Connectivity Guide

Multicast IGMP snooping and MLD snooping are supported on VLT ports.
NOTE: 802.1x and DHCP snooping are not supported on VLT ports.
Terminology
VLT domain The domain includes VLT peer devices, VLT interconnect, and all port-channels in the VLT connected
to the attached devices. It is also the configuration mode that you must use to assign VLT global
parameters.
VLT interconnect
(VLTi)
The link between VLT peer switches used to synchronize operating states.
VLT peer device A pair of devices connected using a dedicated port-channel — the VLTi. You must configure VLT peers
separately.
Discovery
interface
Port interfaces on VLT peers in the VLT interconnect (VLTi) link.
VLT MAC address (Optional) Unique MAC address that you assign to the VLT domain. A VLT MAC address is the common
address all VLT peers use. If you do not configure a VLT MAC address, the MAC address of the primary
peer is used as the VLT MAC address across all peers.
VLT node priority The priority based on which the primary and secondary VLT nodes are determined. If priority is not
configured, the VLT node with the lowest MAC address is elected as the primary VLT node.
VLT port-channel A combined port-channel between an attached device and VLT peer switches.
VLT port-channel
ID
Groups port-channel interfaces on VLT peers into a single virtual-link trunk connected to an attached
device. Assign the same port-channel ID to interfaces on different peers that you bundle together.
Orphan ports Ports that are connected to VLT domain, but not part of the VLT-LAG.
VLT domain
A VLT domain includes the VLT peer devices, VLTi, and all VLT port-channels that connect to the attached devices. It is also the
configuration mode that you must use to assign VLT global parameters.
● Each VLT domain must have a unique MAC address that you create or that VLT creates automatically.
● VLAN ID 4094 is reserved as an internal control VLAN for the VLT domain.
● ARP, IPv6 neighbors, and MAC tables synchronize between the VLT peer nodes.
● VLT peer devices operate as a separate node with independent control and data planes for devices that attach to non-VLT
ports.
● One node in the VLT domain takes a primary role and the other node takes the secondary role. In a VLT domain with two
nodes, the VLT assigns the primary node role to the node with the lowest MAC address by default. You can override the
default primary election mechanism by assigning priorities to each node using the primary-priority command.
● If the primary peer fails, the secondary peer (with the higher priority) takes the primary role. If the primary peer (with the
lower priority) later comes back online, it is assigned the secondary role (there is no preemption).
● In a VLT domain, the peer network devices must run the same OS10 software version.
● Configure the same VLT domain ID on peer devices. If a VLT domain ID mismatch occurs on VLT peers, the VLTi does not
activate.
● In a VLT domain, VLT peers support connections to network devices that connect to only one peer.
VLT interconnect
A VLT interconnect (VLTi) synchronizes states between VLT peers. OS10 automatically adds VLTi ports to VLANs spanned
across VLT peers and does not add VLTi ports to VLANs configured on only one peer.
● VLAN ID 4094 is reserved as an internal control VLAN for the VLT domain, and it is not user configurable.
● The VLTi synchronizes L2 and L3 control-plane information across the two nodes. The VLTi is used for data traffic only
when there is a link failure that requires VLTi to reach the final destination.
Virtual Link Trunking
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