Concept Guide

l When no uplink is enforced and preemption is not enabled, and if the current uplink fails, the W-IAP tries to
find an available uplink based on the priority configured.
Uplink Preemption
When no uplink is enforced and preemption is enabled, and if the current uplink fails, the W-IAP tries to find an
available uplink based on in the priority configured. If current uplink is active, the W-IAP periodically tries to use
a higher priority uplink and switches to the higher priority uplink even if the current uplink is active.
Uplink Priority
When uplink priority is configured, the W-IAP tries to get a higher priority link every ten minutes even if the
current uplink is up. This does not affect the current uplink connection. If the higher uplink is usable, the W-IAP
switches over to that uplink. Preemption is enabled by default.
Uplink Switchover
The default priority for uplink switchover is Ethernet and then 3G/4G. The W-IAP has the ability to switch to the
lower priority uplink if the current uplink is down.
Uplink Switching based on VPN Status
Instant supports switching uplinks based on the VPN status when deploying mixed uplinks (Eth0, 3G/4G,Wi-Fi).
When VPN is used with multiple backhaul options, the W-IAP switches to an uplink connection based on the
VPN connection status instead of only using Eth0, the physical backhaul link.
The following configuration conditions apply to uplink switching:
l If the current uplink is Eth0 and the VPN connection is down, the W-IAP will retry to connect to VPN. This
retry time depends on the configuration of primary/backup and fast-failover for VPN. If all the possibilities
fail, then the W-IAP waits for a vpn-failover-timeout and then a different u plink (3G,Wi-Fi) is selected.
l If the current uplink is 3G or Wi-Fi, and Eth0 has a physical link, the W-IAP periodically suspends user traffic
to try and connect to the VPN on the Eth0. If the W-IAP succeeds, then the W-IAP switches to Eth0. If the W-
IAP does not succeed, then the W-IAP restores the VPN connection to the current uplink.
Switching Uplinks Based on Internet Availability
When the uplink switchover based on Internet availability is enabled, the W-IAP continuously sends ICMP
packets to some well-known Internet servers. If the request is timed out due to a bad uplink connection or
uplink interface failure, and the public Internet is not reachable from the current uplink, the W-IAP switches to a
different connection.
Example
The following example configures uplink priority:
(Instant AP)(uplink)# uplink-priority ethernet port 0 1
(Instant AP)(uplink)# end
(Instant AP)# commit apply
Dell Networking W-Series Instant 6.4.3.1-4.2.0.0 | CLI Reference Guide uplink | 559