“All Groups” multicast diagnostics request September 2008 doc.: IEEE 802.11-08/0963r1 September 2008 “All Groups” multicast diagnostics request Date: 2008-08-07 Authors: Alex Ashley, NDS Ltd Alex Ashley, NDS Ltd

September 2008 doc.: IEEE 802.11-08/0963r1 September 2008 Abstract CID 301 in LB123 was resolved by adding a “magic” value of 7F-FF-FF-FF-FF-FE to indicate “any multicast frame”. However, this value is a legitimate multicast group address, so it needs to be changed. 301 There is no ability to make a wildcard multicast MAC address request - "i..e report on all multicast groups you participate in" [This is a "lost" D1.0 comment] Alex Ashley, NDS Ltd Alex Ashley, NDS Ltd

IEEE 802 MAC Address Format September 2008 IEEE 802 MAC Address Format [begin placing presentation body text here] Alex Ashley, NDS Ltd

Hexadecimal Representation September 2008 Hexadecimal Representation 3.1.8 hexadecimal representation: The representation of a sequence of octet values in which the values of the individual octets are displayed in order from left to right, with each octet value represented as a two-digit hexadecimal numeral, and with the resulting pairs of hexadecimal digits separated by hyphens. The order of the hexadecimal digits in each pair, and the mapping between the hexadecimal digits and the bits of the octet value, are derived by interpreting the bits of the octet value as a binary numeral using the normal mathematical rules for digit significance. Alex Ashley, NDS Ltd

So 7F-FF-FF-FF-FF-FE is invalid because? September 2008 So 7F-FF-FF-FF-FF-FE is invalid because? The LSB (bit 0) of octet zero is 1 This means it is a group MAC address Bit 1 of octet zero is 1 This means that it is locally administered So the address we chose could in theory be used as a valid group MAC address Alex Ashley, NDS Ltd

September 2008 Three Options We need an address with the group bit reset, because this will never be confused with a multicast group 7E-FF-FF-FF-FF-7E Pro: A palindrome that is robust to bit ordering confusions Con: A slightly more complex compare 00-00-00-00-00-00 Pro: A very simple compare Con: OUI 000000 registered to Xerox Undefined (any address with LSB bit zero) Pro: A simple compare Con: No fixed value makes packet snoop debugging much harder Alex Ashley, NDS Ltd

Straw Poll Do you prefer option 1, 2 or 3 ? September 2008 Alex Ashley, NDS Ltd

September 2008 Motion 1 Move the TGv editor to replace the value “7F-FF-FF-FF-FF-FE” in sub-clause 7.3.2.21.10a of the TGv draft with “7E-FF-FF-FF-FF-7E” Alex Ashley, NDS Ltd

September 2008 Motion 2 Move the TGv editor to replace the value “7F-FF-FF-FF-FF-FE” in sub-clause 7.3.2.21.10a of the TGv draft with “00-00-00-00-00-00” Alex Ashley, NDS Ltd

Motion 3 Move the TGv editor to replace: September 2008 Motion 3 Move the TGv editor to replace: “The Group MAC Address field can be set to 7F-FF-FF-FF-FF-FE to indicate that all group addressed frames, apart from the broadcast MAC address, are requested.” in sub-clause 7.3.2.21.10a of the TGv draft with: “A Group MAC Address field with the LSB of the first octet set to zero indicates that all group addressed frames, apart from the broadcast MAC address, are requested.” Alex Ashley, NDS Ltd

September 2008 References IEEE Std 802-2001 - IEEE Standard for Local and Metropolitan Area Networks: Overview and Architecture Alex Ashley, NDS Ltd