Connectivity Guide

L3 VLAN
connectivity
Enable L3 VLAN connectivity, VLANs assigned with an IP address, on VLT peers by conguring a VLAN interface
for the same VLAN on both devices.
Optimized
forwarding with
VRRP
To ensure the same behavior on both sides of the VLT nodes, VRRP requires state information coordination. VRRP
Active-Active mode optimizes L3 forwarding over VLT. By default, VRRP Active-Active mode is enabled on all the
VLAN interfaces. VRRP Active-Active mode enables each peer to locally forward L3 packets, resulting in reduced
trac ow between peers over the VLTi link.
Spanning-Tree
Protocol
VLT ports support RSTP and RPVST+.
Multicast IGMP snooping and MLD snooping are supported on VLT ports.
NOTE: 802.1x, DHCP snooping, and MSTP are 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 conguration 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 congure 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 congure 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 congured, 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 dierent 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
conguration 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.
• Congure 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.
Virtual Link Trunking
831