An emerging problem is retransmission with inline VPNs. When the host-generated packets are too large for the encrypted channel, the host has to retransmit the original data using smaller packets.
Increasing bandwidth and frame-rate demands exacerbate both of these access problems. The only fix is to change the characteristics of the network--by throwing more bandwidth at the problem, for instance--or the application, by using a lighter-weight encoding algorithm with lower frame-rate utilization or one that uses less bandwidth. Either way, the trade-off is a decrease in the quality of your voice and video traffic.
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Network-access equipment on the server segment. Although user-side devices are likely to drop some traffic at the WAN boundary, network-access equipment on the server side can drop a lot more if the network isn't tightly managed.
For example, a VPN or SSL concentrator on the server side of the network usually exhibits performance problems long before the end user's equipment starts to hiccup, while a router handling transmission flows for a few thousand remote users has major queue-management demands and can get clogged with traffic (unless you increase your available WAN bandwidth).
Server. That's where most IT pros look first when performance degrades. Many server functions--excessive task switching, database performance, disk contention and disk swapping--can cause problems.
How To Implement Performance Management
