MAC address: Wikis

  

Encyclopedia

From Wikipedia, the free encyclopedia

.In computer networking, a Media Access Control address (MAC address) is a unique identifier assigned to most network adapters or network interface cards (NICs) by the manufacturer for identification, and used in the Media Access Control protocol sub-layer.^ These addresses are assigned when the cards are manufactured.
  • Ask Ein: Finding the MAC address of your Clié TH-55 23 January 2010 5:18 UTC askein.eingang.org [Source type: General]

^ The MAC Address is the Media Access Control, which is a unique value assigned to computer hardware for identification purposes.
  • What is a MAC Address? 23 January 2010 5:18 UTC blog.neds.com [Source type: General]

^ MAC address assignment of ftServer V Series and Continuum network interface adapters .
  • MAC address assignment of ftServer� V Series and Continuum� network interface adapters, Noah Davids 23 January 2010 5:18 UTC members.cox.net [Source type: Reference]

.If assigned by the manufacturer, a MAC address usually encodes the manufacturer's registered identification number.^ These addresses are assigned when the cards are manufactured.
  • Ask Ein: Finding the MAC address of your Clié TH-55 23 January 2010 5:18 UTC askein.eingang.org [Source type: General]

^ A MAC address is a 12-digit number.

^ The second half of a MAC address represents the serial number assigned to the adapter by the manufacturer.
  • Find MAC AddressTool with changing MAC Address Function 23 January 2010 5:18 UTC amac.paqtool.com [Source type: General]

.It may also be known as an Ethernet Hardware Address (EHA), hardware address, adapter address, or physical address.^ It may also be called the ethernet address, ethernet hardware address, or physical address.
  • WolfTech - Finding your MAC address 23 January 2010 5:18 UTC www.wolftech.ncsu.edu [Source type: General]

^ A MAC address is also known as physical addresser hardware address.

^ The MAC address is also known as the "physical address."
  • How to Find the MAC Address of Your Computer | eHow.com 23 January 2010 5:18 UTC www.ehow.com [Source type: General]

.There are three numbering spaces, managed by the Institute of Electrical and Electronics Engineers (IEEE), which are in common use for formulating a MAC address: MAC-48, EUI-48, and EUI-64. The IEEE claims trademarks on the names "EUI-48" and "EUI-64", where "EUI" stands for Extended Unique Identifier.^ The MAC address first three octets are known as the Organizationally Unique Identifier .
  • Ethernet MAC address - ArmadeusWiki 23 January 2010 5:18 UTC www.armadeus.com [Source type: FILTERED WITH BAYES]

^ Find mac address using vista?
  • WikiAnswers - How do you find out your Mac address for vista 23 January 2010 5:18 UTC wiki.answers.com [Source type: General]

^ EUI is an abbreviation of Extended Unique Identifier.

.Although intended to be a permanent and globally unique identification, it is possible to change the MAC address on most of today's hardware, an action often referred to as MAC spoofing.^ Change a MAC Address through Cloning .

^ Visit homepage of a-Mac Address Change .
  • a-Mac Address Change free download. Change your Mac Address in seconds! Scan Mac Address within any range of IP address. Exports the scanning results from a Mac Address Lookup list. Chan... 23 January 2010 5:18 UTC www.freedownloadscenter.com [Source type: General]

^ Although MAC addresses are typically static, they can be changed, or "spoofed".
  • What is a Mac address? Is it just for Mac computers? - The Sage Colleges 23 January 2010 5:18 UTC kb.sage.edu [Source type: General]

.Unlike IP address spoofing, where a sender spoofing their address in a request tricks the other party into sending the response elsewhere, in MAC address spoofing, the response is received by the spoofing party.^ About the Sending MAC Address function .
  • SOLLAE SYSTEMS ENGLISH BLOG :: About the Sending MAC Address function 23 January 2010 5:18 UTC blog.eztcp.com [Source type: General]

^ One is MAC address from the receiving machine and other one from the receiving machine.
  • Find MAC Address: My MAC Address Lookup | Get MAC Address Finder 23 January 2010 5:18 UTC www.ipaddresslocation.org [Source type: General]

^ Bind MAC/IP spoofed ip 5.1 spoofed ip in seconds!
  • Find Mac Address 5.1 review and download. 23 January 2010 5:18 UTC rbytes.net [Source type: General]
  • Find Mac Address pro 5.1 review and download. 23 January 2010 5:18 UTC rbytes.net [Source type: General]

.However, MAC address spoofing is limited to the local broadcast domain.^ Want to spoof a MAC Address?
  • Find MAC AddressTool with changing MAC Address Function 23 January 2010 5:18 UTC amac.paqtool.com [Source type: General]

^ Spoofing the MAC address - Bruce Raisley .
  • Spoofing the MAC address - Bruce Raisley 23 January 2010 5:18 UTC bruceraisley.com [Source type: General]
  • Spoofing the MAC address - Bruce Raisley 23 January 2010 5:18 UTC blog.bruceraisley.com [Source type: General]

^ Also, remember that MAC addresses can be spoofed.
  • How do I look up a MAC address? Security - dslreports.com 23 January 2010 5:18 UTC www.dslreports.com [Source type: General]

.A host cannot determine from the MAC address of another host whether that host is on the same OSI Layer 2 network segment as the sending host, or on a network segment bridged to that network segment.^ A host cannot determine from the MAC address of another host whether that host is on the same OSI Layer 2 network segment as the sending host, or on a network segment bridged to that network segment.
  • DIDX Knowledge Base : What is Mac Address 23 January 2010 5:18 UTC kb.didx.net [Source type: Reference]

^ Determine IP address of network printer .
  • Determine IP address of network printer - Mac Forums 23 January 2010 5:18 UTC forums.macrumors.com [Source type: General]

^ The MAC address stays the same as before .
  • How to change MAC-Address in Windows Registry | Windows Reference 23 January 2010 5:18 UTC www.windowsreference.com [Source type: General]

.In TCP/IP networks, the MAC address of a subnet interface can be queried with the IP address using the Address Resolution Protocol (ARP) for Internet Protocol Version 4 (IPv4) or the Neighbor Discovery Protocol (NDP) for IPv6.^ Determine your external IP Address for use out on the internet.
  • Manually Configurare a Static IP Address 23 January 2010 5:18 UTC homepage.mac.com [Source type: General]

^ When we query MAC address on IPV6 we are getting EUI-48 address fprmat.
  • NIC with EUI-64 MAC address format. 23 January 2010 5:18 UTC communities.intel.com [Source type: General]

^ A network address is the logical protocol address assigned to the network to which the interface is connected.
  • InformIT: Networking Components and Devices > Identifying MAC Addresses 23 January 2010 5:18 UTC www.informit.com [Source type: General]

.On broadcast networks, such as Ethernet, the MAC address uniquely identifies each node on that segment and allows frames to be marked for specific hosts.^ The MAC address will be shown as Ethernet ID .
  • mac_address - DVInfo 23 January 2010 5:18 UTC dvinfo.ifh.de [Source type: FILTERED WITH BAYES]

