A VPN operates at layer-3 using the IPSec protocol. It supports TCP, UDP and other layer-3 protocols. Some IPSec VPNs also use UDP and TCP to encapsulate IPSec packets in order to pass through NAT firewalls, routers and proxies.
Related Q&A from Retired Expert - Mark Tuomenoksa
Have a question for an expert?
Please add a title for your question
Get answers from a TechTarget expert on whatever's puzzling you.