Using UbiSwitch to aggregate GigE Vision Camera streams

– Copied from a customer query –

I’m hoping you can help. We have a question about GigE Vision on the UbiSwitch for a product we are designing. The product involved using 3 x 24MP GigE Vision cameras, which we need to condense to a single fibre connection back to a control box.

The cameras have a theoretical bandwidth of 122MB/s. Images from the three cameras are intended to be synchronised, so packets from all three will arrive at the switch simultaneously. There will be an additional microcontroller with very low bandwidth requirements – it sends back occasional sensor data.

Does this seem feasible to you, making use of the Ubiswitch?

UbiSwitch uses an ethernet switch fabric that is non-blocking, meaning you can receive and send 1Gbps on all ports simultaneously. In addition to that, the SFP ports on UbiSwitch are 10Gbps capable.

This means that you should be able to receive and stream 3 streams of 1Gbps (125MBps) into a single 10Gbps via one of UbiSwitch’s SFP ports, without issue.

Do bear in mind that the UbiSwitch does not yet support any timing protocol (like PTP), and thus if the packets arrive simultaneously, they are likely to be buffered (queued) before sending out onto the SFP port). This is to say, a switch introduces a non deterministic latency (usually quite small), and there is no way to account for that (until PTP is activated on UbiSwitch).

High level, what you want to achieve should work. If you need specific timing over ethernet then you would need to use a protocol like PTP; something that is possible on UbiSwitch but not yet activated. We are working on switch management software for that for release in 2024.

On our architecture we’ve got three GigE Vision cameras and then a standard Ethernet device [with very low bandwidth requirements]. Is this sort of mixed GigE Vision/standard Ethernet traffic on one physical switch feasible?

The GigE vision standard runs on on UDP/IP, which is layer 3 of the OSI model. Below layer 3, GigE data uses ethernet just like any other ethernet device

From the perspective of a switch, which is a layer 2 device, it simply sees ethernet traffic as ethernet traffic and does not care about data encapsulations in the frames at higher levels. Thus, from the point of view of the switch, there really isn’t much difference between your GigE Vision devices and your other ethernet devices. In fact, GigE Vision is specifically designed to use standard ethernet networks and to co-exist with other ethernet device. This is in contrast to something like EtherCAT which uses a different underlying network topology.

In other words, the only real consideration you have here is one of data rate, which is a consideration that we have already decided is not going to be an issue in your application.

Tl;dr, I can’t think of any reason that this won’t work and I’m sure we have other customers already doing something similar.