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