OSI Data-Link with Ethernet Frame

ulviallahverdi

Hello, I have question about OSI model's Data Link Protocol : Ethernet Frame

I am preparing for CCNA . And i am reading CCNA book. in There , there is ethernet frame topic ,everything is fine.But i have big understanding problem with Ethernet Frame.

Actually cisco says that and also in everywhere say that :
Data-Link Layer of OSI model frame like as follow:

|L2 HEADER| |DATA| |L2TRAILER|

but when ethernet frame use in everywhere frame is being shown like:

HEADER TRAILER

|PREAMBLE| |SFD| |Destionation| |SOURCE| |TYPE| |DATA AND PAD| |FCS|


Everything is good , but this frame must start with | L2HEADER| , where is it? It just starts with ETHERNET HEADER where is data-link header?

Help me please

d4nz1g

hi mate

Ethernet is a data link protocol. Thus, the ethernet header is a data link header. the Ethernet frame header is composed of dst.addr, src.addr and ethertype. in vlan tagged frames, there is also an ethertype (for the vlan field) priority, CFI and vlan id.

an illustration to help:

https://ciscohite.files.wordpress.com/2013/05/802.png

negru_tudor

ulviallahverdi wrote: »

Hello, I have question about OSI model's Data Link Protocol : Ethernet Frame

I am preparing for CCNA . And i am reading CCNA book. in There , there is ethernet frame topic ,everything is fine.But i have big understanding problem with Ethernet Frame.

Actually cisco says that and also in everywhere say that :
Data-Link Layer of OSI model frame like as follow:

|L2 HEADER| |DATA| |L2TRAILER|

but when ethernet frame use in everywhere frame is being shown like:

HEADER TRAILER

|PREAMBLE| |SFD| |Destionation| |SOURCE| |TYPE| |DATA AND PAD| |FCS|


Everything is good , but this frame must start with | L2HEADER| , where is it? It just starts with ETHERNET HEADER where is data-link header?

Help me please

Think of the entire [PREAMBLE - SFD - DEST - SOURCE - TYPE] Ethernet frame portion as the OSI L2 Frame header. the [FCS] part would be your OSI trailer

ulviallahverdi

Ahaa ok ,Thanks d4nz1g,negru_tudor .
It means i dont need to see HEADER of DATALINK itself. when ethernet frame is using it means it is also Data-Link header and trailer.
And i'd like to ask from which layer transmit or recieve?