^ A "MAC address" is a unique identifier for an Ethernet or wireless port that is assigned by the manufacturer.
  • MAC Address Authentication 23 January 2010 5:18 UTC hotspotpa.com [Source type: General]

^ Every adapter has a unique MAC address.
  • What is the IPv4 MAC address (aka the hardware or physicaladdress) of my network adapter? - Knowledge Base 23 January 2010 5:18 UTC kb.iu.edu [Source type: Reference]

.It thus forms the basis of most of the Link layer (OSI Layer 2) networking upon which upper layer protocols rely to produce complex, functioning networks.^ Layer 2 of the OSI model is the Data Link Layer .
  • MAC Address 23 January 2010 5:18 UTC www.topbits.com [Source type: General]

^ Therefore, it forms the basis for layer 2 networking in which higher layer protocols are built.
  • Learn about the MAC address and network devices 23 January 2010 5:18 UTC glossary.spamlaws.com [Source type: Academic]

^ MAC addresses are used for local delivery of MAC (Media Access Control)-layer packets (e.g., ethernet frames) but not in global network protocols.
  • Micronet Mail Archive: Re: MAC address in SNS report? 23 January 2010 5:18 UTC ls.berkeley.edu [Source type: FILTERED WITH BAYES]

Contents

Notational conventions

.The standard (IEEE 802) format for printing MAC-48 addresses in human-friendly form is six groups of two hexadecimal digits, separated by hyphens (-) or colons (:), in transmission order, e.g.^ Addresses are formatted as six groups of two hexadecimal digits, such as the following, .
  • What is a Mac address? Is it just for Mac computers? - The Sage Colleges 23 January 2010 5:18 UTC kb.sage.edu [Source type: General]

^ It returns MAC address in string format.
  • Convert MAC Address String into Bytes - CodeProject 23 January 2010 5:18 UTC www.codeproject.com [Source type: Academic]

^ For this reason, MAC addresses are made up of six two-digit hexadecimal numbers, separated by colons.
  • What is a Mac address? Is it just for Mac computers? - The Sage Colleges 23 January 2010 5:18 UTC kb.sage.edu [Source type: General]

.01-23-45-67-89-ab, 01:23:45:67:89:ab.^ AB eth1 Current MAC: 00:40:96:43:87:65 [wireless] (Cisco/Aironet 4800/340) Faked MAC: 01:23:45:67:89:ab (unknown) .
  • Change Your MAC Address | Windows 7 Help is around the corner – GoITExpert.com 23 January 2010 5:18 UTC www.goitexpert.com [Source type: General]

^ For example, in the MAC address 00-14-22-01-23-45, the first three octets are 00-14-22.
  • What Is My IP Address? - What is a MAC address? 23 January 2010 5:18 UTC whatismyipaddress.com [Source type: FILTERED WITH BAYES]

^ Only this format returns a device: 01:23:45:67:89:ab.  Is that something you would like to be able to do?  IE be able to search via all 3 formats?   .
  • FindIT MAC address format - Netcordia Community 23 January 2010 5:18 UTC connection.netcordia.com [Source type: FILTERED WITH BAYES]

.This form is also commonly used for EUI-64. Another convention commonly used by Cisco and Cisco-like networking equipment uses three groups of four hexadecimal digits separated by dots (.), e.g.^ A MAC (Media Access Control) address is a 12-digit string of hexadecimal characters used to uniquely identify your network adapter.
  • K-STATE AT SALINA - How to find my MAC address 23 January 2010 5:18 UTC www.sal.ksu.edu [Source type: General]

^ A MAC address takes the form of six pairs of hexadecimal digits, usually separated by colons or dashes, and will look something like this—01:1F:33:69:BC:14.
  • A Networking Primer: What’s a MAC Address? - www.smallbusinesscomputing.com 23 January 2010 5:18 UTC www.smallbusinesscomputing.com [Source type: General]

^ IEEE expects MAC-48 space to be exhausted around the year 2100 at which time a newer specification such as EUI-64 will have to be used.

0123.4567.89ab; again in transmission order.

Address details

MAC-48 Address.svg
.The original IEEE 802 MAC address comes from the original Xerox Ethernet addressing scheme.^ Procedure to get the original MAC address from ROM .
  • How-To Change Your MAC Address 23 January 2010 5:18 UTC forgeftp.novell.com [Source type: General]

^ The MAC address is also sometimes called the ethernet address.
  • Information Management Systems & Services 23 January 2010 5:18 UTC www.imss.caltech.edu [Source type: General]

^ Numbering scheme for MAC address bits.
  • MAC Address I/G G/L bits - Lammle Forum 23 January 2010 5:18 UTC www.lammle.com [Source type: General]

[1] .This 48-bit address space contains potentially 248 or 281,474,976,710,656 possible MAC addresses.^ A MAC address is 48 bits long.
  • MAC Address 23 January 2010 5:18 UTC www.topbits.com [Source type: General]
  • All about MAC Address 23 January 2010 5:18 UTC www.brighthub.com [Source type: General]

^ The 48 stands for 48-bits, meaning that this space contains potentially 2^48 or 281,474,976,710,656 possible addresses.

^ Numbering scheme for MAC address bits.
  • MAC Address I/G G/L bits - Lammle Forum 23 January 2010 5:18 UTC www.lammle.com [Source type: General]

.All three numbering systems use the same format and differ only in the length of the identifier.^ The "model " property is useful to identify the specific piece of hardware (the plug-in card), as opposed to the " name " property (since several different but functionally-equivalent cards would have the same " name " property, thus calling the same device driver).
  • "local-mac-address" (Writing FCode Programs) - Sun Microsystems 23 January 2010 5:18 UTC docs.sun.com [Source type: Reference]

^ The first three numbers, 00:1C:B3, are an Apple manufacturing code; only Apple products will have MAC address starting with those digits.
  • MAC Address for Unix 23 January 2010 5:18 UTC www.uic.edu [Source type: General]
  • MAC Address for Windows and Macs 23 January 2010 5:18 UTC www.uic.edu [Source type: General]

^ M edia A ccess C ontrol address) The unique serial number burned into Ethernet and Token Ring adapters that identifies that network card from all others.
  • Wireless Net DesignLine : Design Resource for Automotive Engineering 23 January 2010 5:18 UTC www.wirelessnetdesignline.com [Source type: General]
  • MAC Address: Definition and additional resources from ZDNet 23 January 2010 5:18 UTC dictionary.zdnet.com [Source type: General]

.Addresses can either be "universally administered addresses" or "locally administered addresses."^ If the bit is 0, the address is universally administered.
  • MAC Address I/G G/L bits - Lammle Forum 23 January 2010 5:18 UTC www.lammle.com [Source type: General]

^ Locally Administered Addresses first digits.
  • How to change MAC-Address in Windows Registry | Windows Reference 23 January 2010 5:18 UTC www.windowsreference.com [Source type: General]

^ If it is 1, the address is locally administered.
  • MAC Address I/G G/L bits - Lammle Forum 23 January 2010 5:18 UTC www.lammle.com [Source type: General]

