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CCTV System Unstable



Currently I am working on a system where we have Cisco and Ericsson as backbone for the Network. for Cisco we are using 4507 as core (HSRP is running over there) and Transmission nodes are between the Core and Access Switches.


The CCTV Cameras are connected to the Access Switches and suddenly the video starts to blink on the Monitoring Station for These. Still unable to figure out the reason behind this.


Any suggestion on how to proceed with troubleshooting for this?






When you say "blink" do you mean the screen goes black and then back on?

How often?

Does it do the same thing on all the cameras or a group of cameras?

if you ping the cameras with a continuous ping do you lose and pings?

Does the "Blinking" show on the recorded video or just watching it live?





Dear Burleyman,


By "Blink" I mean the video goes off and comes back.


It happens occasionally. Not Continuous and It happens only for those Cameras where we have Transmission Nodes in between. for Stations that are directly connected to the LAN, its working fine.


When We PING the camera's, PING is continuous no Drop what so ever.


While Watching Live we have observed this not sure about the Recorded one.





I also see you have posted about issues with this before, correct?

Does this diagram still show how things are connected?



Yes! this Diagram is correct and we are having issues only for stations that have SDH node in between.

When you say, this is what you are talking about correct? SDH (Synchronous Digital Hierarchy).

So based on that....

If you are connected to the 3750 switch on the other side of the SDH network does the video "blink" there or is it good?

Do you have QoS configured on the switchports, uplinks, and the network through the SDH network?

If you do not you will need to design QoS through that network so it will prioritize the Video traffic correctly or this will probably not go away.

The other option would be to put another CCTV server at the other location and point the camera to that server.

The issue more than likely lies in the SDH network at least that has been my experience with these types of issues.



Yes by SDH I mean Synchronous Digital Hierarchy....


Yes the Video Blinks only for cameras that is connected on the other side of the SDH network.


By implementing QOS on the SDH network means configuring QOS inside SDH or LAN Network? On LAN Network right now there is no QoS.





My gut tells me the latency is in the SDH network so yes you would need to configure QoS through that network. I have found QoS is almost always setup for Voice but almost always forgotten for Video. I have seen this in many networks because the network people don't fully understand video through the network.



So you mean we need to configure QoS on SDH side not on the Cisco Switches?

As a best design it should be the whole network where cameras are connected just like you would with phones.

Check this document.



Martin Carr

The nature of CCTV is sensitive, as it's real time (much like VoIP). As such not only is adequate bandwidth important, but also latency.

Is it just that workstation that is affected?


Dear Martin,


To view the Stations over CCTV, we have Monitoring Workstations and On those workstations we are observing this thing that Camera's blink. Video will disappear and comes back within seconds.


For CCTV we have Storage Node for storing the Streams and during the blinking time, that RMS software shows packet drop/frame drop as well. But the PING remains Continuous. 





Have you performed troubleshooting on the access switch, i.e. logs, CPU usage etc?


We have 2 scenarios, one is where all access switches are connected directly to the core and on those stations we are not facing any issue.


other scenario is where we have SDH Nodes in between Core and Access Switches and we are facing this camera blinking and frame loss issue only for those stations.





Also do you see the blank spot on the recorded video? Need to see if the recorded video is ok or if it has the blank spot as well. I have seen many many times where the recorded video is good and there is ghosting and pixelation  on the viewing station.