How to ping Host PC from Thread FTD?

RE: How to ping Host PC from Thread FTD?

senthil_kumar — Fri, 28 May 2021 10:06:41 GMT

Hi Jorgen

Sorry for replying the old case, I am using Raspberry pi as a Border router with NCP device nRF52840_dk and another one nRF52840_dk node as a CLI ftd node.

Here I have ping the new prefix with local PC and Google IPv4 DNS, But it is gave "Done" only. Otherwise nothing happened, and I can't connect to Google DNS IPv4. So now what can I have to do to setting the Google IPv4 DNS.

This is in CLI node side.

This is in OTBR Rpi side.

Thanks in advance.

Regards

Senthil

RE: How to ping Host PC from Thread FTD?

Jørgen Holmefjord — Wed, 20 May 2020 12:41:48 GMT

If you only has a 64 prefix on the border router, it is not possible to ping the nodes directly, as they do not have any global IPv6 address assigned to them. You could possibly do it with NAT46, but this is not setup in the border router image we provide.

If your ISP provides a larger prefix than 64, I think the best solution would be to get a router setup that supports assigning a /62 prefix to the border router. A router with OpenWRT or similar should be able to provide this.

RE: How to ping Host PC from Thread FTD?

thread_yoda — Wed, 20 May 2020 09:19:05 GMT

Hi Jørgen, many thanks ... that worked! I really appreciate it!

Is it possible to ping the thread FTD from the host PC? I read in one of the posts that it is not possible due to the border router being assigned the 64 prefix length.

RE: How to ping Host PC from Thread FTD?

Jørgen Holmefjord — Wed, 13 May 2020 16:12:53 GMT

I did a quick test on this today, and it is working fine on my setup. I'm able to ping both local PC and Google DNS from the CLI node with the changed prefix:

This was tested with a clean install of all device and the setups consist of a RPi 3 with the border router image, a nRF52840 DK with FTD UART NCP firmware connected to the RPi, and a nRF52840 DK with FTD UART CLI firmware, connected to the host PC. The following steps worked for me:

Modify /etc/tayga.conf by commenting out the well-known prefix and replacing it with the one from GitHub:
```
#prefix 64:ff9b::/96
prefix fd00:470:1f09:97c5::/96
```
Restart the tayga service:
```
sudo service tayga restart
```
Make sure that the CLI node is connected to the same network as the BR and that it has been assigned the "fd11:22::/64" address:
```
> ipaddr
fd11:22:0:0:e56f:48a6:cfee:553c
fdde:ad00:beef:0:0:ff:fe00:c800
fdde:ad00:beef:0:87a2:b565:781b:5ca9
fe80:0:0:0:2803:ad99:a600:828b
Done
```
If this is not the case, I power cycle the NCP board and run "sudo wpantund &" on the border router and check again. This usually solves this.

Test ping against local PC and Google IPv4 DNS to check that everything is working as expected, using the new prefix:

> ping fd00:470:1f09:97c5::192.168.1.124
> 16 bytes from fd00:470:1f09:97c5:0:0:c0a8:17c: icmp_seq=7 hlim=125 time=26ms
ping fd00:470:1f09:97c5::8.8.8.8
> 16 bytes from fd00:470:1f09:97c5:0:0:808:808: icmp_seq=8 hlim=50 time=46ms

As far as I know, link-local addresses are not reachable outside the Thread network (unless they can be reached with a single radio transmission - for instance the wpan0 interface of the border router), see IPv6 addressing in OpenThread documentation.

RE: How to ping Host PC from Thread FTD?

thread_yoda — Tue, 12 May 2020 19:58:57 GMT

Also, fundamentally does this mean I cannot have local LAN communication while at the same time have sensor to cloud interactions since I would need to change tayga.conf settings to support one or the other?

If that is true, then this seems restrictive. Is this a limitation of the border router software?

RE: How to ping Host PC from Thread FTD?

thread_yoda — Tue, 12 May 2020 19:43:19 GMT

Hi Jørgen,

Thanks for your quick response. I've attached the screenshot from the ifconfig output from the border router. Actually, it seems the prefix length is 64 so I have changed tayga to use

prefix 2600:8802:3001:36f0::/64

but still I get the same result as before.

Everyone tells the same thing, to change the prefix to something different than the global prefix, but that's what I did and it doesn't work. Would you be able to check this out on your side to see if it works? I think it would be straightforward for you to setup a local network and see how it should be setup. Then I can have confidence in the changes I am making with that working setup. Btw, I am using your default border router image with only these changes.

Also, I cannot ping using the link-local IPv6 address of the host PC. I thought at least that should work.

Thank you.

RE: How to ping Host PC from Thread FTD?

Jørgen Holmefjord — Tue, 12 May 2020 10:29:02 GMT

Hi,

Can you post the ifconfig output from your border router? If you do not have a /62 prefix address or lower on the border router, it will not be able to further subnet global IPv6 addresses to the Thread network (requires /64 prefix). Some routers refuse to provide larger prefix networks than /64.

In any case, you should be able to ping through the NAT64 interface, by modifying the tayga.conf file to use a different NAT64 prefix address from 64:ff9b::/96.

Best regards,
Jørgen