[VMC] Netscaler VPX load balancing in VMC

Products

• VMware Cloud on AWS

Issue/Introduction

To assist with issues encountered when implementing Netscaler VPX appliance in VMC on AWS SDDCs.

Symptoms:
Customer has installed a Citrix VPX Netscaler instance in VMware Cloud on AWS and are having issues with the DNS response not reaching the Windows Client.

Cause

Promiscuous Mode and Forged Transmits need to be configured when running VPX on vSphere. As promiscuous mode is not supported in VMC, a workaround is required.

Resolution

MAC-Based Forwarding - as Promiscuous mode it not supported in VMC, there are other alternatives for packet forwarding modes. The following documentation can be leveraged when implementing Citrix VPX Netscaler in VMC. Netscaler will not by default use the same MAC address when responding to clients, hence the need for MAC-Based Forwarding. 
- Install a Citrix ADC VPX instance on VMware cloud on AWS
- FAQ: VMAC Addresses for NetScaler VPX Appliance Hosted on VMWare EsXi (citrix.com)
- FAQ: Citrix NetScaler MAC-Based Forwarding (MBF)
- Packet forwarding modes | Citrix ADC 13.1

Additional Information

Impact/Risks:
Customer DNS traffic may be blocked by the Tier-1 Gateway. This prevents a response to the Windows Client.