When the computers on the network simply listen and receive the signal, they are referred to as passive because they don't amplify the signal in any way. Example for passive topology - linear

BUS topology:In this each computer is directly connected to primary network cable in a single line

Advantages:Inexpensive, easy to install, simple to understand, easy to extend

STAR topology:In this all computers are connected using a central hub

Advantages:Can be inexpensive, easy to install and reconfigure and easy to trouble shoot physical problems

RING topology:In this all computers are connected in loop

Advantages:All computers have equal access to network media, installation can be simple, and signal does not degrade as much as in other topologies because each computer regenerates it

Server-based network Server-based networks provide centralized control of network resources and rely on server computers to provide security and network administration

Peer-to-peer network Peer-to-peer network, computers can act as both servers sharing resources and as clients using the resources

The data unit in the LLC level is called the protocol data unit (PDU). The PDU contains of four fields a destination service access point (DSAP), a source service access point (SSAP), a control field and an information field. DSAP, SSAP are addresses used by the LLC to identify the protocol stacks on the receiving and sending machines that are generating and using the data. The control field specifies whether the PDU frame is a information frame (I - frame) or a supervisory frame (S - frame) or a unnumbered frame (U - frame)

In a baseband transmission, the entire bandwidth of the cable is consumed by a single signal. In broadband transmission, signals are sent on multiple frequencies, allowing multiple signals to be sent simultaneously