Why do we need BGP in a dual-redundancy scenario?

Question

We would like to know why do we need BGP configured in a dual-redundancy scenario described here https://learn.microsoft.com/en-us/azure/vpn-gateway/vpn-gateway-highlyavailable#dual-redundancy-active-active-vpn-gateways-for-both-azure-and-on-premises-networks

Can we avoid doing it with some on-Prem configuration?

Many thanks in advance.

Answer 1

@Dario Ceballos ,

Welcome to the Microsoft Q&A Platform. Thank you for reaching out & I hope you are doing well.

With Dual-redundancy,

• You are creating 2 LNG each with the IP Addresses of your OnPrem range
• Generally, in the LNG, you can either specify the OnPrem Address range or Enable BGP.
• Now, the VPN Gw will treat the 2 LNG as two individual sites.
• So, if you did not use BGP and just mention the address range - Azure will think that there are 2 sites with same address range (Address space overlap) and it will not let you create a connection to the second LNG (second OnPrem IP)
• To circumvent this, BGP is required for dual-redundancy scenario

Please stick to the recommended best practices and use BGP

Thanks,

Kapil

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