Administrator Guide

EXEC mode
Dell# show interfaces port brief
Codes: L - LACP Port-channel
O - OpenFlow Controller Port-channel
LAG Mode Status Uptime Ports
127 L2 up 00:18:22 Fo 0/33 (Up)<<<<<<<<ICL LAG
Fo 0/37 (Up)
L 128 L2 up 00:00:00 Fo 0/41 (Up)<<<<<<<<Uplink LAG
VLT Terminology
The following are key VLT terms.
• Virtual link trunk (VLT) — The combined port channel between an attached device and the VLT peer
switches.
• VLT backup link — The backup link monitors the vitality of VLT peer switches. The backup link sends
configurable, periodic keep alive messages between the VLT peer switches.
• VLT interconnect (VLTi) — The link used to synchronize states between the VLT peer switches.
• VLT domain — This domain includes both the VLT peer devices, VLT interconnect, and all of the port
channels in the VLT connected to the attached devices. It is also associated to the configuration mode
that you must use to assign VLT global parameters.
• VLT peer device — One of a pair of devices that are connected with the special port channel known as
the VLT interconnect (VLTi).
VLT peer switches have independent management planes. A VLT interconnect between the VLT chassis
maintains synchronization of L2/L3 control planes across the two VLT peer switches.
A separate backup link maintains heartbeat messages across an out-of-band (OOB) management network.
The backup link ensures that node failure conditions are correctly detected and are not confused with failures
of the VLT interconnect. VLT ensures that local traffic on a chassis does not traverse the VLTi and takes the
shortest path to the destination via directly attached links.
Configure Virtual Link Trunking
VLT requires that you enable the feature and then configure the same VLT domain, backup link, and VLT
interconnect on both peer switches.
Important Points to Remember
• VLT port channel interfaces must be switch ports.
• Dell Networking strongly recommends that the VLTi (VLT interconnect) be a static LAG and that you
disable LACP on the VLTi.
• If the lacp-ungroup feature is not supported on the ToR, reboot the VLT peers one at a time. After
rebooting, verify that VLTi (ICL) is active before attempting DHCP connectivity.
PMUX Mode of the IO Aggregator 911