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Can I install a route server without an outage?

adm_Enzo Smeriglio 0 Reputation points
2026-02-18T10:50:46.7966667+00:00

I see conflicting information

I need to deploy a route server into an existing vnet.

I have Express route -primary line to on prem

I have VPN route - secondary line to on prem

I have 1 NVA firewall (its ok if this one has an outage during deployment)

Azure Route Server
Azure Route Server

An Azure service that enables network appliances to exchange route information with Azure virtual networks dynamically.

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  1. Ravi Varma Mudduluru 7,575 Reputation points Microsoft External Staff Moderator
    2026-02-18T11:09:08.4633333+00:00

    Hello @ adm_Enzo Smeriglio,

    Thanks for reaching out to Microsoft of Q&A.

    I see you're looking to deploy a route server into your existing VNet without incurring an outage. Unfortunately, here’s the info you need to know: when a Route Server is created or deleted in a virtual network that includes a virtual network gateway (like ExpressRoute or VPN), there will be a brief downtime expected to last around 10 minutes. It's also recommended to plan for a maintenance window of about 60 minutes for the entire deployment process.

    Here's what I suggest:

    • Schedule Your Deployment: Given the expected downtime, pick a maintenance window when network traffic is at its lowest.
    • Prepare Your Environment:
      • Ensure the subnet for the Route Server is at least /26 in size.
      • Check that your NVA is properly configured to BGP peer with both Route Server instances.
    • Follow Best Practices:

    Reference Document:

    If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

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  2. Q&A Assist
    2026-02-18T10:50:57.9233333+00:00
    AI generated content. This question contains an answer created with AI from Q&A Assist. Learn more

    When deploying a Route Server into an existing virtual network that already has an ExpressRoute gateway and/or Azure VPN gateway, there is a period during the deployment when the virtual machines in the virtual network may lose connectivity to the on-premises network. This is due to updates being made to the control plane between the gateways and the virtual network. Therefore, it is strongly recommended to schedule maintenance during the deployment to minimize impact on your operations.

    Since you mentioned that it is acceptable for the NVA firewall to have an outage during deployment, you can proceed with the installation, but be aware that there may be temporary connectivity issues for the other services as well.

    References:

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