Concept Guide

vlt domain domain-id
The domain ID range is from 1 to 1000.
Configure the same domain ID on the peer switch to allow for common peering. VLT uses the domain ID to automatically
create a VLT MAC address for the domain. If you do not configure the system explicitly, the system mac-address of the
primary will be the VLT MAC address for the domain.
To disable VLT, use the no vlt domain command.
NOTE: Do not use MAC addresses such as “reserved” or “multicast.”
2. Configure the IP address of the management interface on the remote VLT peer to be used as the endpoint of the VLT
backup link for sending out-of-band hello messages.
VLT DOMAIN CONFIGURATION mode
back-up destination {ipv4-address | ipv6-address} [interval seconds] {vrf [management
vrf-name | vrf-name]}
NOTE: If management VRF or any specific VRF is enabled on the system, then use the back-up destination
command with vrf [management vrf-name | vrf-name]
You can optionally specify the time interval used to send hello messages. The range is from 1 to 5 seconds.
3. Configure the port channel to be used as the VLT interconnect between VLT peers in the domain.
VLT DOMAIN CONFIGURATION mode
peer-link port-channel id-number
4. Enable peer routing.
VLT DOMAIN CONFIGURATION mode
peer-routing
If you enable peer routing, a VLT node acts as the proxy gateway for its peer.
5. (Optional) After you configure a VLT domain on each peer switch and connect (cable) the two VLT peers on each side of
the VLT interconnect, the system elects a primary and secondary VLT peer device (see Primary and Secondary VLT Peers).
To configure the primary and secondary roles before the election process, use the primary-priority command. Enter a
lower value on the primary peer and a higher value on the secondary peer.
VLT DOMAIN CONFIGURATION mode
primary-priority value
The priority values are from 1 to 65535. The default is 32768.
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).
6. (Optional) Prevent a possible loop during the bootup of a VLT peer switch or a device that accesses the VLT domain.
CONFIGURATION mode
lacp ungroup member-independent {vlt | port-channel port-channel-id}
LACP on VLT ports (on a VLT switch or access device), which are members of the virtual link trunk, is not brought up until
the VLT domain is recognized on the access device.
7. Repeat Steps 1 to 5 on the VLT peer switch to configure the IP address of this switch as the endpoint of the VLT backup
link and to configure the same port channel for the VLT interconnect.
Configuring a VLT Backup Link
To configure a VLT backup link, use the following command.
1. Specify the management interface to be used for the backup link through an out-of-band management network.
CONFIGURATION mode
interface managementethernet slot/port
Enter the slot (0-1) and the port (0).
2. Configure an IPv4 address (A.B.C.D) or IPv6 address (X:X:X:X::X) and mask (/x) on the interface.
MANAGEMENT INTERFACE mode
{ip address ipv4-address/ mask | ipv6 address ipv6-address/ mask}
Virtual Link Trunking (VLT)
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