what is its frame structure?
The "frame" begins after the start frame delimiter with a frame header featuring source and destination MAC addresses and the EtherType field giving either the protocol type for the payload protocol or the length of the payload
Ethernet
The "frame" begins after the start frame delimiter with a frame header featuring source and destination MAC addresses and the EtherType field giving either the protocol type for the payload protocol or the length of the payload. 
where does the pfe reside on an mx960 router UNANSWERABLE what is juniper mx-series? It is a family of ethernet routers and switches what is the meaning of the initial word? Ethernet is a family of computer networking technologies commonly used in local area networks (LAN),  and wide area networks (WAN) when was it standardized? In February 1980 when was it introduced ? Ethernet was developed between 1973 and 1974 who developed it? It was inspired by ALOHAnet
wiki:1544275
Ethernet [SEP] Frame structure
In IEEE 802.3, a datagram is called a "packet" or "frame". "Packet" is used to describe the overall transmission unit and includes the preamble, start frame delimiter (SFD) and carrier extension (if present). The "frame" begins after the start frame delimiter with a frame header featuring source and destination MAC addresses and the EtherType field giving either the protocol type for the payload protocol or the length of the payload. The middle section of the frame consists of payload data including any headers for other protocols (for example, Internet Protocol) carried in the frame. The frame ends with a 32-bit cyclic redundancy check, which is used to detect corruption of data in transit.