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Packet loss due to Mac Address Conflict


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#1 Trakeen

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Posted 13 August 2013 - 10:00 PM

I'm currently setting up two DVR systems, and they're some cheapos.  I've set them with static IPs, but I can't do anything about the MAC addresses, and they're identical.

 

I'm getting packet loss and sometimes I can see both dvrs, or just as often only one or the other, and rarely no video at all.

 

I thought about daisey chaining a second router but all it did was act as a bridge.

 

If I change the subnet mask, on the second router from 255.255.255.0 to 255.255.255.128 and connect the second DVR system to it to avoid the MAC address conflict, Could I access it from the PC, and if so, what address would I use, assuming the IP is 192.168.0.151?


Edited by Trakeen, 13 August 2013 - 10:02 PM.


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#2 Trakeen

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Posted 14 August 2013 - 10:37 AM

The only other thing I could think of doing at this point is to measure out how much cat5 I'll need to hardwire the desktop to the router running the second DVR system, but I'd rather not crawl around in the attic, drill holes in the wall, and fish down a line to make this work.

 

Any ideas?



#3 smax013

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Posted 14 August 2013 - 12:49 PM

The only other thing I could think of doing at this point is to measure out how much cat5 I'll need to hardwire the desktop to the router running the second DVR system, but I'd rather not crawl around in the attic, drill holes in the wall, and fish down a line to make this work.
 
Any ideas?


That likely work if you are currently using the ethernet port already on the DVR. You would likely still end up with a MAC address conflict unless you put them on completely different local networks.

Unfortunately, I don't know enough about subnets to know if you can somehow configure one to address the MAC address conflict. I know enough to do typical network setup.

#4 x64

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Posted 14 August 2013 - 02:36 PM

If you break the communication down to it's lowest level, on the same network segment IP addresses become irrelevant - ARP is used to find the MAC addresses of the participating machines and commication takes place between the interfaces with those MAC addresses. So there is no way to fudge it of only switches or hubs separate the DVRs.

 

In order to access both DVRs, you would need a router separating two switching networks. I am not talking about a broadband or cable router - I mean a proper network router, with a routing process separting the two switching networks. I'm not sure if you could get away with using the routing process in a layer 3 switch, but I doubt it - the switch would probably get confused as it works ineternally on MAC addresses.

 

In short you'd probably spend more working around the issue that replacing one of the DVRs



#5 tos226

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Posted 14 August 2013 - 03:31 PM

Same MAC address on different devices sounds very strange, but I suppose it happens due to some sloppy/defective manufacturing, maybe.
It might be possible to change one MAC. In the routers it might be under "Cloning" and isn't really meant for attached equipment, but it might work.

Replacing DVR sounds like the easiest solution really.

#6 Trakeen

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Posted 15 August 2013 - 11:11 AM

Thanks for the information.  I'll see what I can do with a second router before we look at changing DVRs.






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