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Microsoft Azure pros share their latest insights on verifying BGP routes, controlled IaaS VM costs, the implications of bursting on Premium SSD disks and more.
Verifying BGP routes
Aidan Finn explained the importance of verifying ExpressRoute communications to make sure that traffic is reaching on-prem or WAN subnets after correctly propagating by BGP. He wrote:
Routing to Azure is often easy; your network admins allocate you a block of private address space on the “WAN” and you use it for your virtual network(s). They add a route entry to that CIDR block on their VPN/ExpressRoute edge device and packets can now get to Azure. The other part of that story is that Azure needs to know how to send packets back to on-premises – this affects responses and requests. And I have found that this is often overlooked and people start saying things like “Azure networking is broken” when they haven’t sent a route to Azure so that the Azure resources connected to the virtual network(s) can respond.
With this in-mind, Finn showed how to use PowerShell to find routes, cautioning that it doesn’t support CSV formats by default. He added that Azure portal also offers ways to track routes. Users can open the Route Table Summary in Private Peering to inspect routing.