.A universally administered address is uniquely assigned to a device by its manufacturer; these are sometimes called "burned-in addresses" (BIA).^ These addresses are assigned when the cards are manufactured.
  • Ask Ein: Finding the MAC address of your Clié TH-55 23 January 2010 5:18 UTC askein.eingang.org [Source type: General]

^ If the bit is 0, the address is universally administered.
  • MAC Address I/G G/L bits - Lammle Forum 23 January 2010 5:18 UTC www.lammle.com [Source type: General]

^ The rest of three bytes are assigned by the device manufacturer and these are always unique.
  • All about MAC Address 23 January 2010 5:18 UTC www.brighthub.com [Source type: General]

.The first three octets (in transmission order) identify the organization that issued the identifier and are known as the Organizationally Unique Identifier (OUI).^ The MAC address first three octets are known as the Organizationally Unique Identifier .
  • Ethernet MAC address - ArmadeusWiki 23 January 2010 5:18 UTC www.armadeus.com [Source type: FILTERED WITH BAYES]

^ The first 24 bits correspond to the Organizationally Unique Identifier.
  • Three ways to get your MAC address. — CodeGuru.com 23 January 2010 5:18 UTC www.codeguru.com [Source type: General]

^ In computer networking, a Media Access Control address, better known as MAC address, is a unique identifier assigned to a network adapter or network interface card (NIC) by the manufacturer for identification.
  • MAC Address for Unix 23 January 2010 5:18 UTC www.uic.edu [Source type: General]
  • MAC Address for Windows and Macs 23 January 2010 5:18 UTC www.uic.edu [Source type: General]

[2] .The following three (MAC-48 and EUI-48) or five (EUI-64) octets are assigned by that organization in nearly any manner they please, subject to the constraint of uniqueness.^ The MAC address first three octets are known as the Organizationally Unique Identifier .
  • Ethernet MAC address - ArmadeusWiki 23 January 2010 5:18 UTC www.armadeus.com [Source type: FILTERED WITH BAYES]

^ If you are still unable to find your MAC-Address after using the following instructions, please refer to your product manual or contact the manufacturer of your device.
  • Game Console MAC Address Instructions 23 January 2010 5:18 UTC www.deltastate.edu [Source type: General]

^ Represented by twelve hexadecimal bytes , the first six of which comprise the Organizational Unique Identifier and are assigned by the IEEE , the last six of which represent the interface serial number.
  • MAC address@Everything2.com 23 January 2010 5:18 UTC www.everything2.com [Source type: General]
  • MAC address@Everything2.com 23 January 2010 5:18 UTC everything2.com [Source type: General]

.The IEEE expects the MAC-48 space to be exhausted no sooner than the year 2100[3]; EUI-64s are not expected to run out in the foreseeable future.^ We've got two routers on a segment running HSRP, so first we need to find out what the MAC address of the HSRP virtual router is.
  • BCMSN Tutorial: The HSRP MAC Address 23 January 2010 5:18 UTC www.mcmcse.com [Source type: General]
  • Cisco CCNP Hot Standby Routing Protocol HSRP MAC Address 23 January 2010 5:18 UTC www.thebryantadvantage.com [Source type: FILTERED WITH BAYES]

^ The software will run automatically and hide your IP address with no setup required other than...
  • Download Hide Mac Address - Hide IP NG, Mask My IP Anonymity - Hide IP Address, SmartHide, Hide IP 23 January 2010 5:18 UTC finaldownload.com [Source type: FILTERED WITH BAYES]

^ Out with the Old; In with the New By John Traenkenschuh on January 3, 2010 No Comments Time to think through last year's work and this year's goals .
  • InformIT: Networking Components and Devices > Identifying MAC Addresses 23 January 2010 5:18 UTC www.informit.com [Source type: General]

.A locally administered address is assigned to a device by a network administrator, overriding the burned-in address.^ Locally-administered addresses Don in Chicagoland .

^ An IP address is assigned to every device on a network so that device can be located on the network.
  • What's the difference between a Mac Address and an IP Address? 23 January 2010 5:18 UTC ask-leo.com [Source type: General]

^ Locally Administered Addresses first digits.
  • How to change MAC-Address in Windows Registry | Windows Reference 23 January 2010 5:18 UTC www.windowsreference.com [Source type: General]

.Locally administered addresses do not contain OUIs.^ Locally Administered Addresses first digits.
  • How to change MAC-Address in Windows Registry | Windows Reference 23 January 2010 5:18 UTC www.windowsreference.com [Source type: General]

^ Locally administered addresses do not contain OUIs.
  • MAC Address I/G G/L bits - Lammle Forum 23 January 2010 5:18 UTC www.lammle.com [Source type: General]

^ Locally-administered addresses Don in Chicagoland .

.Universally administered and locally administered addresses are distinguished by setting the second least significant bit of the most significant byte of the address.^ If the bit is 0, the address is universally administered.
  • MAC Address I/G G/L bits - Lammle Forum 23 January 2010 5:18 UTC www.lammle.com [Source type: General]

^ Locally-administered addresses Don in Chicagoland .

^ Locally Administered Addresses first digits.
  • How to change MAC-Address in Windows Registry | Windows Reference 23 January 2010 5:18 UTC www.windowsreference.com [Source type: General]

.If the bit is 0, the address is universally administered.^ If the bit is 0, the address is universally administered.
  • MAC Address I/G G/L bits - Lammle Forum 23 January 2010 5:18 UTC www.lammle.com [Source type: General]

^ Universally administered and locally administered addresses are distinguished by setting the second least significant bit of the most significant byte of the address.
  • MAC Address I/G G/L bits - Lammle Forum 23 January 2010 5:18 UTC www.lammle.com [Source type: General]

^ If the second-lowest bit of the first octet is set, the address is "locally administered" and not assumed to be worldwide-unique.
  • 10.3: Change Ethernet MAC address from the Terminal - Mac OS X Hints 23 January 2010 5:18 UTC www.macosxhints.com [Source type: FILTERED WITH BAYES]

.If it is 1, the address is locally administered.^ Locally Administered Addresses first digits.
  • How to change MAC-Address in Windows Registry | Windows Reference 23 January 2010 5:18 UTC www.windowsreference.com [Source type: General]

^ If it is 1, the address is locally administered.
  • MAC Address I/G G/L bits - Lammle Forum 23 January 2010 5:18 UTC www.lammle.com [Source type: General]

^ Therefore, it is a locally administered address.
  • MAC Address I/G G/L bits - Lammle Forum 23 January 2010 5:18 UTC www.lammle.com [Source type: General]

.In the example address 02-00-00-00-00-01 the most significant byte is 02 (hex).^ The most significant byte is 02h.
  • MAC Address I/G G/L bits - Lammle Forum 23 January 2010 5:18 UTC www.lammle.com [Source type: General]

^ The Wi-Fi Mac address on my iPhone, for example is: 00:1C:B3:09:85:15.
  • MAC Address for Windows and Macs 23 January 2010 5:18 UTC www.uic.edu [Source type: General]

^ To set the range of 256 addresses, the last octet of the MinimumMacAddress is set to 00 and the last octet of the MaximumMacAddress is set to FF. This sets the MAC address pool range from 00-15-5d-01-85-00 to 00-15-5d-01-85-FF. .
  • Dealing with MAC address pool duplication in Hyper-V 23 January 2010 5:18 UTC www.virtualizationadmin.com [Source type: FILTERED WITH BAYES]

.The binary is 00000010 and the second least significant bit is 1. Therefore, it is a locally administered address.^ If the bit is 0, the address is universally administered.
  • MAC Address I/G G/L bits - Lammle Forum 23 January 2010 5:18 UTC www.lammle.com [Source type: General]

^ Locally-administered addresses Don in Chicagoland .

