Talk:MAC address

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"TSS Live Calls". G4techTV. July 2, 2004.

Excellent work, but nothing on LAA, UAA or BIA and nothing on unicast, multicast, broadcast and functional addresses of frames! I've added all of these things, and some other articles - Ta bu shi da yu 12:18, 28 Jul 2004 (UTC)

KLC Consulting Frequent SPAMMER In This Section

It has been observed that any "How To Change MAC" external links added on this topic which refers directly or indirectly to KLC Consulting's website (http://www.klcconsulting.net/smac) which hosts the SMAC software, that the IP address of the anonymous poster is Class A IP address on network 68.0.0.0, 65.0.0.0 & on static IP 192.223.226.6. This has been observed since many months (you may check the history section for proofs). If you collect all the IP addresses then you would find that its clearly indicating that the SMAC commercial software is been advertised in this section and KLC Consulting is actively involved in adding the external links on regular intervals. —The preceding unsigned comment was added by 221.135.179.193 (talk) 06:02, 9 April 2007 (UTC).[reply]

Locally Assigned Addresses

The IEEE has assigned some OUIs with the 0x020000 bit set. Can anyone create and/or use a LAA OUI in MAC addresses on their LAN? --Jakllsch 19:37, 23 March 2006 (UTC)[reply]

The article's information about LAAs was previously wrong. I've updated the paragraph, but the diagram is still incorrect (it still shows the LA bit as second least sig, when it should be second most sig bit)if someone wants to get around to this. I trust information directly from IEEE to be the most accurate: http://standards.ieee.org/regauth/groupmac/tutorial.html. This should clear up some confusion about why it looked like the OUI and LAA address spaces were overlapping.131.107.0.73 21:37, 5 February 2007 (UTC)[reply]

Uniqueness

i want to ask one thing...when MAC address is unique for all networked machines...why do they need an IP address at all?

They are unique (well, almost) but the heirarchy under which they're organised is useless for routing. Your ethernet card's MAC address says "I'm a txp9000, made by XYZ Semiconductor". A machine on the other side of the world that wanted to send you a packet wouldn't know how to route that packet. By contrast, IP addresses are heirarchical by route (very very roughly). So if the remote machine sends a packet to 66.1.94.133 its router can look up a table that says "send all 66.1.x.x packets to router at 66.1.0.1". This way the remote router doesn't need to know the (impossibly long) list of exact IP addresses in your company or school - it only needs to know who is responsible for that "block" of IP addresses. It can do this because IP addresses are heirarchical by location in the wiring plan, whereas MAC addresses are only heirarchical by manufacturer (and don't tell you where on the network a given node is). -- John Fader (talk | contribs) 18:13, 22 Apr 2005 (UTC)

OS X

Can someone figure out if you can actually change a MAC address in OS X and update that section? Right now it looks quite silly. It says something like 'theoretically this should work, but i don't know nor am I motivated enough to check'

Burned in addresses

Currently, the article states

MAC addresses permanently attached to a product by the manufacturer are known as "burned-in addresses" (BIA) or sometimes as "Universally Administered Addresses" (UAA). The BIA can be overridden with a "Locally Administered Address" (LAA).

Does this mean that if one uses one of the methods to change the MAC address explained later in the article, one is using a LAA? Also, the article on burned-in address seems to disagree with the above statement; it states that there are two types of BIAs, namely UAAs and LAAs. AxelBoldt 22:24, 27 May 2005 (UTC)[reply]

No, it means that if one changes the MAC address, one is supposed to use an LAA instead of a UAA. I doubt it ever occurred to the designers of MAC-48 at the time that one would deliberately use the BIA of one station on a different station; after all, ‘they are just numbers and have no commercial significance’. 121a0012 01:52, May 28, 2005 (UTC)

Internal format of MAC

There is some formats of MAC addresses, I've read about them in "Computer Networks" by Andrew Tanenbaum.

Is it possible for a PC to loose its MAC address configuration permanently? What I mean is, my PC crashed during a thunderstorm, after it came back on I could no longer access my netwotk at home. Which is using DHCP. When I brought it to my office and connected it to my LAN I was able to connect. I also connected it directly into a device that is using DHCP and the PC recognized the connection. I then brought the PC home and reconnected it, in the hope that by some slim chance it would work, it did not. So that is why I am asking if it is possible for a PC to permanently loose a MAC address.

