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PPPoE missing things in the ethernet frame.

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julian403

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Hello, reading the RFC 2516 documents which describe PPPoE it took my attention the frame

220px-Uno.png


Where we can see that the PPP frame is encapsulated in the payload ethernet. But there are missing the preamble and the SFD header. Why that? the preamble and SFD are totally necessary to the synchronization in other way the ethernet port (That we can say that the the RF 1:1 transformer there is a flip flops types D in series which form the register and which need the sincronization to works and for that I means the clock)

so, Why in an RF documents is missing something so important? or really really they are not there in the frame for some reason? it they are not in the pictures due it's not data?

Please, this is the documents where you can read it:https://datatracker.ietf.org/doc/rfc2516/?include_text=1

and it says this:

Capture1.JPG
 

Considering the layered protocol specification, you shouldn't expect the ethernet frame definition in RFC 2516. It's specified in IEEE 802, some fields vary according to the used transport medium.
 
Thanks. But as you said its' specified in IEEE802.3 so it's not necessary to do it again? thats do you means? becaus, taking in account RFC2516 frame without the preamble, how the package is syncronizated?
 

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