Extended MAC to IPv6 addrr

[nandra]

Hello, I've go through ot cli interface and I can setup 3 nodes without issue. For reaching node I can run ipaddr command to see address and then use ping or other to communicate with node. Is there simple way to do such thing programatically? I know there exists SRP server/client but maybe exist something else? Can I somehow reuse router table command output? Seems Extended MAC is somehow similar to node IPaddr? Thanks for any pointers.

[abtink]

@nandra, here's a suggestion for you to consider: You can construct an RLOC IPv6 address for a Thread device if you know its RLOC16 (short MAC address). This RLOC IPv6 address can then be used to communicate with the device. This can help https://openthread.io/guides/thread-primer/ipv6-addressing

[abtink]

fd49:4239:dd86:28:0:ff:fe00:9800 is its RLOC address. Note the pattern, <mesh-local prefix>:0:ff:fe00:<rlco16>.

You can construct RLOC addresses of other devices if you know their RLOC16, e.g. for the node with RLOC16 of 0x1000 its RLOC Ipv6 address will be fd49:4239:dd86:28:0:ff:fe00:1000

[nandra]

How to get mesh-local-prefix please? Also according this: https://openthread.io/guides/thread-primer/ipv6-addressing RLOC address shouldn't be used by applications and I would like to use IP address for communication between nodes? Thanks.

[jwhui]

The Mesh Local Prefix is configured as part of the Active Operational Dataset.

• CLI for managing Operational Datasets: https://openthread.io/reference/cli/concepts/dataset
• CLI for directly accessing Mesh Local Prefix: https://openthread.io/reference/cli/commands#prefix_meshlocal

As for whether the RLOC can be directly used, it really depends on what your intent is. The RLOC for a given device is derived based on the topology, so it can change as the Thread network topology changes.

If you're looking for a more general way to discover services and resolve IPv6 addresses, then DNS-SD is the suggested method, which is consistent with how many existing IP-based devices operate today.

[nandra]

@jwhui ok I read the comments and now I understand better. But would be possible somehow to get on one node ML-EID address from other node (without using srp etc). basically I want to communicate with nodes so need to somehow know their ip address. When node is added to network isn't information about ML-EID published somewhere? Thanks.

[abtink]

When node is added to network isn't information about ML-EID published somewhere? Thanks

What you are asking is what DNS-SD (SRP) does :)...

Device registers its service(s) and address(es) with an SRP server, then other device can query the server to discover the device and learn its address(es).