Network connectivity drops due to BGP routing issues

Question

Network connectivity drops due to BGP routing issues

Williams Noah 0

Our company's server is experiencing intermittent network connectivity loss, and some internal resources become unreachable. Initial checks suggest that network routes may not be updating correctly after a connection interruption.

How can we inspect the current routing configuration, identify discrepancies between active and backup network paths, and restore stable connectivity? Additionally, what Windows diagnostic tools can help us determine whether the issue is related to network configuration or the server's TCP/IP stack?

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Answer 1

Hello,

Start by comparing the Windows routing table with the expected primary and backup routes using "Get-NetRoute -AddressFamily IPv4 | Sort-Object DestinationPrefix, RouteMetric" and "route print -4" in an elevated PowerShell or Command Prompt. Verify that affected destination prefixes use the correct next-hop addresses and that backup routes remain available. If Windows Server runs Microsoft's RemoteAccess BGP implementation, use "Get-BgpRouter", "Get-BgpPeer", and "Get-BgpRouteInformation" to inspect BGP configuration, peer status, and learned routes. If BGP runs on an external router, check its neighbor status, advertised prefixes, and routing policies instead. Test connectivity using "Test-NetConnection <destination-IP> -Port <port> -InformationLevel Detailed" and trace the path with "tracert -d <destination-IP>". Check "Get-NetAdapter", "Get-NetIPInterface", and "Get-NetNeighbor", along with Windows System event logs, for adapter failures, incorrect interface settings, or TCP/IP errors. If routes remain correct but connectivity fails, investigate firewalls, asymmetric routing, packet loss, DNS resolution, and remote service availability. Avoid running "netsh int ip reset" or "netsh winsock reset" on a production server until you have documented its network configuration and confirmed a local TCP/IP issue. Please confirm whether BGP runs on Windows Server or an external router and specify the Windows Server version to help narrow down the root cause.

I hope you've found something useful here. If it helps you get more insight into the issue, it's appreciated to accept the answer. Should you have more questions, feel free to leave a message. Have a nice day!

HP.