Reference Guide

with the lowest system MAC address. 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.
VLT interconnect
A VLTi is the link that synchronizes states between VLT peers. OS10 automatically adds VLTi ports to VLANs spanned across VLT peers.
VLTi ports are not supported as members of VLANs congured on only one peer.
• The system automatically provisions the required VLANs.
• VLAN ID 4094 is reserved as an internal control VLAN for the VLT domain, and it is not user congurable.
• VLT peer switches operate as separate nodes with independent control and data planes for devices attached to non-VLT ports.
• The VLTi synchronizes L2 and L3 control-plane information across the two nodes. The VLTi is used for data trac only when there is a
link failure that requires using VLTi for data packets to reach their nal destination.
• Trac with an unknown destination MAC address, multicast, or broadcast trac can cause ooding across the VLTi.
• MAC, ARP, IPv6 neighbors that are learned over VLANs across VLT peer nodes are synchronized across the nodes.
• In a VLT domain, LLDP, ow control, port monitoring, and jumbo frame features are supported on a VLTi.
Congure VLT
Verify that both VLT peer devices are running the same software version. For VRRP operation, congure VRRP groups and L3 routing on
each VLT peer. To congure VLT and create a VLT domain where two devices are physically connected and provide a single port-channel
connection to access devices, congure settings on each VLT peer device.
1 To prevent loops in VLT domain, enable the STP globally (spanning-tree mode {rstp | rapid-pvst} command). RSTP
and RPVST+ modes are supported on VLT ports.
2 Create a VLT domain by conguring the same domain ID on each peer (vlt-domain command).
3 (Optional) To override the default VLT primary election mechanism based on the system MAC addresses of the VLT nodes, congure
a VLT node priority for each of the VLT nodes using the primary-priority command. Enter a lower priority value for the desired
primary VLT peer and a higher priority value for the desired secondary VLT peer.
4 Congure the VLT interconnect interfaces on each peer (discovery-interface command). After you congure both sides of
the VLTi, the primary and secondary roles in the VLT domain are automatically assigned if primary priority is not congured.
5 (Optional) Manually recongure the default VLT MAC address. Congure the VLT MAC address in both the VLT peers.
6 (Optional) Congure a time interval to delay bringing up VLT ports after reload or peer-link restoration between the VLT peer
switches.
7 Congure the VLT backup link used for heartbeat timers (backup destination {ip-address | ipv6 ipv6–address }
[vrf management] [interval interval-time] command).
8 Congure VLT port-channels between VLT peers and an attached device (vlt-port-channel command). Assign the same VLT
port-channel ID from 1 to 1024 to interfaces on dierent peers that you bundle together so that peer interfaces appear as a single VLT
LAG to downstream devices.
9 Connect peer devices in a VLT domain to an attached access device or server.
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Virtual Link Trunking