vpn/ipsec loss of packets with iperf

flurkizflurkiz Posts: 1Registered Users ■□□□□□□□□□
Hi all,

I'm trying to learn vpn using ipsec. I have two routers directly connected and have managed to establish an ipsec vpn connection (can ping both ways, and wireshark show the expected traffic, the router logs tell me the traffic is encrypted).

Everything works fine, except when I try to measure the throughput using iperf. I connect two laptops - one to each router - and run iperf between them. The tcp test seems to work fine but the udp test is strange because the bandwidth drops to zero, and the packet loss is extreme.

This is the UDP test, done using
iperf3 -c 192.168.240.10 -u -b 100M
-----------------------------------------------------------
Accepted connection from 192.168.241.10, port 49291
[  5] local 192.168.240.10 port 5201 connected to 192.168.241.10 port 60305
[ ID] Interval           Transfer     Bandwidth       Jitter    Lost/Total Datagrams
[  5]   0.00-1.00   sec   344 KBytes  2.82 Mbits/sec  55.062 ms  25/68 (37%)  
[  5]   1.00-2.00   sec   192 KBytes  1.57 Mbits/sec  40.821 ms  1189/1213 (98%)  
[  5]   2.00-3.00   sec   224 KBytes  1.84 Mbits/sec  31.882 ms  1507/1535 (98%)  
[  5]   3.00-4.00   sec   208 KBytes  1.70 Mbits/sec  36.552 ms  1463/1489 (98%)  
[  5]   4.00-5.00   sec   208 KBytes  1.70 Mbits/sec  35.369 ms  1508/1534 (98%)  
[  5]   5.00-6.00   sec   192 KBytes  1.57 Mbits/sec  41.073 ms  1488/1512 (98%)  
[  5]   6.00-7.00   sec   192 KBytes  1.57 Mbits/sec  40.673 ms  1500/1524 (98%)  
[  5]   7.00-8.00   sec   200 KBytes  1.64 Mbits/sec  39.240 ms  1523/1548 (98%)  
[  5]   8.00-9.00   sec   216 KBytes  1.77 Mbits/sec  34.439 ms  1482/1509 (98%)  
[  5]   9.00-10.00  sec   200 KBytes  1.64 Mbits/sec  38.041 ms  1536/1561 (98%)  
[  5]  10.00-11.00  sec  80.0 KBytes   655 Kbits/sec  108.943 ms  1499/1509 (99%)  
[  5]  11.00-12.00  sec  0.00 Bytes  0.00 bits/sec  108.943 ms  0/0 (-nan%)  
[  5]  12.00-13.00  sec  0.00 Bytes  0.00 bits/sec  108.943 ms  0/0 (-nan%)  
[  5]  13.00-14.00  sec  0.00 Bytes  0.00 bits/sec  108.943 ms  0/0 (-nan%)  
[  5]  14.00-14.77  sec  0.00 Bytes  0.00 bits/sec  108.943 ms  0/0 (-nan%)  
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bandwidth       Jitter    Lost/Total Datagrams
[  5]   0.00-14.77  sec   118 MBytes  67.1 Mbits/sec  108.943 ms  14720/15002 (98%)  
-----------------------------------------------------------



This is the TCP test, done using
iperf3 -c 192.168.240.10
-----------------------------------------------------------
Accepted connection from 192.168.241.10, port 49292
[  5] local 192.168.240.10 port 5201 connected to 192.168.241.10 port 49293
[ ID] Interval           Transfer     Bandwidth
[  5]   0.00-1.00   sec  2.14 MBytes  18.0 Mbits/sec                  
[  5]   1.00-2.00   sec  3.01 MBytes  25.3 Mbits/sec                  
[  5]   2.00-3.00   sec  2.96 MBytes  24.8 Mbits/sec                  
[  5]   3.00-4.00   sec  2.88 MBytes  24.2 Mbits/sec                  
[  5]   4.00-5.00   sec  2.94 MBytes  24.7 Mbits/sec                  
[  5]   5.00-6.00   sec  2.98 MBytes  25.0 Mbits/sec                  
[  5]   6.00-7.00   sec  2.97 MBytes  25.0 Mbits/sec                  
[  5]   7.00-8.00   sec  2.94 MBytes  24.7 Mbits/sec                  
[  5]   8.00-9.00   sec  2.82 MBytes  23.6 Mbits/sec                  
[  5]   9.00-10.00  sec  2.98 MBytes  25.0 Mbits/sec                  
[  5]  10.00-10.23  sec   758 KBytes  27.0 Mbits/sec                  
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bandwidth
[  5]   0.00-10.23  sec  29.4 MBytes  24.1 Mbits/sec                  sender
[  5]   0.00-10.23  sec  29.4 MBytes  24.1 Mbits/sec                  receiver
-----------------------------------------------------------

Any idea why UDP bandwidth drops? I know that UDP is stateless and that this will cause some packet loss but I'm surprised it is this high, and above all I cannot grasp why the bandwidth gets lower and lower rather than staying at the same level (even if it would be low).

Any help would be highly appreciated!

(Post had been edited to include the code snippets.)

Comments

  • james43026james43026 Posts: 303Member
    I don't think enough info was provided. I can try to help further if you can provide more info. Is IPSEC running in tunnel or transport mode? Can you post the full configs between the routers / ASA's that you are running IPSEC on? If not then at least tell us if you have any ACL's / firewalls that you have setup on either device, and the details on them.
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