https://devzone.nordicsemi.com/f/nordic-q-a/10979/multicast-support-for-coap-in-nordic-nrf51Hi, I am using Nordic nrf51 DK board with soft device s1xx-iot-prototype2_softdevice.hex and application program as CoAP server from nRF_IoT_Examples\0.8.0\coap\ipv6\server. with the above configuration, i am able to establish ble connection from linuxen-USTelligent Community 13Sun, 10 Jan 2016 04:22:53 GMThttps://devzone.nordicsemi.com/thread/41049?ContentTypeID=1Sun, 10 Jan 2016 04:22:53 GMT137ad170-7792-4731-bb38-c0d22fbe4515:96f3a00d-9249-4d59-ae7a-0d71c5f2ac25Sandeep<p>Hi Petter, Multicast is needed for service discovery. IoTivity sends a multicast packet by default to &quot;All CoAP Nodes&quot; multicast address. Since, there is no multicast support in nordic nRF51 IoT SDK, i tried with unicast using firefox Copper plugin from linux host (to which nRF51 is paired) using link-local address and global address(with radvd enabled). But, this didn&#39;t work. Later, i tried with libcoap package, and this worked for me. I am able to communicate to nRF51 using CoAP protocol with unicast from linux host which is paired to nRF51. I am trying to understand IoTivity framework in detail whether multicast is mandatory.</p> <p>Thanks, Sandeep</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/41048?ContentTypeID=1Tue, 22 Dec 2015 13:36:31 GMT137ad170-7792-4731-bb38-c0d22fbe4515:51976728-e0a5-4e96-bd03-a6b30b75f579Petter Myhre<p>I don&#39;t understand what multicast has to do with this, it seems you are trying to do unicast; between the nRF51 and Copper. Have you set up RADVD in Linux? Are you using a global IPv6 address or a local? Are you using a local prefix? FE80? You need a global prefix to send IPv6 packets between interfaces, for example BT0 and ETH0? Where are you running Copper?</p><div style="clear:both;"></div>