UDP packet drops
When doing an iperf test outside of pfsense there is a strange packet loss at the start of the test.
UDP packets drop
TCP packets go through.
Was able to confirm it's isolated to an SG1000, on 2.4 SG-2220 no issues were present in this test, but we were able to reproduce on SG1000.
See ticket 15982
#1 Updated by Constantine Kormashev about 1 year ago
I made some tests with simple DNS answer/reply and noticed problem with states overload (250 clients and 250 servers which is 62500 states in total vs 49000 by default) and UDP drops. Just increased states to 500000 and there was not UDP drops until huge UDP load (10000 answer/reply in second)
#3 Updated by Constantine Kormashev 9 months ago
- File sg1k-udp-64b-test.png added
The reason of UDP drop is packet processing slowdown which happens on ARM devices (1k, 3100). I observed ~2-7% for different packet size and one does not change if bandwidth is changed (provided that packet size is not changed). It does not affect data transmission in whole, but UDP tests show drop because UDP traffic generator knows nothing about delay.
Picture below demonstrates this, blue line is number of RX packets one is the same every time ~24.5kpps which is maximum performance for sg1k on 64byte frames.
And no drops for DNS request/answer (~5000pps)
--------------- port : 0 ------------ opackets : 112499 obytes : 8662423 ipackets : 112502 ibytes : 10462483 Tx : 1.31 Mbps port : 1 ------------ opackets : 112499 obytes : 10462407 ipackets : 112506 ibytes : 8662871
#4 Updated by Constantine Kormashev 9 months ago
An important noteThe issue can be found on:
- sg1k for ordinary data transmission
- 3100 for VPN data transmission when CPU is highly loaded
- hardly ever on intel devices, I saw it several times for VPN data transmission with hight CPU load and huge number of packets (usually small/random)
#8 Updated by James Dekker 9 months ago
Tested iperf3 in UDP mode between SG-1000 and SG-2440 (and SG-3100), could not reproduce the bad behavior. Saw a problem on one device, but it appears the issue there was the client's nic (not the SG-1000 itself). Tested with pfSense-netgate-uFW-recover-2.4.2-DEVELOPMENT-armv6-20171104-1805