Re: New LINKTYPE_ for EPON

[Guy Harris <guy () alum mit edu>]

On Apr 21, 2014, at 6:38 AM, Philip Rosenberg-Watt <P.Rosenberg-Watt () cablelabs com> wrote:

> The frames as captured do not look like they've passed through the receive
> function. Here's an example preamble as captured:
>
> D5 55 55 3C 02 44
>
> As you can see, The first two bytes of the preamble have been stripped
> according to the note in 65.1.3.2.1 "SLD." The first byte we get to see,
> which is the third byte of the preamble, is the SLD 0xD5. Then two bytes
> of 0x55, then the LLID 0x3C02, then the CRC-8 0x44.
>
> Everything after those 6 bytes is a normal Ethernet frame, starting with
> the destination MAC.

        ...

> So I believe we will only need one LINKTYPE_ which will be for EPON frames
> that have not been processed by the receive function (or straight off of
> the optical fiber).

OK, so frames for LINKTYPE_ETHERNET_P2MP, or whatever we end up calling it, are:

        the last 6 octets of the modified preamble as specified by 65.1.3.2 "Transmit" in 802.3-2012

followed by

        a regular Ethernet frame (with the destination MAC being the MAC of the splitter, rather than the MAC of the 
final destination?)?

> Any sniffing after an EPON preamble has been processed
> through the receive function will appear to be a normal Ethernet frame.

And those would be LINKTYPE_ETHERNET, with just a regular Ethernet frame with the right destination MAC, and nothing 
preceding the destination MAC?
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