simple question

Layer 2 - MAC Address, 48 bit unique identifier for a network host participating in an network. MAC address does not imply the network is Ethernet.

Layer 3 - IP Address, 32 bit identifier for a host participating in a IP network.

Beyond that, I would suggest Google.

-mike

Lukasz wrote:

Not always 48 bit. Can be more, can be less.

Ever seen what MS RAS server sends for mac addresses in DHCP requests over ethernet?

Also, arcnet has 8 bit mac addresses. (just one of the many reasons it's a dead technology)

T. Sean Weintz

Nope. I'm almost afraid to ask, what does MS RAS Server send?

A typical one might look something like:

notice it's 16 bytes instead of the usual 6.

The first four bytes are always 52:41:53:20. Try converting that to ascii and you will see why they chose those bytes ;-)

This has apparently changes since they released wink. But NT3.5 and 4.0 RAS do use those funny MAC addresses.

And that doesn't break anything?

Only 48 bit addresses conform to the Ethernet/IEEE 802.3 standard, however, that is not the only MAC in the world. As other posters noted, ARCnet used 8 bit MAC addresses as did Apple's LocalTalk (although they didn't call them "MAC" addresses).

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The usual micros~1 ``let's break stuff'' attitude. I always filter on exactly that with my dhcp setup. Then again, I am not forced to run that kind of stuff, so anything looking like it is clearly rogue.

It did have some nice ideas, though.

Is that off-by-one-error intentional?

Apart from filling up all of the DHCP pool if you let it? Apparently the protocol is robust enough to deal with it. Admittedly, I have not dug into its spec to find out if it's legal or not.

A mac address is assigned to a network card at the point of manufacture. An IP address is assigned, when a computer is connected to a network. The mac address is used for communication over a local network. An IP address is used when the data has to pass through a router.