVLANs across peers in a VLT domain.
Keep the following points in mind when you congure VLT nodes in a PVLAN:
• Congure the VLTi link to be in trunk mode. Do not congure the VLTi link to be in access or promiscuous mode.
• You can congure a VLT LAG or port channel to be in trunk, access, or promiscuous port modes when you include the VLT LAG in a
PVLAN. The VLT LAG settings must be the same on both the peers. If you congure a VLT LAG as a trunk port, you can associate that
LAG to be a member of a normal VLAN or a PVLAN. If you congure a VLT LAG to be a promiscuous port, you can congure that LAG
to be a member of PVLAN only. If you congure a VLT LAG to be in access port mode, you can add that LAG to be a member of the
secondary VLAN only.
• ARP entries are synchronized even when a mismatch occurs in the PVLAN mode of a VLT LAG.
Any VLAN that contains at least one VLT port as a member is treated as a VLT VLAN. You can congure a VLT VLAN to be a primary,
secondary, or a normal VLAN. However, the VLT VLAN conguration must be symmetrical across peers. If the VLT LAG is tagged to any
one of the primary or secondary VLANs of a PVLAN, then both the primary and secondary VLANs are considered as VLT VLANs.
If you add an ICL or VLTi link as a member of a primary VLAN, the ICL becomes a part of the primary VLAN and its associated secondary
VLANs, similar to the behavior for normal trunk ports. VLAN parity is not validated if you associate an ICL to a PVLAN. Similarly, if you
dissociate an ICL from a PVLAN, although the PVLAN parity exists, ICL is removed from that PVLAN.
Association of VLTi as a Member of a PVLAN
If a VLAN is congured as a non-VLT VLAN on both the peers, the VLTi link is made a member of that VLAN if the VLTi link is congured as
a PVLAN or normal VLAN on both the peers. If a PVLAN is congured as a VLT VLAN on one peer and a non-VLT VLAN on another peer,
the VLTi is added as a member of that VLAN by verifying the PVLAN parity on both the peers. In such a case, if a PVLAN is present as a
VLT PVLAN on at least one of the peers, then symmetric conguration of the PVLAN is validated to cause the VLTi to be a member of that
VLAN. Whenever a change in the VLAN mode on one of the peers occurs, the information is synchronized with the other peer and VLTi is
either added or removed from the VLAN based on the validation of the VLAN parity.
For VLT VLANs, the association between primary VLAN and secondary VLANs is examined on both the peers. Only if the association is
identical on both the peers, VLTi is congured as a member of those VLANs. This behavior is because of security functionalities in a
PVLAN. For example, if a VLAN is a primary VLT VLAN on one peer and not a primary VLT VLAN on the other peer, VLTi is not made a part
of that VLAN.
MAC Synchronization for VLT Nodes in a PVLAN
For the MAC addresses that are learned on non-VLT ports, MAC address synchronization is performed with the other peer if the VLTi (ICL)
link is part of the same VLAN as the non-VLT port. For MAC addresses that are learned on VLT ports, the VLT LAG mode of operation and
the primary to secondary association of the VLT nodes is determined on both the VLT peers. MAC synchronization is performed for the
VLT LAGs only if the VLT LAG and primary-secondary VLT peer mapping are symmetrical.
Virtual Link Trunking (VLT)
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