Good explanation in the replies. One note - if the MAC
address is 01 23 45 67 89 11 it is a multicast address
on Ethernet.
An odd number in the second nibble indicates a group
i.e. multicast address.
> First a computer does looks in it's arp (Address resolution protocol) cache
> to see if it already has an IP to MAC in it's database. If it does not the
> computer generally will do an ARP broadcast which all systems see and the
> computer using that ip address will respond with it's MAC address the Mac is
> stored in the cache and the frame is sent to that computer. If the IP
> address is not local, and the router see's the arp and has a destination to
> that IP or IP network it will respond with it's own mac and the frame will
> be delivered to the router who will then route it to the appropraite
> network/system.
>
>
>
>
> The first 6 are the manufacturer code.
>
>
>
> -----Original Message-----
> From: Oscar Rau [mailto:[EMAIL PROTECTED]]
> Sent: Tuesday, August 08, 2000 6:46 PM
> To: Cisco GroupStudy
> Subject: MAC address
>
>
> While an IP packet is being packaged to be delivered at the Ethernet frame
> stage,
> how is the destination MAC address determined? Is the destination MAC
> address going
> to be MAC address of the local gateway or the remote host?
>
> Is the MAC changed by the network devices (routers) along the way until it
> has been delivered to
> the destination Ethernet IP address?
>
> If a MAC address is,
>
> 01 23 45 67 89 11
>
> Which half is the vendor specific portion? Where would the multicast bit and
> locally
> administered MAC address bit be located?
>
> Thank you in advance.
> --
>
> Oscar Rau
> [EMAIL PROTECTED]
>
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