From owner-freebsd-mobile Sun Aug 26 16:44: 8 2001 Delivered-To: freebsd-mobile@freebsd.org Received: from ptavv.es.net (ptavv.es.net [198.128.4.29]) by hub.freebsd.org (Postfix) with ESMTP id 6EB9937B407 for ; Sun, 26 Aug 2001 16:44:05 -0700 (PDT) (envelope-from oberman@ptavv.es.net) Received: from ptavv.es.net (localhost [127.0.0.1]) by ptavv.es.net (8.10.1/8.10.1) with ESMTP id f7QNhuR11424; Sun, 26 Aug 2001 16:43:56 -0700 (PDT) Message-Id: <200108262343.f7QNhuR11424@ptavv.es.net> To: Brian Reichert Cc: Harry Putnam , freebsd-mobile@FreeBSD.ORG Subject: Re: Frustrating network problem - need diagnotic help In-reply-to: Your message of "Sun, 26 Aug 2001 13:03:47 EDT." <20010826130347.A81961@numachi.com> Date: Sun, 26 Aug 2001 16:43:56 -0700 From: "Kevin Oberman" Sender: owner-freebsd-mobile@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org > Date: Sun, 26 Aug 2001 13:03:47 -0400 > From: Brian Reichert > Sender: owner-freebsd-mobile@FreeBSD.ORG > > On Sun, Aug 26, 2001 at 06:55:38AM -0700, Harry Putnam wrote: > > How does one tell if it is a bogus MAC address? > > I initially had to cheat, and look at how Windows probed that card, > for in that OS, it worked. Ultimately, I researched the fields of > the MAC address and found that: > > - From your supplied URL, the vendor is [Toshiba America] > [3COM/NoteWorthy 56K Modem] > > Comparing the first three bytes or your MAC 01:d4:ff:03:00:20 against any > MAC vendor list implies a mismatch: > > > > > - Although, for the life of me I can't reaconstruct the research, > I recall learning that that list bit of the MAC address must be > '1', otherwise, it's interpreted as a multicast address. (Which > only makes sense in a destination address, not a source address, > which it what your card's MAC will be used for.) > > > What do you mean by > > `certain' above? There were some tcp connections you could not make? > > I whined to -mobile and -isp, with some feedback. Look for these > subjects: > > 'linksys vs cisco' > 'LinkSys NP100 vs the universe' > > No solutions are discussed, but I go into great detail of the > sypmtoms I was seeing in different environments. > > In my case, though, it came down to a buggy ed driver in FreeBSD > 4.0-RELEASE, when 4.1 came out I uprgaded, and voila! I had a > working NIC. 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. 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. 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. R. Kevin Oberman, Network Engineer Energy Sciences Network (ESnet) Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab) E-mail: oberman@es.net Phone: +1 510 486-8634 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-mobile" in the body of the message