Does the CSM load balance to CNR servers (DHCP)?
A. The CSM does not handle DHCP packets differently from generic UDP packets, which means that it will create a flow entry identified by a 5-tuple (src/dst IP, src/dst L4 port, protocol: udp) and can NAT source/destination IPs if needed (for example for server originated “connections”, that might need to have their source IP NAT’ed to the VIP) Since UDP does not have packets indicating a termination of the “connection”, the CSM will remove a UDP flow entry from its tables when the “idle timeout” for that flow expires. The “idle timeout” can be set, on a per-VIP basis, to as low as 4 seconds. As for specific DHCP LB, there are various issues that complicate the selection of the correct server, including the fact that any request coming from a client that does not have an IP address yet will be sent with source-IP equal to all 0’s.
