Install Guide

Reconfiguring Stacked Switches as VLT
To convert switches that have been stacked to VLT peers, use the following procedure.
1. Remove the current configuration from the switches. You will need to split the configuration up for each switch.
2. Copy the files to the flash memory of the appropriate switch.
3. Copy the files on the flash drive to the startup-config.
4. Reset the stacking ports to user ports for both switches.
5. Reload the stack and confirm the new configurations have been applied.
6. On the Secondary switch (stack-unit 2), enter the command stack-unit 2 renumber 1.
7. Confirm the reload query.
8. After reloading, confirm that VLT is enabled.
9. Confirm that the management ports are interconnected or connected to a switch that can transfer Heartbeat information.
Specifying VLT Nodes in a PVLAN
You can configure VLT peer nodes in a private VLAN (PVLAN). VLT enables redundancy without the implementation of
Spanning Tree Protocol (STP), and provides a loop-free network with optimal bandwidth utilization.
Because the VLT LAG interfaces are terminated on two different nodes, PVLAN configuration of VLT VLANs and VLT LAGs
are symmetrical and identical on both the VLT peers. PVLANs provide Layer 2 isolation between ports within the same VLAN.
A PVLAN partitions a traditional VLAN into sub-domains identified by a primary and secondary VLAN pair. With VLT being a
Layer 2 redundancy mechanism, support for configuration of VLT nodes in a PVLAN enables Layer 2 security functionalities. To
achieve maximum VLT resiliency, you should configure the PVLAN IDs and mappings to be identical on both the VLT peer nodes.
The association of PVLAN with the VLT LAG must also be identical. After the VLT LAG is configured to be a member of either
the primary or secondary PVLAN (which is associated with the primary), ICL becomes an automatic member of that PVLAN on
both switches. This association helps the PVLAN data flow received on one VLT peer for a VLT LAG to be transmitted on that
VLT LAG from the peer.
You can associate either a VLT VLAN or a VLT LAG to a PVLAN. First configure the VLT interconnect (VLTi) or a VLT LAG by
using the peer-link port-channel id-number command or the VLT VLAN by using the peer-link port-channel
id-number peer-down-vlan vlan interface number command and the switchport command. After you specify
the VLTi link and VLT LAGs, you can associate the same port channel or LAG bundle that is a part of a VLT to a PVLAN by using
the interface interface and switchport mode private-vlan commands.
When a VLTi port in trunk mode is a member of symmetric VLT PVLANs, the PVLAN packets are forwarded only if the PVLAN
settings of both the VLT nodes are identical. You can configure the VLTi in trunk mode to be a member of non-VLT PVLANs
if the VLTi is configured on both the peers. MAC address synchronization is performed for VLT PVLANs across peers in a VLT
domain.
Keep the following points in mind when you configure VLT nodes in a PVLAN:
● Configure the VLTi link to be in trunk mode. Do not configure the VLTi link to be in access or promiscuous mode.
● You can configure a VLT LAG or port channel to be in trunk, access, or promiscuous port modes when you include the VLT
LAG in a PVLAN. The VLT LAG settings must be the same on both the peers. If you configure a VLT LAG as a trunk port, you
can associate that LAG to be a member of a normal VLAN or a PVLAN. If you configure a VLT LAG to be a promiscuous port,
you can configure that LAG to be a member of PVLAN only. If you configure a VLT LAG to be in access port mode, you can
add that LAG to be a member of the secondary VLAN only.
● ARP entries are synchronized even when a mismatch occurs in the PVLAN mode of a VLT LAG.
Any VLAN that contains at least one VLT port as a member is treated as a VLT VLAN. You can configure a VLT VLAN to be
a primary, secondary, or a normal VLAN. However, the VLT VLAN configuration must be symmetrical across peers. If the VLT
LAG is tagged to any one of the primary or secondary VLANs of a PVLAN, then both the primary and secondary VLANs are
considered as VLT VLANs.
If you add an ICL or VLTi link as a member of a primary VLAN, the ICL becomes a part of the primary VLAN and its associated
secondary VLANs, similar to the behavior for normal trunk ports. VLAN parity is not validated if you associate an ICL to a
PVLAN. Similarly, if you dissociate an ICL from a PVLAN, although the PVLAN parity exists, ICL is removed from that PVLAN.
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Virtual Link Trunking (VLT)