Talk:MAC address/Archive 1

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The following discussion is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Comments from User:Ta bu shi da yu

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)

Fibre Channel uses EUI64 ?!

I think FC uses 64-bit addresses. Can anyone check that and edit the page as nessesery ?

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 ( which hosts the SMAC software, that the IP address of the anonymous poster is Class A IP address on network, & on static IP 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 (talk) 06:02, 9 April 2007 (UTC).

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)

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: This should clear up some confusion about why it looked like the OUI and LAA address spaces were overlapping. 21:37, 5 February 2007 (UTC)

The IEEE tutorial article states: "The U/L bit indicates whether the MAC address has been universally or locally assigned." IMHO this does not state at all if 0=locally or 1=locally. (talk) 14:28, 12 September 2008 (UTC)

CAUTION! You should read the IEEE tutorial more carefully since they use a Big-Endian Byte Order with a Little Endian Bit Order! Quoting the IEEE tutorial : "The Individual/Group address bit is the least significant bit." At least this should be clear to everybody. So in my opinion the picture in the article is correct but only uses a different bit order! (talk) 13:37, 15 September 2008 (UTC)


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 its router can look up a table that says "send all 66.1.x.x packets to router at". 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)

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)

They can always get more. 121a0012 01:22, 16 June 2006 (UTC)
Yes, many companies have more than one OUI


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)

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)

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)

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'. 06:14, 23 December 2005 (UTC) M. Glenn Lewis

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)
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)

"Changing the MAC address" section

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

I agree; I think that maybe only the fact that it can be changed should be left in. —Preceding unsigned comment added by (talkcontribs)
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)
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)
This is also an option Wikisource:Changing_MAC_addresses —The preceding unsigned comment was added by Etienne.navarro (talkcontribs) 19:42, 28 July 2006 (UTC).
What Wikisource Includes says, under What is excluded:
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".
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
  1. Open-ended texts where the author relies upon cooperative efforts by many contributors to finish and improve the work;
  2. 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;
  3. 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)
So does it belong in Wikipedia? --Etienne 02:32, 31 July 2006 (UTC)

``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)

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)

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)

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)

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)


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. -- 01:41, 31 July 2006 (UTC)

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 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)

sudo su

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

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)

I agree. I therefore added a little "quasi" to this sentence. --Abdull 16:58, 15 May 2007 (UTC)
I disagree with quasi. It makes it sound as if there could be a legitimate duplicate mac address. It is infeasible to have a legitimate duplicate. While I agree you could have a duplicate thanks to mac spoofing, a little clarification on this point is necessary. —Preceding unsigned comment added by (talk) 05:21, 20 February 2008 (UTC)

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 and links. The owner of (one of the editors) rightfully pointed out to me that the site just points to the site. The 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)

Thank you, Jon. ~a (usertalkcontribs) 21:47, 4 March 2007 (UTC)
I approve of the continuing cleaning of how-to material from the article. JonHarder talk 02:16, 6 March 2007 (UTC)
I also approve of it. Guy Harris 03:11, 6 March 2007 (UTC)

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 (talkcontribs).

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? 19:59, 17 June 2007 (UTC)


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. 00:18, 27 June 2007 (UTC)

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)

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)

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

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? 22:55, 20 September 2007 (UTC)

Nokia and naming

Nokia is officially calling the MAC address a "WLAN number". It uses the number as a unique identifier on its Nokia 770 (and presumably its other internet tablets). Whenever I need to engage in some kind of official communication about my N770, Nokia demands my WLAN number (see for more info). Is that usage sufficient to update the first line (also known as...)? samwaltz (talk) 19:11, 24 December 2007 (UTC)

Do you have a link to a reputable/reliable source? ~a (usertalkcontribs) 21:41, 24 December 2007 (UTC)
Aside from the address at, given above? I'll do a check, and post a few more in the morning. I would, however, think that would be a sufficiently notable source. samwaltz (talk) 08:34, 31 December 2007 (UTC)

I/G U/LMistake

Corrected as per IEEE: IEEE (talk) 21:20, 19 October 2008 (UTC)


can someone say something about the privacy implications of MAC addresses? Can they be seen b other net users? Does that matter? Ca they be linked to individuals etc? It's unclear from this article what they are for. —Preceding unsigned comment added by (talk) 16:35, 25 August 2008 (UTC)

They can only be seen by people on the same physical network. In other words, when stuff hits a router, people on the one side can not see the MACs of those on the other side. Of course this is baring any intrusion that may be taking place. It does not really matter if other people see them though. As for being linked to individuals I think you mean can anyone say who uses a particular MAC address... Short answer, no. However, if a company who sells you a device logs the MAC along with their sale record to you they could potentially know (but who is to say you haven't sold it to someone else yourself). As for what they are used for: MAC addresses is what computers use to talk to each other. Many people think its simply just IP, but in reality an IP address is basically just an alias for your MAC address. Say you have two computers on the same network with the IPs of and In order for them to communicate, they listen to the data line to see packets from MACs they do not know. When they see one, they secretly record the IP associated with that packet and log it in their ARP (Address Resolution Protocol) table. If they have not yet figured out what MAC belongs to an IP they send out an ARP request. Basically this request just says: "Who is". would then reply with "I'm and my MAC is bla bla". Then that device can now communicate with the other device using the MAC address.
To get just a little more technical, MAC addresses work on layer 2 of the OSI model. Layer two is the data link layer. This is the layer that computers actually make connections with each other and they do so with the MAC address. Layer 3 is the network layer in which IP resides. To sum it up, MAC addresses are used to make the actual direct connection and IP is used to determine the network on which a computer (or MAC address) resides. Fortunatly, computers on different networks do not need to know the MAC address of computers on other networks, even when they are communicating with each other. This is because they are communicating over a network (Layer 3) instead of directly (layer 2).
Hope that helps. Jwjkp (talk) 13:27, 23 December 2008 (UTC)

Globally Unique (OUI Enforced) Bit

Can anyone explain why neither XP nor Vista seems to set the Globally Unique (OUI Enforced) Bit (bit 2 of the first byte) when they generate an address for, say, a VPN software interface, e.g.

PPP adapter name withheld:

       Connection-specific DNS Suffix  . :
       Description . . . . . . . . . . . : WAN (PPP/SLIP) Interface
       Physical Address. . . . . . . . . : 00-53-45-00-00-00
       Dhcp Enabled. . . . . . . . . . . : No
       IP Address. . . . . . . . . . . . : withheld
       Subnet Mask . . . . . . . . . . . :
       Default Gateway . . . . . . . . . : withheld
       DNS Servers . . . . . . . . . . . : withheld
       Primary WINS Server . . . . . . . : withheld
       Secondary WINS Server . . . . . . : withheld

--Dinosaurclover (talk) 21:07, 23 November 2008 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.