"Aaron" <[EMAIL PROTECTED]> wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> Hi, everyone!
>
> I have a question about the MAC layer address, and I use the Ethernet for
> making an example.
>
> We all know that the first 3 bytes of the 48-bit MAC address are indicate
> the vendor. Among the 3 bytes, the first is important, because the first
2-
> bit in this byte has special meanings that are I/G bit and U/L bit.
>
> I have a question about the following whether it is right:
> when we get a MAC address, such as 0030.b6f7.3000 (Cisco),
> 1. Whether the I/G and U/L bit are already set to zero?
> 2. When a multicast packet shoud be sent to this address, the destination
> address in the MAC packet header should be set to 0130.b6f7.3000?
Wouldn't a multicast packet be sent to the MAC address of the multicast
group, as translated from the multicast IP address, not to the individual
host's MAC address (or an alteration thereof)? If so, the first three bytes
are 0100.5e, with the remainder determined by the translation of the
multicast IP address. Then, if it was, say, an all routers multicast, the
destination MAC would be 0100.5e00.0002
Or am I missing something important in the question?
---JRE---
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