T1 gateway connection on the source NSX Segment remains active after HCX Unextend Network task is completed

Products

• VMware HCX

Issue/Introduction

• Removing a Network Extension task initiated for Extended Network where source network is NSX Segment.
• Removing a Network Extension has completed successfully with "Connect cloud network to cloud edge gateway after unextending" selected and on completion, Cloud NSX Segment is connected to T1 gateway successfully but T1 gateway connection on the source for the source NSX Segment remains active.

Resolution

• It is expected behavior, HCX does not disconnect onprem gateway during the Removing a Network Extension workflow. It is a user responsibility to perform a gateway cutover and make sure that the gateway is disabled on premises whether it is physical router or NSX Edge gateway. HCX provides an option to connect the gateway on destination as destination extended network can only be NSX Segment. There are no workflows in HCX that configure gateway on-premises.
  
  
• When selecting the "Connect cloud network to cloud edge gateway after unextending" option during Removing a Network Extension task, there is a warning which warns about the routing loop when Cloud NSX Segment is connected to T1 gateway:   Removing a Network Extension
  
  "(Optional) For each network that will be unextended, expand the network entry and select Connect cloud network to cloud edge gateway after unextending to connect the remote side gateway.
  Dynamic routing can be activated on the Cloud Edge Gateway as part of the OSPF or the BGP configuration. By default, the cloud segment is left disconnected from the Edge Gateway after removing the network extension. This is done to prevent an Edge Gateway from advertising a route to the cloud segment and causing a potential routing conflict with the network in the on-premises data center. Selecting this option connects the segment to the Cloud Edge Gateway after removing the network extension. If dynamic routing is activated, the network is advertised from the Cloud Edge Gateway."