A series of tests were run to determine the effects of a VPN connection on wireless network performance. In particular, we were interested in the performance "hit" one might take when accessing a VPN via a wireless connection (we tested a wired connection for comparison). All tests were performed using Iperf-1.1.1. The original test was done using a PPTP VPN connection. The second, more recent test was done using the Cisco IPSec client for Windows 2000 (beta "release 2.6 beta 2").
Cisco IPSec Client Test [data for wireless unencrypted and wireless encrypted only]
Here is a summary of the results (see below for more details and the conclusion):
|
Test#
|
Protocol
|
MBytes transferred |
Bandwidth (Mbps)
|
|
TCP
|
6.4
|
4.9
|
|
|
(non-encrypted wireless)
|
UDP
|
1.3
|
1.1
|
|
TCP
|
4.8
|
3.6
|
|
|
(encrypted wireless)
|
UDP
|
1.2
|
1.0
|
Testing setup for test #1 and test #2:
Without Cisco IPSec client connection to VPN (i.e., just the regular wireless connection):
TCP
With Cisco IPSec connection to VPN (i.e., the same wireless connection as above but going through an IPSec tunnel using the Cisco IPSec W2K beta client software; and the same Iperf settings as above for both TCP and UDP):
TCP
Here is a summary of the results (see below for more details and the conclusion):
|
Test#
|
Protocol
|
MBytes transferred |
Bandwidth (Mbps)
|
|
TCP
|
11.3
|
8.8
|
|
|
(non-encrypted wired)
|
UDP
|
10.2
|
8.2
|
|
TCP
|
10.8
|
8.4
|
|
|
(encrypted wired)
|
UDP
|
9.4
|
7.5
|
|
TCP
|
5.3
|
4.1
|
|
|
(non-encrypted wireless)
|
UDP
|
6.1
|
4.8
|
|
TCP
|
5.0
|
3.8
|
|
|
(encrypted wireless)
|
UDP
|
4.7
|
3.8
|
Wired throughput test without PPTP connection to VPN (i.e., just the regular wired connection):
TCP
Wired throughput test with PPTP connection to VPN (i.e., the same wired connection as above but going through a PPTP tunnel using MPPE 128-bit encryption and no compression; and the same Iperf settings as above for both TCP and UDP):
TCP
Testing setup for test #3 and test #4:
Without PPTP connection to VPN (i.e., just the regular wireless connection):
TCP
With PPTP connection to VPN (i.e., the same wireless connection as above but going through a PPTP tunnel using MPPE 128-bit encryption and no compression; and the same Iperf settings as above for both TCP and UDP):
TCP
The "wired tests" (tests #1 and #2) would seem to indicate that you take about a 4.5% hit via TCP and an 8.5% hit via UDP for going through the VPN. The "wireless tests" (tests #3 and #4) seem to indicate that you take about a 7% hit via TCP and a 20% hit via UDP for going through the VPN. These tests were done for comparison only. We wanted to determine if any differences in network throughput existed between wired and wireless VPN and non-VPN connections. The above numbers show our results. It should be noted that PPTP was used as an example VPN protocol only--it is NOT the VPN access method UCAR will be implementing. Please visit the UCAR VPN testing page for more information.
Cisco IPSec Client Test Conclusions
These wireless tests (tests #1 and #2) with the Cisco IPSec client over a wireless connection seem to indicate that you take about a 25% performance hit via TCP and an 8% hit via UDP for using this type of VPN connection. Please visit the UCAR VPN testing page for more information.