^ The binary is 000000 1 0 and the second least significant bit is 1.
  • MAC Address I/G G/L bits - Lammle Forum 23 January 2010 5:18 UTC www.lammle.com [Source type: General]

[4] .The bit is 0 in all OUIs.^ The bit is 0 in all OUIs.
  • MAC Address I/G G/L bits - Lammle Forum 23 January 2010 5:18 UTC www.lammle.com [Source type: General]

.If the least significant bit of the most significant byte is set to a 0, the packet is meant to reach only one receiving NIC.^ This will set the snaplength (normaly the number of bytes per packet to capture) to 0, which tcpdump interprets as "capture the whole thing".
  • MAC Address and ARP Spoofing v1.3 by stevecronin - Antionline Forums - Maximum Security for a Connected World 23 January 2010 5:18 UTC www.antionline.com [Source type: General]

^ NetChanger is your best friend who can help you to change your ip address and othe network settings with only one click!

^ The only active Finder window displayed is the front-most one and displays only what is in my PowerBook hard drive in the present.
  • 10.5: Repair Time Machine after logic board changes - Mac OS X Hints 23 January 2010 5:18 UTC www.macosxhints.com [Source type: FILTERED WITH BAYES]

This is called unicast. .If the least significant bit of the most significant byte is set to a 1, the packet is meant to be sent only once but still reach several NICs.^ This will set the snaplength (normaly the number of bytes per packet to capture) to 0, which tcpdump interprets as "capture the whole thing".
  • MAC Address and ARP Spoofing v1.3 by stevecronin - Antionline Forums - Maximum Security for a Connected World 23 January 2010 5:18 UTC www.antionline.com [Source type: General]

^ Windows has a registry key that, if set, replaces the MAC address for every outgoing packet sent.
  • How can I change my media access control (MAC) address under Windows NT 4.0? 23 January 2010 5:18 UTC windowsitpro.com [Source type: General]

^ Also, tcpdump will by default only capture the first 96 bytes of packets it sees, which is enough for TCP header information.
  • MAC Address and ARP Spoofing v1.3 by stevecronin - Antionline Forums - Maximum Security for a Connected World 23 January 2010 5:18 UTC www.antionline.com [Source type: General]

This is called multicast.
The following technologies use the MAC-48 identifier format:
.
  • Ethernet
  • 802.11 wireless networks
  • Bluetooth
  • IEEE 802.5 token ring
  • most other IEEE 802 networks
  • FDDI
  • ATM (switched virtual connections only, as part of an NSAP address)
  • Fibre Channel and Serial Attached SCSI (as part of a World Wide Name)
  • The ITU-T G.hn standard, which provides a way to create a high-speed (up to 1 Gigabit/s) Local area network using existing home wiring (power lines, phone lines and coaxial cables).^ Ethernet adapter Local Area Connection 2: .
    • What's the difference between a Mac Address and an IP Address? 23 January 2010 5:18 UTC ask-leo.com [Source type: General]

    ^ Ethernet Standards IEEE 802.3 is the signaling standards for Ethernet, and IEEE 802.11 is the standards for Wi-Fi.
    • What is MAC Address? 23 January 2010 5:18 UTC www.iplocation.net [Source type: Reference]

    ^ On most apple laptops en0 is ethernet and en1 is wireless network.
    • Changing Your MAC Address (Wireless) | Mac Tricks And Tips 23 January 2010 5:18 UTC www.mactricksandtips.com [Source type: General]

    The G.hn Application Protocol Convergence (APC) layer accepts Ethernet frames that use the MAC-48 format and encapsulates them into G.hn MAC Service Data Units (MSDUs).
.The distinction between EUI-48 and MAC-48 identifiers is purely semantic: MAC-48 is used for network hardware; EUI-48 is used to identify other devices and software.^ Other hardware and software may be assigned their own MAC addresses.
  • [VBnet Network]  Netbios: Determine Local Adapter MAC Address 23 January 2010 5:18 UTC vbnet.mvps.org [Source type: Reference]

^ The MAC address is used by the network to identify which piece of hardware a packet of information is to be sent to.
  • Can a MAC address be traced? 23 January 2010 5:18 UTC ask-leo.com [Source type: General]

^ MAC Address Media Access Control address The unique serial number burned into Ethernet and Token Ring adapters that identifies that network card from all others.
  • mac address Resources | ZDNet 23 January 2010 5:18 UTC updates.zdnet.com [Source type: General]

.(Thus, by definition, an EUI-48 is not in fact a "MAC address", although it is syntactically indistinguishable from one and assigned from the same numbering space.^ A MAC address is 48 bits long.
  • All about MAC Address 23 January 2010 5:18 UTC www.brighthub.com [Source type: General]

^ The MAC address stays the same as before .
  • How to change MAC-Address in Windows Registry | Windows Reference 23 January 2010 5:18 UTC www.windowsreference.com [Source type: General]

^ MAC addresses are presented as 48 bit hex numbers, which are assigned by the manufacturer of the card.
  • MAC Address and ARP Spoofing v1.3 by stevecronin - Antionline Forums - Maximum Security for a Connected World 23 January 2010 5:18 UTC www.antionline.com [Source type: General]

)
.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.^ A MAC address is 48 bits long.
  • All about MAC Address 23 January 2010 5:18 UTC www.brighthub.com [Source type: General]

^ Set specific MAC address of a network interface .
  • Change your Network Card MAC Address on Ubuntu | Ubuntu Geek 23 January 2010 5:18 UTC www.ubuntugeek.com [Source type: General]

^ Identify the computer type and mac address .
  • MAC Address Changer for Windows XP/2003 - CodeProject 23 January 2010 5:18 UTC www.codeproject.com [Source type: General]

.Instead, the term EUI-48 should be used for this purpose.^ Since I am using the same startup Volume on both computers, that should keep Time machine current enough for my purposes.
  • 10.5: Repair Time Machine after logic board changes - Mac OS X Hints 23 January 2010 5:18 UTC www.macosxhints.com [Source type: FILTERED WITH BAYES]

^ You should have used the term "kudos-seeking", not "kudo-seeking".RE: The easy way to avoid a Wi-Fi virusHow about MAC...
  • mac address Resources | ZDNet 23 January 2010 5:18 UTC updates.zdnet.com [Source type: General]

^ The impact To put it in the simplest of terms, approximately 50 percent of all traffic that should be delivered to the default gateway for routing will instead be delivered to the targeted computer.

