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hardware address是mac地址吗( 二 )

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另外，你也可以在"设置管理器"中，打开网卡的属性页来修改，效果一样 。WINXP的修改方法跟WIN2000一样 。
在98下面修改和WIN2000、XP下差不多 。在"网上邻居"图标上点右键，选择"属性"，出来一个"网络"对话框 ， 在"配置"框中 ， 双击你要修改的网卡，出来一个网卡属性对话框 。在"高级"选项中，也是点击"属性"标识下的"Network Address"项，在右边的两个单选项中选择上面一个，再在框中输入你要修改的网卡MAC地址，点"确定"后，系统会提示你重新启动 。重新启动后 ， 你的网卡地址就告修改成功?。?br> 如果你想把网卡的MAC地址恢复原样，只要再次把"Network Address"项右边的单选项选择为下面一个"没有显示"再重新启动即可 。在WIN2000、XP下面是选择"不存在"，当然也不用重新启动了 。
In computer networking a Media Access Control address (MAC address) or Ethernet Hardware Address (EHA) or hardware address or adapter address is a quasi-unique identifier attached to most network adapters (NIC or Network Interface Card). It is a number that serves as an identifier for a particular network adapter. Thus network cards (or built-in network adapters) in two different computers will have different MAC addresses, as would an Ethernet adapter and a wireless adapter in the same computer, and as would multiple network cards in a router. However, it is possible to change the MAC address on most of today's hardware, often referred to as MAC spoofing.
Most layer 2 network protocols use one of three numbering spaces managed by the Institute of Electrical and Electronics Engineers (IEEE): MAC-48, EUI-48, and EUI-64, which are designed to be globally unique. Not all communications protocols use MAC addresses, and not all protocols require globally unique identifiers. The IEEE claims trademarks on the names "EUI-48" and "EUI-64" ("EUI" stands for Extended Unique Identifier).
MAC addresses, unlike IP addresses and IPX addresses, are not divided into "host" and "network" portions. Therefore, 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.
ARP is commonly used to convert from addresses in a layer 3 protocol such as Internet Protocol (IP) to the layer 2 MAC address. On broadcast networks, such as Ethernet, the MAC address allows each host to be uniquely identified and allows frames to be marked for specific hosts. It thus forms the basis of most of the layer 2 networking upon which higher OSI Layer protocols are built to produce complex, functioning networks.
Contents [hide]
1 Notational conventions
2 Address details
2.1 Individual address block
3 Bit-reversed notation
4 See also
5 References
6 External links
[edit] Notational conventions
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. Other conventions include six groups of two separated by colons (:), e.g. 01:23:45:67:89:ab; or three groups of four hexadecimal digits separated by dots (.), e.g. 0123.4567.89ab; again in transmission order.
[edit] 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). 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; 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. The bit is 0 in all OUIs. For example, 02-00-00-00-00-01. The most significant byte is 02h. The binary is 00000010 and the second least significant bit is 1. Therefore, it is a locally administered address.[2]


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