# Question on 802.15.4 implementation **URL:** \ **Category:** GNU Radio\ **Created:** [May 28, 2014, 7:23pm UTC](https://www.ruby-forum.com/t/question-on-802-15-4-implementation/230057 "2014-05-28T19:23:32Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![jason\_sam](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/7993a0/32.png) [@jason\_sam](https://www.ruby-forum.com/u/jason_sam)\ **Post date:** [May 28, 2014, 7:23pm UTC](https://www.ruby-forum.com/t/question-on-802-15-4-implementation/230057/1 "2014-05-28T19:23:32Z")
Hi , I am trying to send a simple message between two USRPs using the new message passing interface in GNU Radio 3.7 over 802.15.4 implementation. I created a “message generator” which publishes a message to the “app in” port of 802.15.4. Similarly on the receiver side a “message consumer” gets the message from the “app out” port of 802.15.4, I see that the message on the receiver is getting dropped at the 15.4 MAC layer with the following debug message: mac.cc:mac\_in: pmt\_is\_pair mac.cc::mac\_in: data\_len = 30 CRC at Reception: 0 MAC: Dropping packet self routed I poked around mac.cc code a bit. It looks like the message received has the same mac id as the mac id of the receiver. It seems that the MAC layer does not use the _real_ MAC id, rather it generates mac id using “rand() % 100”. My understanding is that the receiver is also getting the same mac-id as the sender and hence dropping packet. Any idea how to fix the problem? Note that I am not using RIME stack for communication (as done by Bastian), but rather trying to send/receive message from/to MAC layer itself. thanks and regards -Anirud Anirudha “Anirud” Sahoo Advanced Network Technology Div. National Institute of Standards and Technology (NIST) 100 Bureau Drive, Gaithersburg, MD - 20878 Room - B230, bldg.- 222 Phone- 301-975-4439 ---
**Author:** ![SahooS\_Anirudha](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/a87d85/32.png) [@SahooS\_Anirudha](https://www.ruby-forum.com/u/SahooS_Anirudha)\ **Post date:** [May 29, 2014, 11:59am UTC](https://www.ruby-forum.com/t/question-on-802-15-4-implementation/230057/2 "2014-05-29T11:59:27Z")
Hi Anirud, On 28 May 2014, at 18:47, Sahoo, Anirudha [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > mac.cc:mac\_in: pmt\_is\_pair > mac.cc::mac\_in: data\_len = 30 > CRC at Reception: 0 > MAC: Dropping packet self routed > > I poked around mac.cc code a bit. It looks like the message received has the > same mac id as the mac id of the receiver. It seems that the MAC layer does not > use the _real_ MAC id, rather it generates mac id using rand() % 100. My > understanding is that the receiver is also getting the same mac-id as the sender > and hence dropping packet. > Any idea how to fix the problem? Which code are you using? I can neither find the debug output nor the rand() % 100 code. Also what do you mean with MAC id? Sequence number or MAC address? Best, Bastian ---
**Author:** ![SahooS\_Anirudha](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/a87d85/32.png) [@SahooS\_Anirudha](https://www.ruby-forum.com/u/SahooS_Anirudha)\ **Post date:** [May 30, 2014, 5:19pm UTC](https://www.ruby-forum.com/t/question-on-802-15-4-implementation/230057/3 "2014-05-30T17:19:53Z")
oops, I just found out that the code I have been working with, has been modified in-house. So, the debug message is coming from changes made to your code. Sorry about that. thanks and regards -Anirud Anirudha “Anirud” Sahoo National Institute of Standards and Technology Advanced Network Technologies Division 100 Bureau Drive, Stop 8920 Gaithersburg, MD 20899-8920