Hello fellow sunray users, We quite recently got SR3 DTUs and are experiencing screen refresh issues on all of them. For example for the SR3 DTU to show the card login icon completely takes up to 30 seconds. Video streams are nearly impossible to watch at that frame rate. All sunray DTUs are connected to our Cisco 2948G switches and all have 1Gbit/s FDX link . That is with the SR3 and SR3+, not the older SR2 or SR2FS of course.
Now, the interesting/strange thing is the SR3+ DTUs do not experience this issue at all! Further investigation showed a high packet loss (15-20%) at application level (utcapture) with the SR3 DTUs, while there was none with the SR3+ DTUs. There is no packet loss at ethernet level on the switches. Neither for the SR3 DTUs nor for the SR3+ DTUs . I logged a case with Oracle and their final conclusion was that we needed to enable Layer 2 Ethernet Flow control on the switches to be able to use PAUSE frames. With these PAUSE frames the DTU could temporarily "pause" the network stream and hence reduce the (application) packet loss to near 0%. Indeed, this Layer 2 Flow Control does significantly help, but why do we need it all of a sudden? We never needed it before... Here is the explanation I got from the Oracle engineer why we needed this for SR3 but not SR3+: """ SR3's CPU/bus/network performance is not as fast as SR3+. Thus, SR3 ends up losing some of the packets sent by switch if flow control is not turned on. With flow control turned on, we have a better balance between how much the SR3 DTU can process and how fast the network can send data. SR3+ does not have that problem since it can process data faster. """ Does this mean the SR3 units we currently have are faulty? Is this a design flaw? I was wondering if anyone else is also experiencing this problem? BTW this is on SRS 5.2.1 with FW images 4.3_146928-01_2011.06.03.14.41. -- Regards, Kristof.
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