Latency Issues

Hi. Pitching in on this one, as I'm presently at the venue in question ...

Couple of minor amendments to John's description of the system. The switch at the control end isn't being used at the moment. One ethernet o/p on Eos connects to a 4-port gateway driving the venue dimmers, another one directly feeds the snake running to the onstage racks. Snake length is 75m (it says on the end, and I believe it!).

Investigation revealed the existence of an unnecessary 20m extension between Eos and control snake - that's now removed, so let's see if it makes a difference.

Switch in onstage rack is a Cisco SR216.

Difficult to achieve any fault-finding "while the lag is apparent" ... it only ever manifests itself during a performance, and then only for a handful of cues before going away again. I can't be pinging gateways or photographing switches while op'ing the show, and there generally isn't anyone else around to do so. The first opportunity we have to do this will be next week when John rejoins us and there are two of us around who can look into this simultaneously.

Haven't had a window of opportunity to open the console and look at DIP switch settings, nor to ring out the network cables in the snake with a tester.

Photo of the output from ETC_IPERF_CLIENT.exe is attached.

I'll see what happens during the performance tonight - after that, I'm not back with it until next week, when John also returns.

Gareth.

Hello Gareth,

These figures would suggest that your network is running at 10Mbit and at half duplex. This is far from ideal.
Unfortunately the Cisco SR216 doesn't have a speed duplex indicator, so we can not instantly establish where the speed drop is located.
I would maybe try the iperf test again, but with the laptop directly connect to the EOS - this would establish the maximum speed obtainable.

A 95m (75m + 20m) is very close to absolute limit of 100m port-to-port for Ethernet and it is generally accepted that 90m should be the maximum working limit. At long distances Ethernet is unpredictable. I would wager that this would be the cause.

Regards,

Marcus

Hi Marcus,

Update from tonights show report.

Lag is still apparent, about 5-6 cues went with Lag issues, note the lag is with the output to the rig, the desk is changing as it should, sometimes its steppy, sometimes it go and delays/ snaps up.

Im slightly concerned as this is the second snake which is now defiantly under 90m's in length.

Ill give a call tomorrow to the office and have a chat/update.

John

Hello John,

Ethernet length is a very important aspect and is often over looked. It worth noting that due to way ethernet cable is constructed, that the outside jack length is not a true indication of the length of the twisted cores within.

I'd also note that the Cisco SD216 is a rebadged clone of a cheap netgear switch.

I would say that you have a couple of issue on this setup.

So now we need to establish where the speed drop is occurring, as I would expect the iPerf results to be in the region of 80-90Mbits/sec and at the very least 10MBits/sec.
With that in mind, could you iPerf test between the eos and the laptop in the following setups:
1)Laptop plugged directly into the EOS switch
2)Laptop plugged directly into the EOS motherboard (you will need to open the console up for this)
3)Laptop plugged directly into the far end of the long snake while connected to the EOS switch (i.e. Not with the on-stage switch)
4)Moving the on-stage switch to the control room and via short cables, laptop via the switch.

Regards,

Marcus