Date: Sun, 26 Aug 2001 22:37:04 -0700 From: Harry Putnam <reader@newsguy.com> To: freebsd-mobile@FreeBSD.ORG Subject: Re: Frustrating network problem - need diagnotic help Message-ID: <m11yly6p33.fsf@reader.newsguy.com> In-Reply-To: <200108262343.f7QNhuR11424@ptavv.es.net> ("Kevin Oberman"'s message of "Sun, 26 Aug 2001 16:43:56 -0700") References: <200108262343.f7QNhuR11424@ptavv.es.net>
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"Kevin Oberman" <oberman@es.net> writes: > For all of you who don't have a copy of 802.3 handy, there are two > special bits in a MAC address. They are the first two bits on the wire > in the MAC, but because of the bit ordering on the wire, these are the > last bits of the first byte of the MAC. How would you phrase this, speaking to a `network impaired' (dodo) person, please? Or at least maybe a diagram of the posted MAC as it relates to the items enumerated above. > The first bit is the "group address" bit. This means multicast or > broadcast. (Broadcast is simply a special case of multicast.) It > should NEVER be set in the source address, so the first octet must be > even. Ditto > The second bit the "locally administered" bit, indicating that the MAC > address is locally assigned and not always globally unique. Some > protocols like DECnet IV and Xerox PUP make use of this, but it is > pretty much unused these days. > > In any case, a MAC address with an odd first byte is clearly not legal > as a source address. Well, sounding like a perfect lamer here, I'm not sure I follow what this all means. Following bits, bytes, hexidecimal et al, confuses me greatly. Can you offer a guess as to what this all means for the posted MAC: 01:d4:ff:03:00:20? Sounds as if it is a patent dud, what with starting like `01'. Is that true? What does one do to correct bogus recognition? Or, when you say `source address' does that not apply to the address revealed with `ifconfig ed0'? To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-mobile" in the body of the message
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