Network Cabling Mystery

I was at a small client yesterday and ran into a puzzling situation. He has an eight camera IP survielence system at his store.  This is a small store with only one Pc in addition to the camera system. Up to a week ago, they couldn't get any Comcast internet service so they used an ATT Air card installed on their Sonicwall firewall/router for web access. That worked fine.

Since Comcast came in, they installed their router in front of the Sonicwall and the PC has continued to work properly with web access going through Comcast.

The original camera system installer couldn't get the system viewable remotely (probably due to the limited bandwidth) so he just left it viewable locally at the NVR. I was called in to get them viewable remotely over the Comcast connection.  I noticed none of the camera's network ports showed a link light or blinking LED's showing data activity.  I checked the NVR and updated it's network settings to work with Comcast. There is a built-in POE switch on the back of the NVR. I viewed the cameras on a monitor connected to the NVR so I know they are connected and recording.  The network port for the Comcast connection on the NVR doesn't have any LED's lite either. I checked the Comcast router and the NVR cable does not have a Link Light and does not show activity but I can view them remotely on my smartphone.

With my Windows 7 laptop plugged into the Comcast router, I can ping and log into the DVR without a problem.

I called the NVR vendor and he had never heard of a situation like this.  The cabling is all Cat5 and appears to be terminated properly. I put a cable tester on the cable from the NVR to the Comcast router and it passed a cable test.  Any idea why there are no link or activity lights?
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Tony GiangrecoAsked:
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Dr. KlahnPrincipal Software EngineerCommented:
Have you drilled the necessary hole through the Comcast router's built-in firewall so that the NVR's port number (whatever) is visible to the Internet?
Tony GiangrecoAuthor Commented:
Yes, but that is not the issue: link lights
Salah Eddine ELMRABETTechnical Lead Manager (Owner)Commented:

Can you access the Comcast router and check if the port in enabled or not? have you try to connect your computer to the comcast router anc check if the light are up and you can access Internet?


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Tony GiangrecoAuthor Commented:
Port enabling has no effect on link lights. yes, the ports have been enabled and remote access has been attained to the DVR from outside.

Why are there link lights on the DVR network connections or the DVR cable plugged into he Comcast router?
Salah Eddine ELMRABETTechnical Lead Manager (Owner)Commented:

If you remote access has been attained to the DVR from outside, what is the problem you are looking to solve?

If the port is working and only link/act led are not blinking, maybe the leds are damaged!!!


Tony GiangrecoAuthor Commented:
Yes, I agree the system is working, but for future troubleshooting, I'd like to get the Link light and Network Activity LED's working so I can tell if the connection is working properly like on every other router & switch I've ever worked on.
Salah Eddine ELMRABETTechnical Lead Manager (Owner)Commented:

Maybe there is link/activity led in the other side of the router!! witch can be usefull.

What's the Comcast router reference?


Tony GiangrecoAuthor Commented:
The link light for the DVR cable that plugs into the router is off. The Pc that plugs into the router has a link light.

This makes me believe the cabling used for the DVR does not meet the Cat5E specs in some manner. I've reported it to the DVR installer but have not received a response.

Any comments on this opinion?
I've requested that this question be deleted for the following reason:

The question has either no comments or not enough useful information to be called an "answer".
Tony GiangrecoAuthor Commented:
Sorry, I never received a suggestion that answered my question. If you want to open this up to additional experts and allow them to review the situation, I'd appreciate it.
What is the brand/model of the NVR?

Did you try moving the port on the router you plugged the NVR into? Maybe that particular port's lights doesn't work?

How about putting a switch between the router and NVR and seeing if the switch's link and activity lights come on?
Problem #1 - you're trying to use Comcast's hardware as a router, and ignoring a much more capable (and previously functioning) Sonicwall.

Comcast is an ISP.  Their hardware is made for their convenience, not necessarily for business or smarter-than-a-fourth-grader home use.

Put the Sonicwall back in place.  Make the Comcast internet handoff to X2 or X1.  You can keep the cellular as a backup, or as a secondary in load-balance or failover.

There was no real reason to wire up Comcast's router that way in the first place.

Ask for an Ethernet handoff.  If they can't do it, then turn their router into a bridge...not doing routing.

If they are like Verizon, consider replacing their hardware altogether, because there is probably a back door allowing them access that you cannot disable.
David Johnson, CD, MVPRetiredCommented:
when you say the link light.. are you referring to the light on the router or on the dvr or both?
I put a cable tester on the cable from the NVR to the Comcast router and it passed a cable test.   did you also test the other cables? What quality is your tester? is it more than just a continuity tester?

with POE which seems to be working have you measured the voltages at the camera? not using 10 cameras when the DVR only supports poe for 2 ?

have you tried a known good cable.. (like the one on your laptop) or if you plug your laptop into the cable going to the dvr from the router .. the router lights come up.. some routers have a cable test function in their menus.
Salah Eddine ELMRABETTechnical Lead Manager (Owner)Commented:
As everything is working and only light not showong status  and since the model or refrrence not provided we cannot provide additional answers!

please provide router and nvr models and references


Is the link light showing up/down status or speed?  If the display is set for speed, then the PC and DVR may be connecting at different speeds. PC at 1Gbos and DVR at 100Mbps, with indicator showing speed...this would be working as expected.
Thierry Hulseboschsystem administratorCommented:
Have you tried changing the cable for  a crossed pair? (or vice versa)
Tony GiangrecoAuthor Commented:
The DVR is an ICrealtime NVR-708MP

The unit is fully functional except the Link Lights (LED's) on each network connection at the back of the NVR never light up at all.  The unit has been turned off and on, and the lights never light up at all - even during the boot up process (Camera POE connections and network connection).

The NVR is setup for online use and I've installed the app on the owner's smartphone allowing him to see the cameras from outside the location so i know the connections are setup, ports are forwarded and working properly.

This should answer most of the questions.  Let me know if you have any suggestions other than deciding the NVR is defective (Which may be true).

On the Comcast router, where the NVR's network connection plugs into the Comcast router, that cable's connection does not light up on the back of the router either, just on the front of the router showing an Ethernet connection is live on that port.  I've moved the NVR's cable on the Comcast router to another network connection on that router and the NVR's connection LED's never light up. The PC plugged into that router does light up as normal.

All cabling is cat5E. All cable connections look good. i've put a cable tester on the DVR cable and it tests perfect on all connectors.

I've spoken with the vendor and they have no explanation.

Here is a doc on the unit:
Tony GiangrecoAuthor Commented:
The cabling runs through the walls. i have not changed the cable because I'd have to run a cable through the store and it would be a safety hazard with customers and employees.
Thierry Hulseboschsystem administratorCommented:
TG-TIS, you could use a cable extender, to connect a crossed cable.
Not ideal, but it will rule out the possibility of use of a wrong cable, without replacing the entire cable at once.
Salah Eddine ELMRABETTechnical Lead Manager (Owner)Commented:

As I told you before, as everything is working why asking for the light to be on??

You didn't provide the Comcast router brand and reference!!

For the DVR (not an NVR which consider networking properly) it's a Chinese DVR with only the brand name customized, if you had a look on the document and the way the network configuration window displayed the output you will see that no consideration regarding text format every thing is in CAPITAL letters.

If you you use a good known brand DVR you will have you led light up!! else using such kind of Chinese DVR you will be happy to that works and no need to focus on why the led is not UP.

Best Regards.


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Tony GiangrecoAuthor Commented:
Ok, I'll consider it to be a problem with the NVR. Thanks for all your suggestions.
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