About forwarding information through the router

RE: About forwarding information through the router

Marte Myrvold — Thu, 16 Feb 2023 10:35:40 GMT

Hi,

I need to clear up some things about Thread. Thread in itself is a transport layer that implements IPv6. Technically, you do not send messages directly over Thread; you need to use an application to communicate. The most basic applications are Ping, UDP, and TCP. The picture shows the OpenThread architecture:

This runs on top of the IEEE 802.15.4 physical layer (PHY). A border router provides connectivity from IEEE 802.15.4 networks to networks on other physical layers (for example, Wi-Fi).

CoAP, which is used in these samples, is a web transfer protocol that runs over UDP.
What you need to do to send messages to other devices that are not on the Thread network is to send messages over, for example, UDP. For example, you can look at Socket Echo Client and Socket Echo Server. These can be built with Thread support by setting overlay-ot.conf as overlay configuration.

We have two webinars about Thread that I strongly recommend watching:
https://webinars.nordicsemi.com/introduction-to-thread-networking-4
https://webinars.nordicsemi.com/developing-thread-products-with-nrf-1

[quote user="caidehen"]1. If I want to generate a message in the router and forward it to the non-thread network through the intermediate router, how should I generate this message? It doesn't seem to be generated by pressing keys[/quote]

This needs to be implemented in the application. Look at the Socket Echo samples I link to above.

[quote user="caidehen"]2、You mean that the message generated by pressing the key seems to be uploaded to the non-thread network through the server only after it is received by the server. What should I do on the server? Or don't do any operation. If necessary, which api should I add to upload the received key data to the non-thread network？[/quote]

No. The server will not forward the command to a non-Thread network since the command is not meant to be sent to another device that is not on the Thread network. The server is the destination of the command.

[quote user="caidehen"]3. Is it possible for me to upload data to non-thread network data monitoring through raspberry pie as long as I establish a border route?[/quote]

You can send messages to Raspberry Pi if you run a server on the Pi that can receive the messages.

[quote user="caidehen"]This means that key information can be forwarded by the intermediate router. Isn't the process of forwarding keystroke information just the process of receiving and sending? [/quote]

Yes. The router receives the message. If the message's destination is this router, then it will handle the message. If it is not the destination, then it will forward the message.

[quote user="caidehen"]I'm a little confused about this point. Why does the router in the middle not forward when there is no server? Why can the router in the middle forward when there has a server ？[/quote]

My answer was in response to this:

If I burn all the above four devices as clients, they will still decide the leader and their respective router. Then when I press the button 2 of any development board, will all the information sent out at this time be summarized to the leader?

This has nothing to do with whether the middle router will forward. All the clients will receive the message, see that they are not the message's destination, then forward the message and not handle it further. This is true for both the routers and the leader. The leader will not handle this message any differently than the routers, as it is not the message's destination.

[quote user="caidehen"]My understanding is that whether there is no server, the router（client） will receive and forward the keystroke information, but the router（client） has no corresponding action to execute ， right？[/quote]

Correct.

Best regards,

Marte

RE: About forwarding information through the router

caidehen — Thu, 16 Feb 2023 00:44:54 GMT

Dear experts Marte Myrvold

you said "Yes, as long as the devices are router devices and the distances between the devices are large enough." This means that key information can be forwarded by the intermediate router. Isn't the process of forwarding keystroke information just the process of receiving and sending?

you also said" If there are no server devices, then there are no devices to receive the command. "

I'm a little confused about this point. Why does the router in the middle not forward when there is no server? Why can the router in the middle forward when there has a server ？

My understanding is that whether there is no server, the router（client） will receive and forward the keystroke information, but the router（client） has no corresponding action to execute ， right？

RE: About forwarding information through the router

caidehen — Wed, 15 Feb 2023 16:17:46 GMT

Dear experts

It's a great honor to receive your patient answer. Thank you very much

Please allow me to ask another question. I'm going to have a rest

1. If I want to generate a message in the router and forward it to the non-thread network through the intermediate router, how should I generate this message? It doesn't seem to be generated by pressing keys

2、You mean that the message generated by pressing the key seems to be uploaded to the non-thread network through the server only after it is received by the server. What should I do on the server? Or don't do any operation. If necessary, which api should I add to upload the received key data to the non-thread network？

3. Is it possible for me to upload data to non-thread network data monitoring through raspberry pie as long as I establish a border route?

Thank you again and wish you a pleasant work

RE: About forwarding information through the router

Marte Myrvold — Wed, 15 Feb 2023 14:56:04 GMT

Hi,

[quote user="caidehen"]1、nRF Sniffer for 802.15.4 It seems that this sniffer can only be applied to nrf52840dk. I only have nrf52833dk, so it seems impossible to achieve. i've followed this procedure before and it hasn't worked ， is there any other sniffing method?[/quote]

Not using our sniffer, it only supports nRF52840 DK and dongle.

[quote user="caidehen"]2、If I burn all the above four devices as clients, they will still decide the leader and their respective router. Then when I press the button 2 of any development board, will all the information sent out at this time be summarized to the leader?[/quote]

No. Pressing button 2 on the client will send a light on/off command to server devices. If there are no server devices, then there are no devices to receive the command. The leader role does not have anything to do with this. A Thread leader is simply the router in the network responsible for managing the other routers (such as assigning router IDs).

