Hello José For 1) I agree that there is no need to encapsulate the DIO. The only message that is not hop by hop is the non-storing DAO, and since it is supposed to be contained in a DODAG, it does not need an extra encapsulation or routing header, but it requires a RPL option.
Cheers, Pascal From: 6tisch [mailto:[email protected]] On Behalf Of José Ángel Miranda Sent: mercredi 1 juillet 2015 09:30 To: Jacopo Soffritti; [email protected] Subject: [6tisch] DR DIO message format from GD. We found some doubts when reading the DIO message sent by the DODAG Root from the current GD version: 1. The DIO message is encoded with the IPv6 in IPv6 tunneling header. Is it necessary ? The minimal-10 draft at section 9.2 states: " ... In the case that the packets formed at the LLN need to cross through intermediate routers, these MUST obey to the IP in IP encapsulation requirement... " ; since DIO messages do not cross any router, but are sent hop by hop by every RPL routing node why do we need to encapsulate them with this additional header and " waste " more than 30 bytes of payload in a low power application like WSN ? 2. The DIO Base byte number 5 ( G | 0 | MOP | Prf ) is seto to " 0xB8 " ; this means G = 1 , MOP = 7 , Prf = 0 ( this bug has been already detected by 6TiSCH ). The RPL Standard at section 6.3.1 defines as assigned modes of operation only numbers 0 to 3, so MOP = 7 is not admitted by the standard, thus a node that receives such DIO message will certainly discard it since this mode of operation is a non-standard one. 3. The DIO message comes without any DIO Option and advertises a rank of "0x0000" in bytes 3 and 4 of the DIO base. The RPL standard at section 8.2.2.2 says " ... A DODAG root MUST advertise a Rank of ROOT_RANK ... " , and defines ROOT_RANK at point 17 as "... This is the Rank for a DODAG root. ROOT_RANK has a value of MinHopRankIncrease (as advertised by the DODAG root) ... " . The minimal-10 draft at section 9.1.1 states: "... MinHopRankIncrease: the MinHopRankIncrease is set to the fixed constant DEFAULT_MIN_HOP_rank_increment [RFC6550]. DEFAULT_MIN_HOP_rank_increment has a value of 256. " Given that, shouldn't the rank of the DIO message be equal to MinHopRankIncrease instead than zero ? Moreover, don't you find convenient to insert the " DODAG configuration option" in the DIO message, in order to let nodes know how the DODAG works and be configured accordingly ? You can find attached a screenshot from the DR's DIO message reception. ------------------------------------------ Jose A. Miranda Calero Embedded Software Engineer Kirale Technologies S.L. Logroño - Spain tel: +34941578578 [https://docs.google.com/a/kirale.com/uc?id=0B2YgpSi01ToPSHljY2FMaFluNlk&export=download]
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