Users Guide

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 traffic flow 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 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
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 configure 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
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 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 configured 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
configuration mode that you must use to assign VLT global parameters.
NOTE:
OS10 switches that belong to the same group and have the same port media type can be part of the same VLT
domain. For example, you can have S5224F-ON and S5248F-ON as part of the same domain. However, switches that
belong to the same group with different port media types cannot be part of the same VLT domain. For example, S4148F-ON
and S4148T-ON cannot be part of the same domain.
● 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.
Virtual Link Trunking
1619