IEEE Registries#
EtherLyzer maintains local copies of supported IEEE Registration Authority datasets and uses them for local identifier lookups.
Supported registry types#
Registry |
Category |
Purpose |
|---|---|---|
MA-L |
MAC |
MAC Address Block Large |
MA-M |
MAC |
MAC Address Block Medium |
MA-S |
MAC |
MAC Address Block Small |
IAB |
MAC |
Legacy Individual Address Block |
CID |
Identifier |
IEEE Company Identifier |
EtherType |
Protocol |
Ethernet protocol identifier |
EUI-48 assignment sizes#
Type |
Prefix bits |
Address bits |
Addresses |
|---|---|---|---|
MA-L |
24 |
24 |
16,777,216 |
MA-M |
28 |
20 |
1,048,576 |
MA-S |
36 |
12 |
4,096 |
IAB |
36 |
12 |
4,096 |
The prefix and address sizes above refer to allocations within the 48-bit EUI-48 address space.
MA-L#
MA-L, or MAC Address Block Large, uses a 24-bit assignment prefix and provides 24 bits of address space.
An MA-L assignment includes an IEEE Organizationally Unique Identifier (OUI).
Prefix Address space
24 bits 24 bits
────────────┬────────────────────────
00:11:22 │ xx:xx:xx
This provides 16,777,216 EUI-48 addresses per assignment.
MA-M#
MA-M, or MAC Address Block Medium, uses a 28-bit assignment prefix and provides 20 bits of address space.
Prefix Address space
28 bits 20 bits
────────────────┬────────────────────
00:11:22:3 │ x:xx:xx
This provides 1,048,576 EUI-48 addresses per assignment.
Unlike MA-L, an MA-M assignment does not include an OUI.
MA-S#
MA-S, or MAC Address Block Small, uses a 36-bit assignment prefix and provides 12 bits of address space.
An MA-S assignment includes an IEEE OUI-36.
Prefix Address space
36 bits 12 bits
────────────────────────┬────────────
00:11:22:33:4 │ x:xx
This provides 4,096 EUI-48 addresses per assignment.
IAB#
IAB, or Individual Address Block, is a legacy 36-bit assignment type providing 4,096 EUI-48 addresses.
The IAB registry is no longer active and was replaced by MA-S. Existing IAB assignments remain valid and may still appear in historical and currently deployed hardware.
EtherLyzer retains IAB registry data so these assignments can still be resolved and inspected.
CID#
CID, or Company Identifier, is a globally unique 24-bit identifier assigned by the IEEE Registration Authority.
Unlike an OUI, a CID cannot be used to generate universally unique EUI-48 or EUI-64 addresses.
CID is intended for applications where an organization requires a globally unique identifier without requiring globally unique MAC addresses.
EtherType#
An EtherType is a 16-bit protocol identifier used to indicate the protocol carried by an Ethernet frame.
Common examples include:
EtherType |
Protocol |
|---|---|
|
IPv4 |
|
ARP |
|
IPv6 |
|
IEEE 802.1Q VLAN |
Local registry data#
EtherLyzer performs lookups against synchronized local IEEE registry data rather than sending identifiers to third-party lookup services.
Internet access is only required when the local registry data needs to be synchronized.