In this Scenario,connections from an on-premises computer to a virtual machine (tenant VM) behind a HNV GW, or vice versa, fails intermittently. Not all connections may be affected, especially connections consisting of only small packets might work.
This may happen if the HNV GW is located on Hyper-V host cluster node 1, or on node 2 only, or on both nodes.
Therefore the HNV GW sends an ICMP packet (Type: 3 (Destination unreachable), Code: 4 (Fragmentation needed)) to the tenant VM.
This ICMP packet may be dropped by HNV on the Hyper-V host cluster node because it is sent with an source IP address that is not eligible to communicate with a tenant VM in the customer address space. The source address is the CA DIP (Customer Address space Dedicated IP), which is automatically configured by SCVMM. The default address range is 10.254.254.0/24.
Configure the HNV GW new using System Center Virtual Machine Manager 2012 R2 Update Rollup 2 (SCVMM 2012R2 UR2). UR2 contains an update that creates the CA DIP Adapter with the SkipAsSource flag set.
As a manual workaround you can configure the SkipAsSource flag on the CA DIP using this command:
Set-NetIPAddress –InterfaceIndex xy -IPAddress 10.254.254.z –SkipAsSource True –IncludeAllCompartments
Network Information for Compartment xy
Ethernet adapter WNVAdap_10486213:
Connection-specific DNS Suffix . :
Link-local IPv6 Address . . . . . : fe80::15d5:d537:4bb9:1fff%xy
IPv4 Address. . . . . . . . . . . : 10.254.254.z
Subnet Mask . . . . . . . . . . . : 255.255.255.248