Chapter 2: access to the network

Chapter 2: access to the network

1. there are two layers to support the network in all communication

   • apa of data link
     • prepare the data for the transmission and control the way in which these access the physical media.
     • data link layer protocol
       • purpose of the data link layer
         • • It allows the upper layers to access the media.
         • layer 2
           • The OSI data link layer is responsible for the exchange of Ethernet frames between the source and destination nodes through a physical network medium.
         • link sublayers
           • Logical link control (LLC)
             • this upper sublayer communicates with the network layer. It places information in the frame that identifies which network layer protocol is used for the frame.
           • Medium access control (MAC):
             • this is the lower sublayer, which defines the access processes to the medium that the hardware performs.
   • physical layer
     • transmits the frame to the data link layer for acceptance and processing.
       • physical layer connection
         • network interface cards
           • connect a device to the network.
     • purpose of the physical layer
       • provides the means of transport of the bits that make up a frame of the data link layer through the network means
       • layer media
         • Copper cable
           • the signals are electric pulse patterns.
         • Fiber optic cable
           • signals are light patterns.
         • Wireless connection
           • signals are microwave transmission patterns

2. types of connections

   • A physical connection can be a wired connection or a wireless connection using radio waves.
     • Media access control
       • topologies
         • topologies of wan
           • Point to point:
             • this is the simplest topology, consisting of a permanent link between two terminals
           • Hub-and-spoke:
             • is a WAN version of the star topology, in which a central site interconnects branch sites through point-to-point links
           • Mesh:
             • this topology provides high availability, but requires that each end system be interconnected with all other systems.
         • lan topologies
           • Star:
             • The first star topologies interconnected terminals through hubs.
           • Extended or hybrid star:
             • in an extended star topology, central intermediary devices interconnect other star topologies
           • Bus:
             • all end systems are linked together and end in some way at each end.
           • Ring:
             • the final systems connect to their respective neighbor and form a ring
         • data link frame
           • The data link layer prepares the packets for transport through the local media by encapsulating them with a header and a trailer to create a frame.
         • control of access to media
           • is the equivalent to the traffic rules that regulate the entrance of vehicles to a highway
             • Physical topology:
               • refers to physical connections and identifies how terminals and infrastructure devices, such as routers, switches, and wireless access points are interconnected
             • Logical topology:
               • refers to the way in which a network transfers frames from one node to the next. This arrangement consists of virtual connections between the nodes of a network.
   • type of physical connection
     • This type of configuration is called a wired network. The data is transmitted through a physical cable
   • wireless networks
     • the data is transmitted by radio waves.

3. CCNA1 TEL II CAP4 VARGAS

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