EUI-64 identifiers are used in:
  • FireWire
  • IPv6 (as the least-significant 64 bits of a unicast network address or link-local address when stateless autoconfiguration is used)
  • ZigBee / 802.15.4 / 6LoWPAN wireless personal-area networks
The IEEE has built in several special address types to allow more than one network interface card to be addressed at one time:
.
  • Packets sent to the broadcast address, all one bits, are received by all stations on a local area network.^ MAC address (Media Access Control) One of the two addresses every networked computer has (the other being an IP address), a Media Access Control address is a unique 48-bit identifier usually written as 12 hexadecimal characters grouped in pairs (e.
    • M: Network Security Glossary | WatchGuard 23 January 2010 5:18 UTC www.watchguard.com [Source type: Reference]

    ^ Given that IP addresses can’t be permanently assigned to a device—after all, a particular address can belong to one computer today and another one tomorrow— MAC addresses allow communication between devices on a local network by making it possible to reliably distinguish one computer from another.
    • A Networking Primer: What’s a MAC Address? - www.smallbusinesscomputing.com 23 January 2010 5:18 UTC www.smallbusinesscomputing.com [Source type: General]

    ^ If no MAC address is specified to Windows(TM), it uses the hard coded one in the NIC to construct Ethernet or IEEE network frames (or simply packets), which are used at OSI layer 2.
    • Technitium MAC Address Changer v5 Release 3 (FREEWARE) 23 January 2010 5:18 UTC tmac.technitium.com [Source type: General]

    In hexadecimal the broadcast address would be "FF:FF:FF:FF:FF:FF".
  • Packets sent to a multicast address are received by all stations on a LAN that have been configured to receive packets sent to that address.
  • Functional addresses identify one or more Token Ring NICs that provide a particular service, defined in IEEE 802.5.
.These are "group addresses", as opposed to "individual addresses"; the least significant bit of the first octet of a MAC address distinguishes individual addresses from group addresses.^ There are six octets in a MAC address.
  • How do I find the MAC Address on my Wireless Access Point? 23 January 2010 5:18 UTC getsatisfaction.com [Source type: FILTERED WITH BAYES]

^ MAC address (Media Access Control) One of the two addresses every networked computer has (the other being an IP address), a Media Access Control address is a unique 48-bit identifier usually written as 12 hexadecimal characters grouped in pairs (e.
  • M: Network Security Glossary | WatchGuard 23 January 2010 5:18 UTC www.watchguard.com [Source type: Reference]

^ MAC addresses are 6-byte (48-bits) in length, and are written in MM:MM:MM:SS:SS:SS format.
  • What is MAC Address? 23 January 2010 5:18 UTC www.iplocation.net [Source type: Reference]

.That bit is set to 0 in individual addresses and 1 in group addresses.^ Fortunately Address Book lets you set a default email address to use for each contact in the group.
  • Mac Address Book tips: 5 more handy hints -- Reality Distortion: Macs, Mac OS X, and Apple stuff 23 January 2010 5:18 UTC mac.elated.com [Source type: General]

^ (You can also set each contact’s default physical address and phone number for the group – used when printing contacts.
  • Mac Address Book tips: 5 more handy hints -- Reality Distortion: Macs, Mac OS X, and Apple stuff 23 January 2010 5:18 UTC mac.elated.com [Source type: General]

^ Each individual device is given a unique MAC address in the form of 12 digits, each set of two divided by a colon.
  • MAC Address Lookup: Find MAC Address | Change MAC Address Finder 23 January 2010 5:18 UTC www.find-ip-address.org [Source type: General]

.Group addresses, like individual addresses, can be universally administered or locally administered.^ Locally Administered Addresses first digits.
  • How to change MAC-Address in Windows Registry | Windows Reference 23 January 2010 5:18 UTC www.windowsreference.com [Source type: General]

^ Standards allow for several IEEE formats, as well as 64-bit formats for IP and locally administered names.Like the 48-bit MAC address … 25 November 2003 Tags: Fabric • Node • Ieee • Frames • Tom • Attachment .
  • Logs mac address articles - Techworld.com 23 January 2010 5:18 UTC search.techworld.com [Source type: General]

^ Under "General" tab, click on the "Configure" button d) Click on "Advanced" tab e) Under "Property section", you should see an item called "Network Address" or "Locally Administered Address", click on it.
  • Changing Your MAC Address In Window XP/Vista, Linux And Mac OS X (Sometimes known as MAC spoofing) 23 January 2010 5:18 UTC www.irongeek.com [Source type: General]

.In addition, the EUI-64 numbering system encompasses both MAC-48 and EUI-48 identifiers by a simple translation mechanism.^ In addition, the VMware application does its best, but cannot guarantee, to automatically assign unique MAC addresses for virtual machines running on multiple host systems.
  • VMware KB: Changing the MAC Address of a Virtual Machine 23 January 2010 5:18 UTC kb.vmware.com [Source type: Reference]

^ However, you can change or spoof the MAC address in the operating system itself using a few simple tricks.

^ MAC addresses are presented as 48 bit hex numbers, which are assigned by the manufacturer of the card.
  • MAC Address and ARP Spoofing v1.3 by stevecronin - Antionline Forums - Maximum Security for a Connected World 23 January 2010 5:18 UTC www.antionline.com [Source type: General]

.To convert a MAC-48 into an EUI-64, copy the OUI, append the two octets "FF-FF", and then copy the organization-specified part.^ So if the IP address of the first enumerated NIC was 192.168.1.133, the last two octets are converted to hexadecimal 1.133 becomes 01-85 and used as the next two octets in the MAC address.  This gives 00-15-5d-01-85 as the first five octets.
  • Dealing with MAC address pool duplication in Hyper-V 23 January 2010 5:18 UTC www.virtualizationadmin.com [Source type: FILTERED WITH BAYES]

^ I've seen where I can go into the settings and manully define a MAC address via the GUI but it will not allow me to change the first 3 octets from the ESX default.
  • VMware Communities: Change MAC address of VM to whatever ... 23 January 2010 5:18 UTC communities.vmware.com [Source type: General]

^ You will notice that all 3Com cards, for example, will have the same OUI, the first 3 octets in a MAC address.
  • Three ways to get your MAC address. — CodeGuru.com 23 January 2010 5:18 UTC www.codeguru.com [Source type: General]

.To convert an EUI-48 into an EUI-64, the same process is used, but the sequence inserted is "FF-FE". In both cases, the process can be trivially reversed when necessary.^ I went back into Terminal and checked what the BackupMachineAddress attribute was for both folders, and they are the same (the correct, new MAC address).
  • 10.5: Repair Time Machine after logic board changes - Mac OS X Hints 23 January 2010 5:18 UTC www.macosxhints.com [Source type: FILTERED WITH BAYES]

^ The short answer is it’s the same solution for both, I strongly suggest you pay the $10 to Simple Machines and use (O2M) Outlook to Mac for the heavy lifting.
  • Microsoft Entourage vs Apple Mail, Address Book & iCal : Switching To Mac 23 January 2010 5:18 UTC www.switchingtomac.com [Source type: General]

^ Since I am using the same startup Volume on both computers, that should keep Time machine current enough for my purposes.
  • 10.5: Repair Time Machine after logic board changes - Mac OS X Hints 23 January 2010 5:18 UTC www.macosxhints.com [Source type: FILTERED WITH BAYES]

