Troubleshooting Numbers for Ethernet

Locally Stored Copies:

Note! The locally stored copies are kept here to provide access when the network path to online copies is slow or down. The locally stored copies are out of date.

This page provides access to various troubleshooting numbers for Ethernet. These numbers include Type codes, vendor codes, LSAP/DSAP numbers, and multicast addresses.

If your Web browser supports a search feature, you can use it to search through these lists for a specific Type code, vendor code, or address.

The IEEE OUI List
The IEEE LSAP List
The Cisco LSAP List
Michael Patton's List of Ethernet Numbers

Online Access:

Online access is provided to download the latest copies of these documents. Be advised that FTP access may fail due to limits on the number of simultaneous users allowed at anonymous FTP servers.

FTP Access to the IEEE List of Organizationally Unique Identifiers (OUIs). Clicking here will retrieve the latest IEEE list of OUIs from the IEEE anonymous FTP server at ftp.ieee.org. The list is stored on the IEEE server as filename "info.stds.oui" in directory /info/stds.
Web Access to Michael Patton's List of OUIs and other Ethernet numbers. Clicking here will retrieve an online and up to date copy of these troubleshooting numbers.
FTP Access to the IEEE 802 Numbers of Interest. This list is an excerpt from the Assigned Numbers RFC. The most recent Assigned Numbers RFC is RFC1700.

What is it?

The Ethernet troubleshooting numbers are lists of Type codes, vendor codes, and multicast addresses that can help identify and track down machines and protocols in use on the network.

For example, the vendor codes make it possible to identify the manufacturer of a given Ethernet card. That can help you find out which machine on your network may be causing problems, by identifying the vendor of the Ethernet interface in the machine.

The Ethernet troubleshooting numbers are described in more detail this excerpt from the Network Reading List.

``The Ethernet frame specified by the DIX standard contains a Type field. The DIX Ethernet Type field contains a type number that describes the type of high-level network protocol (such as TCP/IP) being carried by the Ethernet frame. This information can be quite handy when you're troubleshooting a LAN problem and trying to figure out which high-level protocol may be involved.

In the new IEEE 802.3 frame specification, the type field was replaced by a more general, but more complex, set of frame specifiers. Nevertheless, many network software implementations still use the DIX frame specification with its accompanying Ethernet type field.

The addresses used in Ethernet frames are also useful to the network troubleshooter. The 48-bit Ethernet address is called an "Organizationally Unique Identifier" (OUI) and is divided into two 24-bit portions. The first portion is assigned to a specific manufacturer by the IEEE and the second portion is used by that manufacturer to create a unique address for each Ethernet interface.

If you know the manufacturer's number, you can frequently identify which computer may be causing network problems. This is not a foolproof mechanism, since some vendors may buy their boards from other manufacturers. Nonetheless, in many cases knowing the Ethernet addresses assigned to a manufacturer can help track down a malfunctioning device.''

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