Re: A tiny almost sorta kinda nearly minimal perfect hash for a mac classifier?

[Dave Taht <dave.taht@gmail.com>]

On Mon, Nov 14, 2011 at 3:41 AM, Fred Baker <fred@cisco.com> wrote:
>
> On Nov 14, 2011, at 10:22 AM, Sean Conner wrote:
>
>>  Why not just use the lower N bits as the hash function?
>
> or
>
> unsigned macHash (unsigned long long  macAddressClone) {
>     return 0xFFF & (macAddressClone ^ (macAddressClone >> 12));
> }
>
> That allows you to keep different OUIs separated somewhat.

I should probably not have used 'arp' as an example, but suggested tcpdump.

Multicast and broadcast on 802.11 are 'special'. They are always
transmitted at the lowest rate possible (and eat up correspondingly
far more airtime), and in the case of power save mode, can be deferred
up to 200 ms, to wait for stations to be awake enough to 'hear' them.
So anything with the multicast mac bit set should end up dumped in a
special queue to manage that better.

Virtual interfaces on a given radio twiddle on the local mac bit and
then do arbitrary transforms elsewhere on the mac

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Dave Täht
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