This article summaries tips when configure Load balance for PVS server.

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Instructions

To create Load Balancing for PVS server, 

1. Create TFTP type Service. Choose Protocol: TFTP，Port: 69.
2. Create LB Virtual Server to proxy PVS traffic, Protocol: TFTP, bind newly created Service to Virtual Server 
3. Configure monitor (Optional)
   1. After configuring TFTP load balance default monitor is "Ping-default", and its status will show like below Pic.1

Pic.1



For monitoring TFTP service available status in NetScaler, a specific TFTP monitor is required.

1. Navigate to Configuration>Traffic Management>Load Balancing>Monitors, click Add, input the Name and select type "USER".
2. Script Name choose "nstftp.pl", click Create. Refer Pic.2 
3. Bind the monitor to corresponding service.
4. Successful probe will show like below in Pic.3

Pic.2
 
Pic.3

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This article summaries tips when configure Load balance for PVS server.

1. Citrix Provisioning Services Boot Process refer to: 
https://support.citrix.com/article/CTX227725

2. Does Use Source IP needed in load balance for PVS server? 
No, TFTP service on ADC need not set use source IP.

3. Do we support to Load balancing PVS traffic with Protocol/Port: UDP/69 instead of TFTP:69 in NetScaler?
No, TFTP traffic will only support TFTP:69 load balancing configuration.
UDP/69 load balancing configuration makes NetScaler fail to process TFTP server' random ephemeral port response, which required TFTP traffic protocol level handling in NetScaler.

In NetScaler nstrace, you may find ADC discard TFTP server's Optional Acknowledgement response and send "Destination unreachable(Port unreachable)" to Client directly.
Here is a package captured in test environment:


4. TFTP protocol reference:
    https://datatracker.ietf.org/doc/html/rfc1350/