Myth about why 48 bits were chosen

For years I have been repeating something I heard somewhere: that the inventers of the Ethernet decided there should be enough MAC addresses to uniquely identify every 5-kilogram piece of the earth. Tonight I finally did the math for myself. (Thanks, Google, for programming the "mass of earth" into your calculator as a constant.) Google says the mass of the Earth / (2^48) = 2.12246221 × 10^10 kilograms. Not even close. The best source I found for the real story (using a quick Google search) is, "John Schoch, a former PARC researcher, ... notes that PARC ... gave [Ethernet] a ridiculously large 48-bit addressing scheme—far more than anyone imagined would be needed at the time." [1] <>< tbc 06:21, 20 December 2005 (UTC)[reply]

Confused About Terminology

Why is the term 'medium access control address' used by many sources (including the IEEE) but not used or referred to by this article? I'm confused as to the difference (if any) between this term and 'media access control address'. 216.166.159.185 06:14, 23 December 2005 (UTC) M. Glenn Lewis[reply]

That's a great question - When referring to the MAC address, there is no difference between media and medium access control address. Technically media is the plural form of medium but the IEEE standards appear to use media and medium for different parts of the standard. I'll research this soon and update the article as necessary to clarify. Sfisher 05:08, 25 December 2005 (UTC)[reply]

Found it; per IEEE standard 802 "Overview and Architecture" from 2001, medium and media are interchangable in the MAC abbrevation and that standard uses medium. Sfisher 20:22, 2 January 2006 (UTC)[reply]

Fixed finding MAC under Windows XP

The instructions for finding the MAC address under Windows XP recommended using arp -a, which shows the MAC of other machines on the Local Area Network. The command ipconfig/all shows the MAC address for all network devices. David Harbaugh

"Changing the MAC address" section

The whole section is not encyclopedic and should be removed. 121a0012 18:18, 7 May 2006 (UTC)[reply]

I agree; I think that maybe only the fact that it can be changed should be left in. — Preceding unsigned comment added by 68.6.58.5 (talk • contribs)

In the Wikipedia offical policy, it states that Wikipedia is not "an indiscriminate collection of information", specifically an instruction manual or how-to (title 8). This section could be construed as a how-to thereby violating section 8 of the guidelines. However, I find the information highly informative, relevant, and valuable whilst not largely violating the Wikipedia guidelines. Unless there is an external source that contains the same information presented here, and I have not found any, I propose it be kept. -Etienne 01:30, 12 July 2006 (UTC)[reply]

I've collected the MAC address changing information and posted it here. If you're happy with it, remove all the information and write a short section that MAC addresses can be changed and refer to this external link -Etienne 18:44, 19 July 2006 (UTC)[reply]

This is also an option Wikisource:Changing_MAC_addresses —The preceding unsigned comment was added by Etienne.navarro (talk • contribs) 19:42, 28 July 2006 (UTC).[reply]

What Wikisource Includes says, under What is excluded:

in the Original contributions section,

Works created by Wikisource users or otherwise not published in a verifiable, usually peer-reviewed forum do not belong at Wikisource. Wikisource is not a method for an author to get his or her works published and make them available to other people, nor is it a site to discover "new talent".

in the Evolving works section,

Wikisource's mission is to collect and preserve works in their original form. In light of this, works whose content is expected to constantly change over time (possibly for the purpose of keeping the work updated), to improve the content matter of what has already been published, or to make the text more comprehensive), are excluded from Wikisource's scope.

A few examples include

Open-ended texts where the author relies upon cooperative efforts by many contributors to finish and improve the work;
Compilations where there are many sources of a particular text, and/or the text is to be constantly updated as more relevant information is found and added;
Lists (see also below).

For more information about static texts, see Wikisource:Text integrity.

so I'm not sure that list belongs in Wikisource. Guy Harris 03:09, 29 July 2006 (UTC)[reply]

So does it belong in Wikipedia? --Etienne 02:32, 31 July 2006 (UTC)[reply]

``Changing the MAC address of the new interface will usually solve the problem. However, this action is generally frowned upon and if the service provider is able to detect that a MAC address is spoofed and prohibits spoofed MAC addresses, this method will not work."

