Ethernet
Last updated
Last updated
In the past, the Ethernet protocol required a coaxiale cable on which hosts interconnect. All the hosts electrically shared a bus.
In the past hosts ethernet interfaces were connected through a vampire tap junction.
Nowadays, the interfaces are connect to the cable using a T-junctions.
The difference between them is that the first one connects electrically to the cable (connecting it to a cable cut) and the second one is used only in ethernet cables that are physically composed by different cable (segments) and the T-junction is put at intersection of two segments.
The protocol supports Carriege Sense Multiple Access Collision Detection (CSMA/CD), used for coordination between hosts, that it's composed by two strategies:
Carrier sense An host can't speak while anyone else is speaking Collision detection the protocol resolves conflicts raised during the contention time.
Contention time the time in which people, that respect first rules, can also go in conflict starting talking together at the same moment.
Preamble synchronization signal 10101010...1010 011 where the last three bits are called SFD().
Destination address & Source address MAC (Medium Access Control) addresses, that are Hardware identifiers (broadcast= ff:ff:ff:ff:ff:ff ).
Type type of upper layer protocol used (e.g. Internet Protocol = 0x0800 ).
Payload payload of the ethernet frame.
FCS Frame check sequence (FCS) is a CRC that allows detection of corrupted data within the entire frame as received on the receiver side.
