In my practice, powering the device and getting a picture from it at a considerable distance from the switch turned out to be not the easiest task. Especially when networks depart from one piece of iron to several cameras at different distances.
Any more or less complex device periodically hangs. Something less often, and something more often, and this is a dogma. Most often this is solved ... right ... with this:
And if there are no necessary hands on the other side of the tube, you will have to tear your ass off the chair and go / ride / fly to the device.
It is especially unpleasant if this device is somewhere under a roof or on a pole ... or in a remote office.
Savings is the main scourge of remote administration. Sometimes a nayalnik-ma finds a camera / switch / router on aliexpress and explain why this piece of iron costs 700 rubles, and since you offer more than 5k, it can be an impossible task. Especially if this device is already in stock and they turn to you according to the principle “why doesn’t it work for us?”. The customer is always right, especially when he calls, as little as possible. And this means that this most Chinese f***ing bad device should have some independence and it is desirable to “kick” automatically even before the client notices it.
Managed PoE switches are ready to save the situation, since they are presented in huge numbers on the market.
And here is the problem number One: by whom, or rather, than to monitor, so that in the event of a “sticky” device, push the power reset command on the PoE switch port. Raising and configuring the server is additional gestures and hardware.
Let's say I have 15 video cameras, a video recorder and… that's all. At the same time, 7 are located at a distance of less than 100 m, another 5 up to 150, and another 3 at a distance of 200 m. It is necessary to simplify the infrastructure so that people come to this facility only with preventive measures.
The solution is quite simple - the presence of a PoE switch that can monitor cameras and reset power on the port, and also “reaches” over the cable for a distance of 200+ meters
Mikrotik
With two certificates (MTCNA and MTCRE), my first look fell on Mikrotik. The choice of this manufacturer of models with index P is small, for example,
IMHO, too small set of settings. What happens if the camera thinks and misses a couple of pings? — in reboot!
What if the camera just died? Mikrotik will cut it off every minute? ..
In my practice, there was a large amount of marriage in the CCR on the power supply. And what's the point in a PoE switch if it has a high risk of dying on power in six months? ..
In addition, I did not find information that Mikrotik can work with wires at least 150+ meters long ...
Zyxel
When studying representatives of competing vendors, I came across . Switch from Zyxel GS1350 series. It costs significantly more than Mikrotik, but at the same time, I did not notice any problems with Zyxel with “weak” power supplies.
Zuksel positions the GS1350 switches as designed specifically for video surveillance systems. The switches detect that the camera is “stuck” and reset it by power.
Freeze detection method
Before I started getting acquainted with this device, I imagined that the switch analyzes the type of traffic and as soon as the video stream ends, the switch resets the power ...
But everything turned out to be much easier.
"Auto PD Recovery" can work in two modes:
- LLDP, that is, the device itself provides information about itself, if, of course, the device supports. LLDP answer came - it means the piece of iron is "alive". If there is no answer, we forcibly “cut” the power supply and wait for a response.
- Ping. Where is easier? We ping - No answer - Reboot!
The number of unanswered pings, the reset time and the number of power resets are configurable. Which is quite logical, because there is no point in "kicking" a piece of iron if it did not start the third time.
But I didn’t understand: what is the specialization in video cameras HERE?
In this way, you can monitor any network device. Even the one that does not support PoE.
We order such a gadget from aliexpress and any network device turns into PoE.
If the gadget freezes, the switch will reset the power on the port and in the logs we will see something like this:
233 Sep 07 17:24:41 DE interface: Port 4 - ReoLink link up 100M/F
234 Sep 07 17:24:39 DE interface: Port 4 - ReoLink link down
235 Sep 07 17:24:32 DE interface: Port 4 - ReoLink link up 100M/F
236 Sep 07 17:24:30 DE interface: Port 4 - ReoLink link down
237 Sep 07 17:24:26 NO system: PethPse Port 4 - ReoLink OnOff Trap, Port Detection Status is Delivering Power
238 Sep 07 17:24:24 DE interface: Port 4 - ReoLink link up 100M/F
239 Sep 07 17:24:04 NO system: PethPse Port 4 - ReoLink OnOff Trap, Port Detection Status is Disabled
240 Sep 07 17:24:02 DE interface: Port 4 - ReoLink link down
241 Sep 07 17:24:01 WA interface: Port 4 - ReoLink PD failure is detected and reboot due to Auto PD Recovery (ping mode)Maximum cable length.
On page it is said:
The use of the Extended range mode in these switches allows you to increase the maximum distance to powered devices up to 250 meters.
We are accustomed to any advertising prospectus to be skeptical.
I crimped the two ends of the new bay (305 meters) and stuck one into the chamber and the other into the switch. The camera did not take off ... It seems to be expected ^_^
I sat, scratched a pumpkin - went into the settings, checked the box "extended range", and ... ten seconds of silence - drum roll ... the camera started working! At 305 METERS!
No packet loss!
Thus, the GS1350 series switch did not reach the declared 250 meters, but as much as 305 meters!
True, perhaps the cheat also lies in the quality of the cable:
If a longer length is required, several cable lengths can be joined through some kind of repeater. You can also connect another poe switch at the end to connect several devices.
For example, via UPVEL UP-215SGE (I didn’t check how reliable it was. I just fell into my hands.) It is powered by PoE and powers devices via PoE.
But this is a separate topic for specific conditions, as it requires design taking into account all factors.
When the “Extended range” option is enabled, the port will automatically set the 802.3at protocol and set the power budget to 33W.
But it is worth setting priorities in case when all consumers begin to actively eat ... Ports with a low priority, in case of a shortage of power on the switch, will receive the requested power last.
lightning protection
The second question when placing devices in the fresh air is protection against voltage surges.
ESD/Surge Protection value:
ESD - 15 kV / 8 kV (Air/Contact);
Surge - 4 kV (Ethernet Port).Note. ESD - ESD protection, Surge -
surge protection. If there is a static discharge in the air up to 15
kilovolt, or 8 kV electrostatics at close contact, or temporary surge
voltage up to 4 kilovolts - the switch has a good chance to survive such
trouble.
Well, on the case there is where to attach the ground.
I hope I don't have to check this ^_^
Continuous PoE
Provides power even if the device is not responding. This option is enabled by default. Don't forget to check this option before updating firmware on cameras. Otherwise it might be annoying...
Cisco like CLI
For console lovers, as well as to automate settings, you can use the familiar Cisco-style CLI.
If you do not use, for example, telnet / snmp and other protocols, then I recommend turning them off to increase the security of the device.
Not without a fly in the ointment ...
The switch has a menu item "Cloud Management"
But when I try to register I get this
Currently, these devices are supported on not yet enabled. The manufacturer promises to add them in 2020. In this case, you will not need to update the firmware of the switch!
Conclusion
Zyxel GS1350 is the only switch that has satisfied my needs so far:
- managed with a standard set of functionality
- cable length 200+ meters without joints
- monitoring and rebooting PoE consumers
- ease and flexibility of configuration.
Perhaps there are other solutions on the market that will cover my needs, but I have not found them yet.
I invite those who wish to discuss the article to Telegram to the chats I created:
1. — Thematic chat by Zyxel
2. — Thematic chat on Mikrotik
Source: habr.com