6.1
OSI and TCP/IP:
OSI model (transport) ≈ TCP/IP model
(host-to-host)
OSI model (network) ≈ TCP/IP model
(internet)
OSI model (data link, physical) ≈ TCP/IP
model (network access)
OSI layer work with OSI layer, every layer
will add its own information in the data.
People can read application and
presentation layers information, other layers are computer’s job.
TCP: safety, reliability, high system cost
(handshake first)
UDP: fast, low cost, but unsafety
0~1023 well-know ports, 1024~49151
registered ports, 49152~65535 dynamic ports.
6.2
Types of Transmission:
Long distance, digital is better than
analog. If using analog, you need a model to transfer analog to digital,
because computers only can read “0” and “1”.
Synchronous: robust error checking, timing component,
high-speed and high-volume, low cost
Asynchronous: no timing component, processing
every byte, error controlling every byte (three steps: start, stop, parity)
Baseband: every time only transport one
information
Broadband: can transport several information
at same time.
6.3 Cabling,
Networking Foundations and Media Sharing:
Attenuation: gradual loss in intensity of
any kind of flux through a medium.
Crosstalk: the signal from one cable goes
to other cable.
Ring topology: each system connect to two
other system, forming a single, unidirectional network pathway for signals,
thus forming a ring.
Bus topology: systems are connects to a
single transmission channel, forming a linear construct.
Star topology: network consists of one
central device, which acts as a conduit to transmit messages.
Mesh topology: network where each system
must not only capture and disseminate its own data, but also serve as a relay
for other system.
Ethernet: 802.3 and using 48-bit MAC
addressing
Token ring: controls network communication
traffic through the use of token frames. It replaced by Ethernet.
6.4
Transmission Methods, Network Protocols, and Domain Name Service (DNS):
Internet group management protocol (IGMP):
the protocol between rout and system on the IP network.
Media access control (MAC): data
communication protocol sub-layer of the data link layer specified in the OSI
model.
Address resolution protocol (ARP): a
networking protocol used for resolution of network layer IP addresses into link
layer MAC addresses.
DNS: a hierarchical distributed naming
system for computers, sevices, or any resource connected to an IP based
network.
6.5
Network Devices and firewalls:
Repeaters: it repeats electrical signals
between cable segments which enable is to extend a network.
Bridges: LAN device used to connect LAN
segments.
Routers: checking routing data, finding IP address,
sending requested destination IP, Check destination IP is right or wrong,
fragments the datagram, changing header information and making packet, sending
the packet to its output queue for the necessary interface
Dual-homed firewall: two interfaces and
sits between an untrusted network and trusted network to provide secure access.
Virtual firewall: running in the
virtualized environment, control and monitor data in virtual machines.
Cloud computing: sharing resources,
software, and information
6.6
Network Type:
Electronic data interchange: structured
transmission of data between organizations.
Value-added network: a hosted EDI service
Metropolitan area network: such as campus
network
Metro Ethernet: it used to connect larger
network service or internet
Wide area network: a telecommunication
network that covers abroad area
6.7
Wireless Technology:
First generation: analog services, voice service
only
2G: primarily voice, some low-speed data,
phones were smaller in size, added functionality of e-mail, paging and caller
ID
2.5G: 2G + email and web pages
3G: integration of voice and data,
packet-switched technology
3.5G: OFDMA (Orthogonal
Frequency-Division Multiple Access is a multi-user version of the popular orthogonal
frequency-division multiplexing (OFDM) digital modulation scheme)
4G:
based on an all-IP packet-switched network, data exchange at 100mbps – 1Gbps
没有评论:
发表评论