Chapter_3 Flashcards
what is another term for a serial connection or leased line?
point to point connection
where are point to point connection used?
to connect a LAN to a WAN, ISP or another LAN within a business.
difference between serial and parallel communication?
serial communications allow data to travel both directions but only one bit at a time over one link while, parallel communication allows several bits to travel at once but only in one direction and often are more expensive and used in older HDD’s, printers, etc. (*cross-talk is an issue over large distances.)
what are the top 3 serial connection standards used?
RS-323
V.35
HSSI (High speed serial interface)
what is the serial connection RS-323?
older serial port connections for peripherals.
what is the serial connection V.35?
uses the DSU (Data Service Unit) to convert line frames into frames that the LAN devices can read and vice versa. *uses modem to multiplexer communication. combines bandwidth of several telephone lines.
what is the serial connection HSSI?
HSSI: high Speed Serial Interface-
connects router on LAN’s to WAN’s over high speed lines like, T3. The interface used is DTE/DCE. token ring or Ethernet is used.
DTE is what?
DTE: Data Terminal Equipment-
connects customer LAN to the WAN on the local loop through the DCE - Data Communications Equipment.
DCE is what?
Data Communications Equipment-
puts data onto the local loop. end of the WAN side of communication facility. responsible for providing clocking signal.
CHAP?
Challenge Handshake Authentication Protocol
PAP?
Password Authentication Protocol.
PPP?
Point to Point protocols
describe when PPP is used and what it does?
Point to Point Protocol: used to connect serial/ leased lines from a LAN to a WAN ISP. **able to handle authentication, compression, error detection and can bundle several connections together to share load.
what are some serial ports used?
RS-232 (older type, also called RJ-45) new type is the: USB universal serial bus.
* V.35: used for modem to multiplexer communication. used by most routers and DSU’s (Data service units) to connect to T1 carriers.
what is HSSI?
High-Speed Serial Interface
what is time division multiplexing? what are the 2 types?
TDM Time division multiplexing, STDM Statistical Time Division Multiplexing.
**used to allow multiple logical signals to share a single physical line.
describe what TDM is?
Time Division Multiplexing: a muttiplexer takes several singnals from a network and combines those into several channels (time slots) that then traverse 1 physical link over a serial connection to a destination multiplexer. the destination device takes those channels and splits the data up into original separate paths to end networks/devices. TDM allocates channel spaces even if those spaces are not filled with data. a timing clock system is used to do this.
bit interleaving?
used by a Mux: multiplexer: keeps track of the number and sequence of the bits from each specific transmission so that they can be quickly and efficiently reassembled into their original form upon receipt
STDM? describe it:
Statistical Time-Division Multiplexing:
the time length is Variable… this means that any empty channels/ time allocated slots are up for grabs by neighbor channels so that there are no empty time slots and this increases the efficiency of the connection. each transmission carries a channel identifier since the channels are variable length.
SONET?
Synchronous Optical Networking
-time division multiplexing data that is sent over fiber-optics in north america. uses STDM: synchronous Time Division Multiplexing.
SDH?
Synchronous Digital Hierarchy
-transports TDM time division multiplexing data in other parts of world.
Demarcation point:
the point in the network where the ISP responsibility ends.
CSU/DSU
Digital-leased lines require a CSU and a DSU. A CSU/DSU can be a separate device like a modem or it can be an interface on a router. The CSU provides termination for the digital signal and ensures connection integrity through error correction and line monitoring. The DSU converts the line frames into frames that the LAN can interpret and vice versa.
*Channel Service Unit/ Data Service Unit
CPE?
Customer Premises Equipment (CPE) : company uses WAN services from an ISP and uses a device called the CPE by renting or owning it and it is connecting the business to the carrier link.