Organizations issuing EUI-64s are cautioned against issuing identifiers that could be confused with these forms. .The IEEE policy is to discourage new uses of 48-bit identifiers in favor of the EUI-64 system.^ Standards allow for several IEEE formats, as well as 64-bit formats for IP and locally administered names.Like the 48-bit MAC address … 25 November 2003 Tags: Fabric • Node • Ieee • Frames • Tom • Attachment .
  • Logs mac address articles - Techworld.com 23 January 2010 5:18 UTC search.techworld.com [Source type: General]

^ GUIDs are used commonly to identify COM components and other objects in the system.
  • Three Ways To Get Your System's Network MAC Address 23 January 2010 5:18 UTC edn.embarcadero.com [Source type: FILTERED WITH BAYES]

^ The 48-bit MAC address is a globally unique identifier.
  • Three ways to get your MAC address. — CodeGuru.com 23 January 2010 5:18 UTC www.codeguru.com [Source type: General]

.IPv6—one of the most prominent standards that uses EUI-64—treats MAC-48 as EUI-48 instead (as it is chosen from the same address pool).^ MAC address it's the same number of IMEI? .

^ Deciphering the 48-bit MAC address .
  • Three ways to get your MAC address. — CodeGuru.com 23 January 2010 5:18 UTC www.codeguru.com [Source type: General]

^ Will it be the same as the mac address I had when I used windows?
  • How to find out my mac address? - Ubuntu Forums 23 January 2010 5:18 UTC ubuntuforums.org [Source type: FILTERED WITH BAYES]

This results in extending MAC addresses (such as IEEE 802 MAC address) to EUI-64 using "FF-FE" rather than "FF-FF."

Individual address block

.An Individual Address Block comprises a 24-bit OUI managed by the IEEE Registration Authority, followed by 12 IEEE-provided bits (identifying the organization), and 12 bits for the owner to assign to individual devices.^ In fabric environments, the switch is responsible for assigning a 24-bit address to each device as it logs on.
  • Logs mac address articles - Techworld.com 23 January 2010 5:18 UTC search.techworld.com [Source type: General]

^ The second 24 bits is administered by the company or organization that the OUI has been assigned to.
  • Three ways to get your MAC address. — CodeGuru.com 23 January 2010 5:18 UTC www.codeguru.com [Source type: General]

^ The first three bytes are assigned to the manufacturer by the Institute of Electrical and Electronics Engineers (IEEE), and are called the organizationally unique identifier (OUI).
  • MAC address assignment of ftServer� V Series and Continuum� network interface adapters, Noah Davids 23 January 2010 5:18 UTC members.cox.net [Source type: Reference]

.An IAB is ideal for organizations requiring fewer than 4097 unique 48-bit numbers (EUI-48).^ MAC addresses are 12-digit hexadecimal numbers (48 bits in length).
  • Find MAC AddressTool with changing MAC Address Function 23 January 2010 5:18 UTC amac.paqtool.com [Source type: General]

^ MAC addresses are presented as 48 bit hex numbers, which are assigned by the manufacturer of the card.
  • MAC Address and ARP Spoofing v1.3 by stevecronin - Antionline Forums - Maximum Security for a Connected World 23 January 2010 5:18 UTC www.antionline.com [Source type: General]

^ The 48-bit MAC address is a globally unique identifier.
  • Three ways to get your MAC address. — CodeGuru.com 23 January 2010 5:18 UTC www.codeguru.com [Source type: General]

[5]

Bit-reversed notation

.The standard notation, also called canonical format, for MAC addresses is written in transmission bit order with the least significant bit transmitted first, as seen in the output of the iproute2/ifconfig/ipconfig command, for example.^ Restart machine, and check new MAC Address with ifconfig command.
  • Ubah MAC Address Network Card di Ubuntu:: the How-To Geek 23 January 2010 5:18 UTC www.howtogeek.com [Source type: General]
  • Palitan ang iyong Network Card MAC Address sa Ubuntu:: ang mga How-To Geek 23 January 2010 5:18 UTC www.howtogeek.com [Source type: General]

^ Part of the output of “ipconfig” command follows: .
  • HOWTO: Instantly change your MAC address - All Things Marked 23 January 2010 5:18 UTC allthingsmarked.com [Source type: General]

^ MAC address in hex notation.
  • 10.3: Change Ethernet MAC address from the Terminal - Mac OS X Hints 23 January 2010 5:18 UTC www.macosxhints.com [Source type: FILTERED WITH BAYES]

.However, since IEEE 802.3 (Ethernet) and IEEE 802.4 (Token Bus) send the bytes (octets) over the wire, left-to-right, with least significant bit in each byte first, while IEEE 802.5 (Token Ring) and IEEE 802.6 send the bytes over the wire with the most significant bit first, confusion may arise when an address in the latter scenario is represented with bits reversed from the canonical representation.^ MAC Address Media Access Control address The unique serial number burned into Ethernet and Token Ring adapters that identifies that network card from all others.
  • mac address Resources | ZDNet 23 January 2010 5:18 UTC updates.zdnet.com [Source type: General]

^ The first three bytes are assigned to the manufacturer by the Institute of Electrical and Electronics Engineers (IEEE), and are called the organizationally unique identifier (OUI).
  • MAC address assignment of ftServer� V Series and Continuum� network interface adapters, Noah Davids 23 January 2010 5:18 UTC members.cox.net [Source type: Reference]

^ M edia A ccess C ontrol address) The unique serial number burned into Ethernet and Token Ring adapters that identifies that network card from all others.
  • MAC Address: Definition and additional resources from ZDNet 23 January 2010 5:18 UTC dictionary.zdnet.com [Source type: General]

.For example, an address in canonical form 12-34-56-78-9A-BC would be transmitted over the wire as bits 01001000 00101100 01101010 00011110 01011001 00111101 in the standard transmission order (least significant bit first).^ I wrote two overloaded functions to get the MAC address: one returns the address formatted as a standard MAC address in HEX, punctuated with hyphens, e.g., "00-12-34-AB-CD-EF".
  • Getting the Physical (MAC) address of a Network Interface Card and finding out if it is the primary adapter on a multi-homed system - CodeProject 23 January 2010 5:18 UTC www.codeproject.com [Source type: FILTERED WITH BAYES]

^ MAC addresses are 12-digit hexadecimal numbers (48 bits in length).
  • Find MAC AddressTool with changing MAC Address Function 23 January 2010 5:18 UTC amac.paqtool.com [Source type: General]

^ The MAC address is the 12-digit number under the heading Wired MAC Address at the bottom of the screen.
  • Finding a MAC Hardware Address | LTS | Brandeis University 23 January 2010 5:18 UTC lts.brandeis.edu [Source type: General]

.But for Token Ring networks, it would be transmitted as bits 00010010 00110100 01010110 01111000 10011010 10111100 in most significant bit first order.^ M edia A ccess C ontrol address) The unique serial number burned into Ethernet and Token Ring adapters that identifies that network card from all others.
  • MAC Address: Definition and additional resources from ZDNet 23 January 2010 5:18 UTC dictionary.zdnet.com [Source type: General]