Is it possible for a service provider to detect that a MAC address is being spoofed? I suspect not! The service provide may guess... For example, for months I use x megabytes of bandwidth per month. I then make a request using another MAC address (my router) which fails. Soon after I revert back to my old MAC address (spoofed by the router). My bandwitch usage subsequently increases to 2x megabytes a month, one could guess that I now have two machines behind the router, but this cannot be proven by the service provider.--Bah23 12:09, 26 January 2007 (UTC)[reply]

Required by the F.C.C.?

Every once in a while I hear some schpiel about network cards having MAC addresses is because the FCC requires it, usually claimed by people who know nothing about computers.

Googling around a few minutes all I see is similar hear-say.

I'm leaning toward the this-is-a-wives-tale opinion, but I thought I'd just get confirmation anyway. I see mention of the IEEE handing out MAC addresses on the Network card article, so maybe this is what people think of -- most laymen don't know what the IEEE is or that it even exists, are so maybe they got confused with the FCC considering it's a more "well-known" entity. --I am not good at running 08:48, 19 May 2006 (UTC)[reply]

Correct, the FCC has nothing to do with assigning MAC addresses. Network cards may have a separate FCC ID, but that is unrelated to the MAC address. Sfisher 05:41, 24 June 2006 (UTC)[reply]

Number of network devices built by a manufacturer

Because of the 3 octets OUI, a manufacturer can only assign 24 bits to a given network device. So, if a manufacturer builds more than 16 million network cards, it will have to stop producing network devices. 16 million is a big number, but not that many. Why have they reserved so many bits to identify a manufacturer? There are probably far less network device manufacturers than there are network devices built by big manufacturers. --Earendel 10:06, 15 June 2006 (UTC)[reply]

They can always get more. 121a0012 01:22, 16 June 2006 (UTC)[reply]

Yes, many companies have more than one OUI

ethernet address

"Ethernet address" redirects here. Please write a couple of words about it in the intro. `'mikka (t) 17:37, 17 July 2006 (UTC)[reply]

By the way, please clarify the entry in the "aether" disambiguation page: "in internet routing, the term ether is associated with hosts" What the heck is it? (Previously "hosts" was a redirect to "hosts file") `'mikka (t) 17:37, 17 July 2006 (UTC)[reply]

bits

The standard (IEEE 802) format for printing MAC-48 addresses in human-readable media is six groups of two hexadecimal digits, separated by hyphens (-) in transmission order, e.g. 01-23-45-67-89-ab. This form is also commonly used for EUI-64.

I think the red part should read This form, with eight groups of two hexadecimal digits instead of six, is commonly used for EUI-64, but I am hesitant to change it because I'm not familar with EUI-64 beyond what I have read here. --203.6.205.131 01:41, 31 July 2006 (UTC)[reply]

EUI-64, EUI-48 and MAC-48

Note: The IEEE now considers the label MAC-48 to be an obsolete term which was previously used to refer to a specific type of EUI-48 identifier used to address hardware interfaces within existing 802-based networking applications and should not be used in the future. Instead, the term EUI-48 should be used for this purpose.

IPv6 — one of the most prominent standards that uses EUI-64 — applies these rules inconsistently. Due to an error in the appendix to the specification of IPv6 addressing, it is standard practice to extend MAC-48 addresses (such as IEEE 802 MAC address) to EUI-64 using "FF-FE" rather than "FF-FF."

This is not an error then (IPv6's behaviour in regard to EUI-64)... because http://standards.ieee.org/regauth/oui/tutorials/EUI64.html says:

Restricted encapsulated values
To support encapsulation of EUI-48 and MAC-48 values within small subsets of the EUI-64 values, the first four digits of the manufacturer's extension identifier shall not be FFFF16 or FFFE16. Thus, the 64-bit values of the following form are never-assigned EUI-64 values: ccccccFFFEeeeeee16 (an EUI-48 extension) ccccccFFFFeeeeee16 (a MAC-48 extension)

So... if MAC-48 is a special case of EUI-48 and is obsolete, then it can be (consistently) interpreted as EUI-48 and thus converted to EUI-64 with FFFE inserted. This seems to be entirely correct.

