The 100 meter per segment limitation on Ethernet
The 10BASE-T, 100BASE-TX and 1000BASE-T standards have a length limitation of 100 meters per segment, that is, from the origin to the destination with the same cable, the maximum allowed distance indicated by the standard is 100 meters, from this length, it is very likely that we will have sporadic disconnections, synchronization at lower speeds (10Mbps or 100Mbps) and other problems such as frame corruption. In most cases, we solve this by putting switches in between, at a more or less homogeneous distance and always below the 100 meters indicated by the standard, to make sure that we are not going to have any problems. For example, if we want to cover 160 meters from an origin to a destination, the most normal thing is to place the switches about 80 meters each, although this will depend on the physical space where we want to install the network.
The manufacturers have improved and evolved the switches, so that with these 10BASE-T and 100BASE-TX standards, we can go beyond the 100 meters indicated by the standard. Currently, we have switches that can reach up to 150 meters, 200 meters and even 250 meters like this D-Link DSS-100E-18P model, of which we already have a complete analysis in RedesZone. Thanks to this possibility that these Long-Range PoE switches offer us, we will be able to cover much more distance than we normally would with PoE switches, which reach up to 100 meters at most, complying with the standards.
How does the Long-Range PoE of the D-Link DSS-100E-18P work?
In the case of the D-Link DSS-100E-18P, we have a physical button that allows us to activate the «Long Range PoE» mode on ports 8-16, these ports will be capable of providing PoE + power (up to 30W) through of the network cable, although it will do so at a maximum speed of 10Mbps, because with such a distance it is not possible to use the 100BASE-TX standard to synchronize at speeds of 100Mbps.
This model is aimed at long-distance video surveillance, we must bear in mind that IP video surveillance cameras will always have a bitrate lower than 10Mbps, even if they are Full HD 1080p, in addition, the new cameras support the H.265 standard that we allows higher video compression and the same quality as with the H.264 video codec. If you are going to use Long-Range PoE, our recommendation is that you make sure that the IP camera supports the H.265 video codec to have the lowest bitrate and the best possible image quality.
Could it go beyond 250 meters?
Yes, but you will need to make use of PoE extenders, such as the D-Link DPE-302GE model that will allow us to extend the length by an additional 100 meters. Let’s imagine that we need to cover 300 meters of distance, we can make use of the DSS-100E-18P switch plus a DPE-302GE adapter, in this way, we can cover this distance without problems. However, if you need to go further, you will always be able to buy a maximum of 4 PoE DPE-302GE extenders plus the DSS-100E-18P switch, therefore, we can cover a stretch of up to 650 meters maximum.
With the Long-Range PoE switch and this special PoE extender, we can increase by 100 meters per segment, logically, the speed we will obtain will be up to 10Mbps maximum. A very important recommendation if you are going to have to cover long distances is to take great care of the wiring and connectors that you use in the installation. Our recommendation is to use Cat 7 S / FTP cabling, which has multiple protections against external interference, in addition, it is more rigid than typical Cat 6 UTP cabling, therefore, the signal will arrive better and without attenuating so much, remember that if you are going to cover long distances you should not bend the wiring too much, it should go as straight as possible. The RJ-45 connectors to use are also very important, in this case, it is highly recommended that they be shielded, to protect the signal as much as possible and not have signal losses through the connector.
As you have seen, nowadays covering distances with Ethernet network cabling greater than 100 meters is quite simple, however, you must take into account the network equipment to be used, switches, PoE extenders and also that the cabling is in perfect condition. state, otherwise, you will have problems of loss of synchronization, packet loss due to problems with the frames etc.