^ In that case the leftmost one is the broadcast bit and the next one in the LAA. This is a remnant of token-ring vs ethernet wars of a few decades ago.
  • How to change MAC-Address in Windows Registry | Windows Reference 23 January 2010 5:18 UTC www.windowsreference.com [Source type: General]

^ Universally administered and locally administered addresses are distinguished by setting the second least significant bit of the most significant byte of the address.
  • MAC Address I/G G/L bits - Lammle Forum 23 January 2010 5:18 UTC www.lammle.com [Source type: General]

The latter might be incorrectly displayed as 48-2C-6A-1E-59-3D. .This is referred to as bit-reversed order, non-canonical form, MSB format, IBM format, or Token Ring format as explained in RFC 2469.^ IBM token ring, PPP...
  • Three ways to get your MAC address. — CodeGuru.com 23 January 2010 5:18 UTC www.codeguru.com [Source type: General]

Canonical form is in general preferred, used by all modern implementations.
.When the first switches which supported both Token Ring and Ethernet came out, many switch vendors didn't understand this canonical form vs non-canonical form difference.^ M edia A ccess C ontrol address) The unique serial number burned into Ethernet and Token Ring adapters that identifies that network card from all others.
  • MAC Address: Definition and additional resources from ZDNet 23 January 2010 5:18 UTC dictionary.zdnet.com [Source type: General]

^ MAC addresses are an Ethernet (not PPP) thang Token-Ring and FDDI devices also have MAC addresses but, IIRC, you get into (big|little)-endian stuff there.
  • How can I find a MAC address from aremote IP ? 23 January 2010 5:18 UTC www.perlmonks.org [Source type: FILTERED WITH BAYES]

^ There many different switches that can be used to define various parameters of the program.
  • MAC Address and ARP Spoofing v1.3 by stevecronin - Antionline Forums - Maximum Security for a Connected World 23 January 2010 5:18 UTC www.antionline.com [Source type: General]

.As such, when the first few vendor's switches supporting both Token Ring and Ethernet in the same switch came out, there were numerous reports all over the world of Duplicate MAC Addresses, but it was actually the switch vendor's bugs which were not properly reversing the MAC addresses and thus causing the Duplicate MAC Address problem.^ The MAC address stays the same as before .
  • How to change MAC-Address in Windows Registry | Windows Reference 23 January 2010 5:18 UTC www.windowsreference.com [Source type: General]

^ There are six octets in a MAC address.
  • How do I find the MAC Address on my Wireless Access Point? 23 January 2010 5:18 UTC getsatisfaction.com [Source type: FILTERED WITH BAYES]

^ Each ethernet card in the world has a unique MAC address.
  • Three ways to get your MAC address. — CodeGuru.com 23 January 2010 5:18 UTC www.codeguru.com [Source type: General]

See also

  • NSAP address, another endpoint addressing scheme.
  • Cisco .Hot Standby Router Protocol or standard alternative VRRP Virtual Router Redundancy Protocol, which allows multiple routers to share one IP address and MAC address to provide router redundancy.^ We have it set to a allow list of MAC addresses.
    • Microsoft Windows DHCP Team Blog : DHCP Server Callout DLL for MAC Address based filtering - MAC Address List File Format 23 January 2010 5:18 UTC blogs.technet.com [Source type: General]

    ^ The MAC for the laptops are in the allow list but the DHCP will not assign an ip address.
    • Microsoft Windows DHCP Team Blog : DHCP Server Callout DLL for MAC Address based filtering - MAC Address List File Format 23 January 2010 5:18 UTC blogs.technet.com [Source type: General]

    ^ What is the difference between a Mac Address and an IP Address?
    • What's the difference between a Mac Address and an IP Address? 23 January 2010 5:18 UTC ask-leo.com [Source type: General]

    The OpenBSD project has an open source alternative, the Common Address Redundancy Protocol (CARP).
  • Internet Protocol version 6

References

  1. ^ IEEE Std 802-2001
  2. ^ IEEE OUI and Company_id Assignments
  3. ^ Guidelines for use of the 24-bit Organizationally Unique Identifiers
  4. ^ Standard Group MAC Addresses: A Tutorial Guide
  5. ^ "What is an Individual Address Block?". http://standards.ieee.org/faqs/OUI.html#q2. Retrieved 2006-07-09. 

External links


A Media Access Control address (MAC address) is a unique identifier assigned to network interfaces for communications on the physical network segment. Logically, MAC addresses are used in the Media Access Control protocol sub-layer of the OSI reference model.

MAC addresses are most often assigned by the manufacturer of a network interface card (NIC) and are stored in its hardware, the card's read-only memory, or some other firmware mechanism. If assigned by the manufacturer, a MAC address usually encodes the manufacturer's registered identification number. It may also be known as an Ethernet hardware address (EHA), hardware address, adapter address, or physical address.

MAC addresses are formed according to the rules of one of three numbering name spaces managed by the Institute of Electrical and Electronics Engineers (IEEE): MAC-48, EUI-48, and EUI-64. The IEEE claims trademarks on the names EUI-48 and EUI-64, in which EUI is an acronym for Extended Unique Identifier.

Although intended to be a permanent and globally unique identification, it is possible to change the MAC address on most of today's hardware, an action often referred to as MAC spoofing. Unlike IP address spoofing, where senders spoofing their address in a request direct the receiver into sending the response elsewhere, in MAC address spoofing, the response is received by the spoofing party. However, MAC address spoofing is limited to the local broadcast domain.

A host cannot determine from the MAC address of another host whether that host is on the same link (network segment) as the sending host, or on a network segment bridged to that network segment.

In TCP/IP networks, the MAC address of an interface can be queried knowing the IP address using the Address Resolution Protocol (ARP) for Internet Protocol Version 4 (IPv4) or the Neighbor Discovery Protocol (NDP) for IPv6. On broadcast networks, such as Ethernet, the MAC address uniquely identifies each node on that segment and allows frames to be marked for specific hosts. It thus forms the basis of most of the Link layer (OSI Layer 2) networking upon which upper layer protocols rely to produce complex, functioning networks.

Contents

Notational conventions

The standard (IEEE 802) format for printing MAC-48 addresses in human-friendly form is six groups of two hexadecimal digits, separated by hyphens (-) or colons (:), in transmission order, e.g. 01-23-45-67-89-ab, 01:23:45:67:89:ab. This form is also commonly used for EUI-64. Another convention commonly used by networking equipment uses three groups of four hexadecimal digits separated by dots (.), e.g. 0123.4567.89ab; again in transmission order.

Address details

The original IEEE 802 MAC address comes from the original Xerox Ethernet addressing scheme.[1] This 48-bit address space contains potentially 248 or 281,474,976,710,656 possible MAC addresses.

All three numbering systems use the same format and differ only in the length of the identifier. Addresses can either be "universally administered addresses" or "locally administered addresses".

