Queries in IPv6 of COAP server

[chirag]

I am trying to run the coap ipv6 based example code provided in nRF51 IOT SDK. I am using my Linux PC along with a BLE adapter as a BLE enabled router. I can successfully connect to the COAP_SERVER. But the problem is I cannot access the server with coap cu mozilla plugin. Whatever I do it says "Host is unreachable".

After the connection is established, following is the output of my ifconfig bt0:

bt0 Link encap:UNSPEC HWaddr 5C-F3-70-FF-FE-6D-E4-BD-00-00-00-00-00-00-00-00
inet6 addr: 2001:db8::5ef3:70ff:fe6d:e4bd/64 Scope:Global
inet6 addr: 2001:db8::7176:1801:a1b5:acd8/64 Scope:Global
inet6 addr: fe80::5ef3:70ff:fe6d:e4bd/64 Scope:Link
UP POINTOPOINT RUNNING MULTICAST MTU:1280 Metric:1
RX packets:1 errors:0 dropped:0 overruns:0 frame:0
TX packets:16 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1
RX bytes:28 (28.0 B) TX bytes:803 (803.0 B)

As can be observed from the output the MAC address of my dongle is 5C-F3-70-FF-FE-6D-E4-BD. So the first and the third inet6 addr (as can be observed from the output) has to be the global and link local address for my dongle. I understand the remaining inet6 addr (i.e. the second one) has to be of the COAP_SERVER. Now,

1. Is my understanding about inet6 addr of the COAP_SERVER correct?
2. If yes, then why does it not resemble in any way to the MAC Address of the COAP_SERVER ( 00:7D:43:62:4F:27 is the MAC address as observed during scanning)?
3. Assigned router prefix is : 2001:db8::/64
   MAC address is: 00:7D:43:62:4F:27
   So the manually generated global inet6 addr must be: 2001:db8::27d:43ff:fe62:4f27
   Is this correct?
4. I have used the address observed in output of ifconfig (the second inet6 addr) as well as the one generated(manually) from the MAC address in coap cu client, but none of it seems to work. What can be the reason?

Any help would be appreciated.

NOTE: I am running the coap cu plug in on same PC which is acting as BLE enabled router

Regards,
Chirag

[Petter Myhre]

Does "hcitool con" show that you are connected? Are you able to ping the kit(CoAP Server) with the link local address "ping6 -I bt0 fe80::27d:43ff:fe62:4f27" If you have configured RADVD to distribute prefix 2001:db8::/64 on the bt0 interface, and the MAC is 00:7D:43:62:4F:27. Then the global IPv6 address should be 2001:db8::27d:43ff:fe62:4f27. You may also need to assign the prefix to the bt0 interface with "ifconfig bt0 add 2001:db8::1/64". Are you able to ping the kit with the globale IPv6 address "ping6 2001:db8::27d:43ff:fe62:4f27"?

[narioinc89]

Hi Petter,

Thanks a bunch as your step with "assign prefix" to the bt0 interface was the missing part in the nordic iot tutorial. I got my nordic nfr52-dk board connect to the 6lowpan mqtt broker and send and subscribe to topics with ease after that. 

[Petter Myhre]

No problem. Glad you got it working :)