gigabit network question

[capz 0]

Hello. I'm setting up an ip based system for our business. The infrastructure is in place for gigabit networking. Right now I have a gigabit router wired to a 10 port gigabit/poe switch. The control station is a core 2 pc with a gigabit lan card. We haven't decided on the cameras. We have a Vivotek FD7132 on loan for testing. My question, first of many, is if the cameras are 10/100, as most are, will that essentially make the network incapable of gigabit speeds? Thanks in advance for any info.

[ver2go 0]

Not necessarily. Let's say you have 16 cameras pushing say 12mbs (assuming HD compressed stream), that is 192mbs of data that needs to go back to the NVR. So the bottle neck it the port/nic to the server. If it was only 100mbs then you would be loosing a lot of packets.

[capz 0]

ok so other 10/100 devices, i.e. print servers, can run through the same switch without affecting the gigabit speeds from the cameras to the nvr pc?

[CCTVConsultant 0]

capz, yes to your last question. anything behind the gigabit switch will be able to take advantage of the available gigabit bandwidth.

[Soundy 1]

One of the main benefits of a switch vs. a hub (which are largely obsolete now anyway) is that every port can operate at a different speed without affecting the speed of the others. All gigabit devices that are connected to the switch will work at gigabit speeds, regardless of what other 10 or 100Mbit devices may be connected.

[capz 0]

Excellent, that's the answer I was hoping to get.

The plan is for 8-10 cameras. Right now we have the one Vivotek FD7132 set up. For 10 of these I don't think we'll need gigabit speeds but I wanted to future proof the network in case we decide to go with megapixel cameras. A local Mobotix vendor offered to let us trial a 3mp camera to compare the two. I'll get some pics up once we do. Thanks for the info.

[thewireguys 3]

Also keep in mind if our using POE switches they are only 10/100 for the camera ports and depending on the switch they have a couple of gigabyte ports for the server and linking to other switches.

[C7 in CA 0]

Thank you for bringing that up. Every time I hear "gigabit poe switch" I wonder how they get poe on a gigabit port...

[capz 0]

"Also keep in mind if our using POE switches they are only 10/100 for the camera ports and depending on the switch they have a couple of gigabyte ports for the server and linking to other switches."

 

The switch has 10 ports, all POE, all gigabit capable. All I really needed was 1 gigabit port for the server but it was hard to find a switch with more than 8 POE ports in the sub $400 range.

[ver2go 0]

Have you considered using power injectors for your POE devices instead? May be cheaper to get a 10/100 with PoE injectors for them than to waste a GiG port for them. Or maybe a 10/100 PoE switch with 2 GigE uplink ports?

 

You can always add another nic to the server as you grow cameras and use 802.ad (link agg) to increase bandwidth.

 

As for the PoE Gig switches, I believe they auto sense or is user configurable. The port can physically do Gig OR be configured for 10/100 with PoE.

[ver2go 0]

Access to the internet is through a point to point wireless bridge from a router in another building. All ip addresses are assigned from the wireless router. (Wireless router->bridge->gigabit switch->wireless router (as access point,dhcp turned off)->cams, printers, clients.

 

I'm a little concerned about this. Where will the cams and nvr in your topology?

 

Will there be cams on one side of the bridge and the nvr on the other side?

 

The bridge will more than likely be your bottle neck in this topology.

[Soundy 1]

Also keep in mind if our using POE switches they are only 10/100 for the camera ports and depending on the switch they have a couple of gigabyte ports for the server and linking to other switches.

 

This is what I've been using most often - 8-port 10/100/PoE for the cameras, with two gigabit uplink ports, one for the DVR and one for the NAS... been pretty happy with this unit so far: http://a-power.com/product-6481

 

Thank you for bringing that up. Every time I hear "gigabit poe switch" I wonder how they get poe on a gigabit port...

 

http://a-power.com/product-5428

"SRW2024P Managed Ethernet Switch PoE with WebView"

"24 x RJ-45 10/100/1000Base-T LAN"

 

http://a-power.com/product-6485

"SGE2000P 24-Port Gigabit Managed Ethernet Switch with PoE"

 

Exactly how they do it, I don't know... consider that phantom-powered microphones run the power over the same wires as the signal, and have for decades - it's not a totally foreign concept It could also be as ver2go suggests, the switch auto-senses and runs either GB, or reverts to 10/100+PoE as needed.

 

I would expect, if you look up the PoE spec, methods of handing either scenario would be documented there.

[capz 0]

"I'm a little concerned about this. Where will the cams and nvr in your topology?"

 

The cams and nvr pc are wired to the gigabit switch in the remote location. The router across the bridge just assigns ip addresses and provides internet access for wan viewing.

 

The switch we're using is a 3Com 3CDSG10PWR, bought for $375. I can't post a link as I'm a newbie here. I haven't tested network speeds yet but the green lights to the router and nvr confirm 10/100/1000 on those ports. The amber light on the camera port confirm 10/100.

[Soundy 1]

I think you'll find most cameras are only 10/100, as there's not (at least with current technology) a lot of benefit, if any, to using gigabit on a camera, other than "just because we can". A single camera simply doesn't need the bandwidth, so there's no justification for the added expense.

 

And if, as ver2go posits, gigabit and PoE are mutually exclusive functions, I suspect you'll find PoE winning out almost every time when it comes to these sorts of devices.

[Sawbones 0]

The other posters are exactly correct.... PoE precludes GigE being used on the same run of Cat6, since one of the twisted pairs is taken up for power transmission and cannot be used for data (at least in the implementations that I've seen).

 

Somebody may come up with a solution for that (perhaps something similar to powerline networking), but I don't know of any common conventional switches that do it.

[Soundy 1]

PoE actually uses TWO pairs - 10/100 uses only the orange and green pairs (assuming standard 568a or 568b wiring), leaving the blue and brown pairs free.

 

And actually, PoE spec DOES allow for power to be run over signal pairs, even with 10/100... see the diagrams near the bottom of the page here: http://www.joejava.com/poe.htm - the picture on the right is actually exactly the same way "phantom power" works for microphones and other phantom-powered audio gear.

 

Given that, there's no reason it won't work over gigabit either.

[Sawbones 0]

Interesting... I learned something today... thanks!