1. Another Acronym For Mac Address Is The Bia
A MAC may be referred to as the burned-in address (BIA). It may also be known as an Ethernet hardware address (EHA), hardware address or physical address (not to be confused with a memory physical address). A network node may have multiple NICs and each NIC must have a unique MAC address. MAC is the acronym for Media Access Control. Its address is a unique code made up of 12 (XX:XX:XX:XX:XX:XX) characters for a particular hardware like say the network adapter of WiFi devices. In my wireless table of who is connected to the wireless network there are 3 different mac addresses displaying when there is only two computers in the house(its not an outsider, it only shows when the other pc turns on), 2 of them have the same computer name but are connected at different IP addresses(192.168.1.101,192.168.1.102). Suppose f0/0 and f0/1 of a router would have the same MAC address, you would not be able to connect them to the same L2 domain. The switch would learn the MAC-address on two ports and report 'mac-flapping' On logical interfaces (which obviously connect to the same switchport and the same L2 domain) the only issue I am aware of is with DHCP.
Earlier most routers and switches would allocate a unique MAC address for every subinterface/SVI. This was a waste of resources though. Now they will mostly use the same MAC-address. At least if the subinterfaces are located under the same physical interface. Here is a quick test I did in GNS3. I created 3 subinterfaces under the same physical interface. Tablet for mac cad.
R1#sh int i Fast bia FastEthernet0/0 is up, line protocol is up Hardware is Gt96k FE, address is c200.1b38.0000 (bia c200.1b38.0000) FastEthernet0/0.1 is up, line protocol is up Hardware is Gt96k FE, address is c200.1b38.0000 (bia c200.1b38.0000) FastEthernet0/0.2 is up, line protocol is up Hardware is Gt96k FE, address is c200.1b38.0000 (bia c200.1b38.0000) FastEthernet0/0.3 is up, line protocol is up As you can see the MAC address is the same and that is fine. The router terminates the VLAN so it does not matter that MAC address is the same. Hi Ernie, Can you point us to the Video# in which this was explained? Thanks, Erwin On Sat, Dec 17, 2011 at 1:00 AM, Ernie_07 wrote: > My understanding is that a SINGLE mac address can be associated with an > interface. Thus a layer 2 packet rewrite associated with ANY subinterface > will always use the mac address of the physical interface.
1 Another Acronym For Mac Address Is The Bianchi
The new streaming > CCNA that I reviewed indicated that a separate mac address will exist for > each subinterface. If I am to develop a proper foundation for CCIE study, I > must master important details and banish common assumptions. Clarification > will be appreciated. > > Ernie > > > > > Internetwork Expert - The Industry Leader in CCIE Preparation >. Hi Erwin, Daniel has shed some light upon my confusion. He pointed out that older routers provided unique mac addresses for subinterfaces while newer ones assign the mac address of a physical interface to each of its subinterfaces. This appears to be a hardware-dependent issue rather than an error within the CCNA VOD.