Users Guide

VLT physical ports 802.1p, 802.1q, LLDP, ow control, port monitoring, and jumbo frames are supported on VLT physical ports.
System
management
protocols
All system management protocols are supported on VLT ports—SNMP, AAA, ACL, DNS, FTP, SSH, system log,
NTP, RADIUS, SCP, and LLDP.
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, RPVST+, and MSTP.
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 interconnects, 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 Interfaces on VLT peers in the VLT interconnect (VLTi) link.
VLT MAC address Unique MAC address that you assign to the VLT domain. A VLT MAC address is a common address in both VLT
peers. 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 both 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 port channel interfaces on both peers that you bundle together.
Orphan ports Ports that are not part of the VLT port channel but members of the spanned VLANs. The term spanned VLAN
refers to a VLAN that is congured on both the VLT peers.
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. IPv6 addressing is used on this control VLAN for VLT peer-
to-peer communication.
• ARP, IPv6 neighbors, and MAC tables synchronize between the VLT peer nodes.
• VLT peer devices operate as separate nodes 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.
1196
Virtual Link Trunking