> ## Documentation Index
> Fetch the complete documentation index at: https://docs.aviatrix.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Upgrade HA Gateways in An ActiveMesh Topology
> Gateway traffic is briefly affected and there is a drop in throughput when you perform a gateway image upgrade, and when a gateway software upgrade is rolled back.
## Upgrading HA Gateways in an ActiveMesh Topology
Gateway traffic is briefly affected and there is a drop in throughput when you
perform a gateway image upgrade, and when a gateway software upgrade is rolled
back. If Aviatrix ActiveMesh mode is enabled and only one gateway in an
ActiveMesh pair is selected for upgrade, the system gracefully drains the
traffic away from one of the gateways so it can be replaced. If both gateways in
an ActiveMesh pair are selected, the gateways are replaced simultaneously
without any additional safeguards.
* If the gateway has BGP peers, the BGP process is shut down and the protocol
reconverges to elect alternatives routes.
* The tunnel interfaces are shut down. The Controller recalculates alternatives
routes and distributes them to the gateways within the Aviatrix network.
* If the selected gateway is a spoke, the Controller modifies the underlay cloud
routing table of the selected gateway that was acting as the next hop for the
default route or RFC1918 routes. The HA peer is selected as the next hop.
## Related Topics
* Upgrade OpenVPN Users
* Unattended Upgrades for Controllers and Gateways