I am having performance problems with SG300-20 switches. I chose them to put in a few offices needing access to several different VLANs and since they are fanless this seemed the perfect choice (we have other Cisco devices, too). After putting one in service for tests, I see quite some performance problems. Let me describe the environment:
We have Oracle SunRay ultra thin clients. The clients (SunRays) connect to Catalyst 2960s switches.
1. When I connect a SunRay directly to an 2960s (100F), the SunRay server shows very little packet loss (around 0.02%).
2. When I have an SG300-20 between the SunRay (100F) and the 2960s (100F), then the packet loss is comparable to 1. that is around 0.02%.
3. When I again, like in 2., have the SG300-20 between the Catalyst and the SunRay, but the uplink (Catalyst to SG300) ist 1000F, then the packet loss rises to somewhere between 7 and 13%!!!
4. When I replace in 3. the SG300-20 and put a 3Com (OfficeConnect Managed Switch 9) between the Catalyst and the SunRay, the packet loss reported by the SunRay server is 0.000%.
In these tests I only had 2 ports used on the SG300 and the 3Com, the uplink and the client and only access ports where used, no tagging. The firmware installed is:
SW version 18.104.22.168 ( date 02-May-2013 time 14:55:01 )
Boot version 22.214.171.124 ( date 11-May-2011 time 18:31:00 )
HW version V02
Since the SG300-20 does wirespeed forwarding, I would expect no packet loss at all, at least no a very important one. Is there something in the configuration to be tweaked or is this a known firmware problem?
I should also mention that I did not see anything special on the port of the Catalyst, nor on the SG300-20. I also tested with another SG300-20 and had the same behavior.
Tried the downgrade to 126.96.36.199 + factory reset + minimal config (VLANs) for testing, but I see no difference in quality.
I may add that the SunRay traffic is quite bursty and UDP and this may be the source of the problem. Doing some tests to render to whole a bit more reproductible, I use iperf with 2 PCs:
A 192.168.254.21, connected 1000F in our network (iperf server: iperf -u -s)
B 192.168.254.11, connected 100F in my office (iperf client), connected to the various test switches
The interesting part is when A sends B the data too fast (150M), with both Cisco switches, the received data is just a small fraction from what it is with the 3com switch and I think this is related to my poor performance with the sunrays because the sunray servers are all connected 1000F.
B on sg300-20> iperf -u -c 192.168.254.21 -r -b 150M
Well no, the SunRays are very dumb devices and they do only auto negociation. Moreover, the SunRay 2 I am using only has an 100base-T interface (I also made some other, earlier, tests with an SunRay 3 which has an 1000base-T interface, but I suspect that the SunRay CPU could not cope with the network traffic (lots of pause frames received on the switch (c2960s)), because the video quality was much worse compared to an 100F negociation).
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