Hi Guido, Type and length fields in section 8 are defined in Neighbor Discovery. The amount of ND options may not be that huge even in future extensions, but compressing thiese fields is not in the charter for now.
The length is in units of 8 bytes. For example, over Ethernet, length would be 1 (type+length+6bytes Ethernet address->8bytes) With a 16-bit address, you will need 4 bytes (type + length + 2 bytes address), plus 4 bytes of padding to reach a multiple of 8, hence total is 8, length field is 1 With a 64-bit address, you will need 10 bytes (type + length + 8 bytes address), plus 6 bytes of padding, total is 16, length field is 2. Best, Julien -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Guido Moritz Sent: jeudi 29 janvier 2009 15:41 To: [email protected] Subject: [6lowpan] Questions about RFC 4944 Hello, I just finished going through RFC4944 and I have three questions left, I cannot understand. Maybe you can help me with that and provide me with a better understanding. 1. Section 8 The type field is 8 bit. Why is it so big? The length field is units of 8: I understand it as multiples of 8-bit. Why means value 1 16-bit and value 2 64-bit addresses? It should be 8-bit and 16-bit with the values 1 and 1?! 2. Section 9 What is the reason, that mulitcast address mapping only has to be supported in mesh-enabled networks? What is the concept behind that. Thank you for your answers. Kind Regards Guido Moritz ------------------------- Dipl. Ing. Guido Moritz Universitaet Rostock, Fakultaet f. Informatik und Elektrotechnik Institut f. Angewandte Mikroelektronik und Datentechnik University of Rostock, Department of CS and EE Institute of Applied Microelectronics and Computer Engineering Richard-Wagner Str. 31, 18119 Rostock-Warnemuende Phone: +49 (0)381 498 - 7269 http://www.imd.uni-rostock.de http://www.aal-rostock.de _______________________________________________ 6lowpan mailing list [email protected] https://www.ietf.org/mailman/listinfo/6lowpan _______________________________________________ 6lowpan mailing list [email protected] https://www.ietf.org/mailman/listinfo/6lowpan