A universally administered address is uniquely assigned to a device by its manufacturer; these are sometimes called "burned-in addresses" (BIA). The first three octets (in transmission order) identify the organization that issued the identifier and are known as the Organizationally Unique Identifier (OUI).[2] The following three (MAC-48 and EUI-48) or five (EUI-64) octets are assigned by that organization in nearly any manner they please, subject to the constraint of uniqueness. The IEEE expects the MAC-48 space to be exhausted no sooner than the year 2100;[3] EUI-64s are not expected to run out in the foreseeable future.

A locally administered address is assigned to a device by a network administrator, overriding the burned-in address. Locally administered addresses do not contain OUIs.

Universally administered and locally administered addresses are distinguished by setting the second least significant bit of the most significant byte of the address. If the bit is 0, the address is universally administered. If it is 1, the address is locally administered. In the example address 06-00-00-00-00-01 the most significant byte is 06 (hex), the binary form of which is 00000110, where the second least significant bit is 1. Therefore, it is a locally administered address.[4] Consequently, this bit is 0 in all OUIs.

If the least significant bit of the most significant octet of an address is set to 0 (zero), the frame is meant to reach only one receiving NIC.[citation needed] This type of transmission is called unicast. A unicast frame is transmitted to all nodes within the collision domain, which typically ends at the nearest network switch or router. Only the node with the matching hardware MAC address will accept the frame; network frames with non-matching MAC-addresses are ignored, unless the device is in promiscuous mode.[citation needed]

If the least significant bit of the most significant address octet is set to 1, the packet will still be sent only once; however, NICs will choose to accept it based on different criteria than a matching MAC address: for example, based on a configurable list of accepted multicast MAC addresses. This is called multicast addressing.

The following technologies use the MAC-48 identifier format:

The distinction between EUI-48 and MAC-48 identifiers is purely nominal: MAC-48 is used for network hardware; EUI-48 is used to identify other devices and software. (Thus, by definition, an EUI-48 is not in fact a "MAC address", although it is syntactically indistinguishable from one and assigned from the same numbering space.)

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 proprietary term EUI-48 should be used for this purpose.

EUI-64 identifiers are used in:

  • FireWire
  • IPv6 (as the least-significant 64 bits of a unicast network address or link-local address when stateless autoconfiguration is used)
  • ZigBee / 802.15.4 / 6LoWPAN wireless personal-area networks

The IEEE has built in several special address types to allow more than one network interface card to be addressed at one time:

  • Packets sent to the broadcast address, all one bits, are received by all stations on a local area network. In hexadecimal the broadcast address would be "FF:FF:FF:FF:FF:FF".A broadcast frame is flooded and arrived at all nodes. It is accepted by all nodes. See a Broadcasting Simulation video.
  • Packets sent to a multicast address are received by all stations on a LAN that have been configured to receive packets sent to that address.That is, a multicast frame is accepted by nodes that have the same multicast address. See a Multicast MAC Simulation video.
  • Functional addresses identify one or more Token Ring NICs that provide a particular service, defined in IEEE 802.5.

These are "group addresses", as opposed to "individual addresses"; the least significant bit of the first octet of a MAC address distinguishes individual addresses from group addresses. That bit is set to 0 in individual addresses and 1 in group addresses. Group addresses, like individual addresses, can be universally administered or locally administered.

In addition, the EUI-64 numbering system encompasses both MAC-48 and EUI-48 identifiers by a simple translation mechanism. To convert a MAC-48 into an EUI-64, copy the OUI, append the two octets "FF-FF", and then copy the organization-specified part. To convert an EUI-48 into an EUI-64, the same process is used, but the sequence inserted is "FF-FE". In both cases, the process can be trivially reversed when necessary. Organizations issuing EUI-64s are cautioned against issuing identifiers that could be confused with these forms. The IEEE policy is to discourage new uses of 48-bit identifiers in favor of the EUI-64 system.

IPv6—one of the most prominent standards that uses EUI-64—treats MAC-48 as EUI-48 instead (as it is chosen from the same address pool). This results in extending MAC addresses (such as IEEE 802 MAC address) to EUI-64 using "FF-FE" rather than "FF-FF".

Individual address block

An Individual Address Block comprises a 24-bit OUI managed by the IEEE Registration Authority, followed by 12 IEEE-provided bits (identifying the organization), and 12 bits for the owner to assign to individual devices. An IAB is ideal for organizations requiring fewer than 4097 unique 48-bit numbers (EUI-48).[5]

Bit-reversed notation

The standard notation, also called canonical format, for MAC addresses is written in transmission bit order with the least significant bit transmitted first, as seen in the output of the iproute2/ifconfig/ipconfig command, for example.

However, since IEEE 802.3 (Ethernet) and IEEE 802.4 (Token Bus) send the bytes (octets) over the wire, left-to-right, with least significant bit in each byte first, while IEEE 802.5 (Token Ring) and IEEE 802.6 send the bytes over the wire with the most significant bit first, confusion may arise when an address in the latter scenario is represented with bits reversed from the canonical representation. For example, an address in canonical form 12-34-56-78-9A-BC would be transmitted over the wire as bits 01001000 00101100 01101010 00011110 01011001 00111101 in the standard transmission order (least significant bit first). But for Token Ring networks, it would be transmitted as bits 00010010 00110100 01010110 01111000 10011010 10111100 in most significant bit first order. The latter might be incorrectly displayed as 48-2C-6A-1E-59-3D. This is referred to as bit-reversed order, non-canonical form, MSB format, IBM format, or Token Ring format as explained in RFC 2469. Canonical form is generally preferred, and used by all modern implementations.

When the first switches which supported both Token Ring and Ethernet came out, many switch vendors didn't understand this canonical form vs non-canonical form difference and as such there were numerous reports all over the world of duplicate MAC addresses. This was actually due to the switches from these vendors, which were not properly reversing the MAC addresses and thus causing the problem.[citation needed]

See also

References

External links


Wiktionary

Up to date as of January 15, 2010

Definition from Wiktionary, a free dictionary

Wikipedia-logo.png
Wikipedia has an article on:

Contents

English

Noun

Singular
MAC address
Plural
MAC addresss
MAC address (plural MAC addresss)
.
  1. (computing, networking) Media Access Control address.^ The MAC (Media Access Control) address is hardware address of a device connected to a network.
    • MAC Address - Glossary 23 January 2010 5:18 UTC www.opcti.com [Source type: General]

    ^ MAC is short for Media Access Control.
    • Information Management Systems & Services 23 January 2010 5:18 UTC www.imss.caltech.edu [Source type: General]

    ^ Media Access Control address .
    • MAC address@Everything2.com 23 January 2010 5:18 UTC www.everything2.com [Source type: General]
    • MAC address@Everything2.com 23 January 2010 5:18 UTC everything2.com [Source type: General]

    An OSI device layer address used by Ethernet, 802.11 wireless, Bluetooth, FDDI, ATM, and Fiber Channel networking technologies, all of which share the same address space, consisting of a globally unique number assigned to each network jack, wireless network radio, or other sort of network interface.

Translations

  • Finnish: MAC-osoite

See also

  • ARP
  • LAN
  • MAC-48
  • EUI-48
  • EUI-64

Citable sentences

Up to date as of December 13, 2010

Here are sentences from other pages on MAC address, which are similar to those in the above article.








Got something to say? Make a comment.
Your name
Your email address
Message