Pavlix 14:04, 11 November 2006 (UTC)[reply]

sudo su

I'm fairly sure you don't want to do "sudo su"- you just want to do "sudo". 128.61.38.107

unique identifier?

In computer networking a Media Access Control address (MAC address) is a unique identifier attached to most network adapters (NICs).

Its only an unique identifier IF no one spoofs it.--Bah23 12:09, 26 January 2007 (UTC)[reply]

I agree. I therefore added a little "quasi" to this sentence. --Abdull 16:58, 15 May 2007 (UTC)[reply]

Link cleanup

I trimmed back the external links by removing all of the tools and how-to links on the basis of Wikipedia is not an instruction manual. I removed the Wireshark links because they were redundant with the remaining two.

I was prompted to look at the links by the back-and-forth placement of nthelp.com and klcconsulting.net links. The owner of klcconsulting.net (one of the editors) rightfully pointed out to me that the nthelp.com site just points to the klcconsulting.net site. The nthelp.com site states the material was copied, which is a copyright violation and even linking to such a site is not allowed by Wikipedia. My preference is to simply leave all of those links out of the article; they add little to understanding the topic. Please discuss new links here before adding them.

Finally, editors are reminded that the conflict of interest guideline indicates adding links to one's own site is to be avoided; suggest changes on the talk page instead and if neutral editors agree, let them place the link. ✤ JonHarder ^talk 17:55, 2 March 2007 (UTC)[reply]

Thank you, Jon. ~a (user • talk • contribs) 21:47, 4 March 2007 (UTC)[reply]

I approve of the continuing cleaning of how-to material from the article. ✤ JonHarder ^talk 02:16, 6 March 2007 (UTC)[reply]

I also approve of it. Guy Harris 03:11, 6 March 2007 (UTC)[reply]

Uppercase and lowercase

i've noticed some mac addresses use uppercase letter and some lowercase - does it matter if you type them in the correct case or not? Maybe this can be mentioned in the article - thanks —The preceding unsigned comment was added by Shakehandsman (talk • contribs).

Unclear sentence in introduction

"MAC addresses, unlike IP addresses and IPX addresses, are not divided into "host" and "network" portions, so a host cannot determine, from the MAC address of another host, whether that host is on the same layer 2 network segment as the sending host or a network segment bridged to that network segment and, if it's not, cannot determine the MAC address of a router that is on the same network segment as the sending host or a segment bridged to that network segment and that can help route the packet to the destination host."

I get lost reading this about halfway through, can it be clarified? 83.104.231.152 19:59, 17 June 2007 (UTC)[reply]

00:00:00:00:00

What does this address mean? I have read online that it usually denotes an error (usually because the MAC can't be read), but that it is also a valid address. 203.33.3.12 00:18, 27 June 2007 (UTC)[reply]

Unicast/multicast bit in picture?

There is a bit in the picture that can hold the value "unicast" or "multicast". Does anyone know what the difference is in this situation? Why set or clear that bit? Tommy 00:18, 29 July 2007 (UTC)[reply]

To quote IEEE Std 802-2002, "IEEE Standard for Local and Metropolitan Area Networks: Overview and Architecture":

The Individual/Group (I/G) address bit (LSB of octet 0) is used to identify the destination address as an individual address or a group address. If the I/G address bit is 0, it indicates that the address field contains an individual address. If this bit is 1, the address field contains a group address that identifies one or more (or all) stations connected to the LAN. The all-stations broadcast address is a special, predefined group address of all 1’s.

I.e., if the bit isn't set, the address is the address of a network adapter; if it is set, it's a multicast address or a broadcast address. Guy Harris 00:40, 29 July 2007 (UTC)[reply]

Thanks Guy. I updated the article according to your explanation. Tommy 12:38, 29 July 2007 (UTC)[reply]

wikisource link broken

it seems the Wikisource text on Changing MAC addresses has vanished.

deletion log there says it was transwikied to wikibooks, but i can't seem to find it there.

anyone got a proper link for it?

142.165.95.83 22:55, 20 September 2007 (UTC)[reply]