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Ethernet Numbers
What are Ethernet Numbers?
The Ethernet numbers include the 48-bit media access control (MAC)
address assigned to each Ethernet interface, and the 16-bit value used
in the Type field of the Ethernet frame.
MAC Addresses
Each Ethernet interface is assigned a unique MAC address at the time
of manufacture. The first 24 bits of the MAC address consist of an
Organizationally Unique Identifier (OUI) assigned to a vendor by the
IEEE, which is why they are also called vendor codes. The Ethernet
vendor combines their 24-bit OUI with a unique 24-bit value that they
generate to create a unique 48-bit address for each Ethernet interface
they build.
Type Codes
An Ethernet Type code is a 16-bit number carried in the Type field of
the Ethernet frame. This number is used to identify the type of
high-level network protocol packet that is being carried in the data
field of the Ethernet frame.
Troubleshooting with Ethernet Numbers
OUI (vendor) codes and Type codes can help identify and track down
machines and protocols in use on the network.
For example, the OUI codes can help identify the vendor of a given
Ethernet card that may be sending incorrect traffic. Knowing the
vendor can often help you find out which machine on your network may
be the one causing problems.
- Search the
IEEE Organizationally Unique Identifiers (OUIs). This IEEE
page provides search access to their list of OUIs and also provides
download access to the entire IEEE OUI list. Note that the IEEE list
of OUIs is not complete, since vendors can request not to be
publically listed. This page also describes how to apply for an OUI
of your very own, which costs US $1,250 as of this writing.
- IEEE
tutorial on Organizationally Unique Identifiers (OUIs). This
brief IEEE tutorial describes the use of OUIs in LANs and MANs.
- IEEE
Type Field page. This IEEE page provides a public list of Type
field assignments and the organizations which requested them. This
list only identifies the organizations who have requested a Type field
for use in their work on protocol development. Michael Patton's list
should be consulted for the actual Type identifier used for a given
protocol.
- Michael
Patton's List of OUIs and other Ethernet numbers. Michael
Patton's list of OUIs was created by volunteers who sniffed packets on
their networks and recorded the OUIs. This list may be more complete
than the IEEE list for older OUIs, but since it does not appear to be
actively maintained it is probably out of date.
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Ethernet numbers from IANA. Maintained by the Internet
Assigned Numbers Authority (IANA), this list includes assigned
multicast addresses.
- IEEE LSAP
List List of Link Service Access Point (LSAP) numbers assigned
by the IEEE. LSAP numbers are used when sending 802.2 logical link
control (LLC) data in 802.3 frames with a frame Length field instead
of an Ethernet Type field. The 802.2 LLC scheme uses Service Access
Point identifiers instead of Type fields to identify the type of data
being carried over the network.
- IANA
list of LSAPs
- The Cisco LSAP List
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