I'm under the impression that "Ethernet frames", at layer 2, in an Ethernet network are defined by the fact that they use Mac addresses to get the data to the right computer.

If that is the case then 802.11 b/g/n is also a type of Ethernet, isn't it? 802.11 NICs use Mac addresses in their frames too, don't they ??

802.3 defines ethernet:


802.3u - Fast Ethernet
802.3ab -Gig Ethernet

etc....


Your correct in saying that all ethernet adapters have a mac address or (BIA) Burned in Address. Its just not the mac address at layer 2 that allow hosts on the same broadcast domain to communicate. Ethernet is a Broadcast Multi-access network type, meaning it can support multiple hosts on the same segment and sits at Layer 2 of the OSI model. Ethernet relies on ARP (Address Resolution Protocol) to resolve layer 3 address's (Ip addresses) to layer 2 mac addresses. Without arp, the mac address and the ip address there there would be no communication with other hosts. When hosts on the same vlan (broadcast domain) communicate they can arp for each other directly. The source and destination mac address in the layer 2 headers do not change. When a host on a vlan wants to communicate with a host on a separate vlan then that traffic must be routed at layer 3. The upstream layer 3 device (router, firewall, layer 3 switch) re-writes the layer 2 frame header. The source mac is changed from the original host to the router's outgoing interface mac address and the destination is changed from the routers incoming interface mac address to the next hop routers receiving interface. This process continues until the destination hosts directly connected network is found. The layer 3 addresses do not change during this process.

So in short ARP is required on ethernet networks. If layer 3 to layer 2 resolution fails the overall communication with the host will fail. You cant have one without the other.


802.11 defines the Wireless Standards. Don't get them confused with the Ethernet standard's.

Ok, so while both Ethernet and 802.11 use Mac addresses in their Frames, there are OTHER factors that divide the two technologies.. Does that sum it up correctly ?

Correct, as both technologies have different encapsulation methods as well as the frame's themselves (how the frames are built and their structure) are different as well. You could look up the standards per the RFC for each to get more information.

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http://www.ine.com/self-paced/ccna/bootcamps.htm