[quote user="caidehen"]3、If you add a boundary route to the network at this time （router1's key 2 is pressed to send the message）then the leader is going to send this key information to the network is that right?[/quote]

The other routers can communicate with the border router, not just the leader. There is a picture showing an example of what a Thread network with a border router might look like in Node Roles and Types:

The messages will be sent through the border router if you send information to a non-Thread network (such as Wi-Fi). However, that is not the case here. The client sends the light on/off command to Thread CoAP servers. As before, if there are no servers on the network, there are no devices to receive the command. The client will not suddenly send the light on/off command to a non-Thread network when no servers receive the command.

Best regards,
Marte

RE: About forwarding information through the router

caidehen — Wed, 15 Feb 2023 12:20:05 GMT

Dear Professor Marte Myrvold

Thank you very much for your patient reply，but But there are still some problems
1、nRF Sniffer for 802.15.4 It seems that this sniffer can only be applied to nrf52840dk. I only have nrf52833dk, so it seems impossible to achieve. i've followed this procedure before and it hasn't worked ， is there any other sniffing method?
2、If I burn all the above four devices as clients, they will still decide the leader and their respective router. Then when I press the button 2 of any development board, will all the information sent out at this time be summarized to the leader?
3、If you add a boundary route to the network at this time （router1's key 2 is pressed to send the message）then the leader is going to send this key information to the network is that right?

RE: About forwarding information through the router

Marte Myrvold — Wed, 15 Feb 2023 09:33:28 GMT

Hi,

[quote user="caidehen"]can I understand that as long as I burn nrf52833dk into the client or server program, I don't need to consider the whole networking process and the role change will be automatically completed?[/quote]

That is correct. Router selection happens automatically. If there is a need for more routers, one of the router-eligible end devices (REEDs) will automatically be promoted from child to router.

[quote user="caidehen"]As you said, if the four devices are far enough apart and placed in a straight line, then the router1 presses the button 2 to send data, which will be forwarded by router2 and then router3 and finally to the leader (server), right?[/quote]

Yes, as long as the devices are router devices and the distances between the devices are large enough.

[quote user="caidehen"]I wonder why I pressed the key on router1 at this point. 2 still broadcasts the message to the rightmost burning server development board (led4 lights on or off) but why not to the leader? [/quote]

Are you asking why it did not route the message through the leader or why the final destination was the server? If router 2 sent the message directly to the server without routing it through the leader, it was because that was the optimal path. Regarding the latter, the server is the destination because of how the example works. The clients will send the message to a server. The leader role is irrelevant here.

[quote user="caidehen"] how should I monitor the data transfer in between ？[/quote]

You can look at the network traffic in a sniffer log. See nRF Sniffer for 802.15.4 for how to set up and use our 802.15.4 sniffer.

[quote user="caidehen"]who is the data ultimately going to?[/quote]

It is going to the server.

Best regards,
Marte

RE: About forwarding information through the router

caidehen — Tue, 14 Feb 2023 15:38:02 GMT

1、Dear Professor Marte Myrvold, can I understand that as long as I burn nrf52833dk into the client or server program, I don't need to consider the whole networking process and the role change will be automatically completed?

2、As you said, if the four devices are far enough apart and placed in a straight line, then the router1 presses the button 2 to send data, which will be forwarded by router2 and then router3 and finally to the leader (server), right?

3、In the process of retesting, I found that when I powered off the leader (be burned into the server program), the remaining three (burned into the client program) automatically decided to create a new leader ，he original router3 is elected leader (I understood this principle after reading information). When I powered on the development board of the burned server program again, which changed the itself to a router. as shown in the following figure

I wonder why I pressed the key on router1 at this point. 2 still broadcasts the message to the rightmost burning server development board (led4 lights on or off) but why not to the leader? Or am I not monitoring the data？ how should I monitor the data transfer in between ？ who is the data ultimately going to?

RE: About forwarding information through the router

caidehen — Tue, 14 Feb 2023 14:35:22 GMT

Just like the yellow link in the picture below, how does the router transmit?

How can I measure the router forwarding process?

RE: About forwarding information through the router

Marte Myrvold — Tue, 14 Feb 2023 14:33:54 GMT

Hi,

[quote user=""]Doesn't my router have the function of data forwarding?[/quote]

The routers have routing and message-forwarding capabilities.
In Thread, the routers will determine the best next hop for a message based on neighbor link quality and path cost. Based on this, they will choose the cheapest and most optimal path to the destination. In your case, this means that router 1 found that the cheapest path to the leader is to send the message directly through the leader. This will often be the case if the devices are close by and without disturbances between them, as it is cheaper to send the message directly than through additional devices.

Since you want to force the devices to route the message from 1 -> 2 -> 3 -> leader, you need to ensure that the devices are far apart. You must make it cheaper to route the message through the closest neighbor than directly to the destination, possibly putting the devices that should not communicate directly out of range of each other.

[quote user="caidehen"]And what does the yellow print failure mean?[/quote]

Failed to process Link Request: InvalidState
As you see on the line above in the log, the device is currently a child.

Link requests are sent to routers. Since the device is a child and not a router when it receives the link request, it is in an invalid state to process the link request.

Failed to process UDP: Duplicated
The device received a duplicate UDP message, so the duplicate will not be processed.

I recommend reading up on device roles, see Node Roles and Types, and Router Selection.

Best regards,
Marte

RE: About forwarding information through the router

caidehen — Tue, 14 Feb 2023 08:55:00 GMT

I opened four PuttYs for listening and status query, and found that the router did not forward messages And what does the yellow print failure mean?