Chapter 5 Flashcards
4 Physical Layer Function
- filter out signal disturbance caused by EMI and RFI
- amplify and reshape incoming signal
- retime the signal (in ethernet applications)
- reproduce the signal on all cable runs
Collision Domain
- segments where collisions occur
- caused by two or more nodes transmitting at once
Tasks Performed by MAU
- connect nodes in a logical ring through a physical star topology
- move the token and frames around the ring
- amplify data signals
- expand token ring network by daisy-chain connections
- provide for orderly movement of data
- shut down ports to malfunctioning nodes
3 Frame Scenarios
- destination of frame is on same segment as source; bridge drops frame (since no forwarding is needed
- destination of frame is on another segment known to bridge; bridge transmits frame to known segment only
- destination of frame is not known to bridge; bridge transmits frame to all segments but the source
3 Primary Bridge Functions
- learning
- filtering
- forwarding
Learning Bridge Function
- learn network topology and device addresses
- information is stored in a bridging table
Filtering Bridge Function
- do not flood certain frames, discard others
- enables the bridge to be used for security purposes
Forwarding Bridge Function
- transmit frames to destination
- based on data built-in to the bridging table
Advantages of Bridge over Repeaters & Hubs
- ability to segment network traffic
- may serve as a firewall to keep intruders out
Hop
- a regenerative, amplification, and movement of a packet from one network onto another by a router
Router
- connects two or more similar networks together
- protocols including routing protocol which uses information from routing table
Static Routing
- manually setting up and maintaining route
- always know path between routers
Dynamic Routing
- path between routers are unknown until you begin to send out packets
- routing tables are updated automatically
Routers Two Important Databases
- routing tables
- network status
Routing Table
- contains addresses of other routers
Network Status
- contains information about traffic, topology, and status of links
RIP
- Routing Information Protocol
- determines shortest number of hops to other routers
- only uses hop count as a metric
OSPF
- Open Shortest Path First
- sends only a portion of table related to immediate links
Advantages of OSPF over RIP
- routing information is packaged in a more compact format
- there is no hop count limit as with RIP
Cut Through
- forward portions of frame before entire frame is received
Store and Forward
- frame is buffered until entire frame is received
Gateway
- enables two networked systems (software or hardware) to connect
- convert common protocols to specialized type
WAN Transmission Devices
- telephone modems
- ISDN adapters
- Cable TV Modems
- DSL modems/routers
- Access Servers
- Remote Routers
Synchronous
- continuous data bursts controlled by a clock signal
Asynchronous
- discrete signal delimited by start and stop bits
ISDN Adapters
- connect PCs to ISDN lines with a terminal adapter
Terminal Adapter (TA)
- modem-like device
- converts digital signal for transmission over digital telephone line
Upstream
- transmit outgoing data, sound, TV signals
Downstream
- receive and blend incoming signals
Cable TV Modems
- maximum bandwidth reduced by other subscribers
DSL Modem and Routers
- works over copper wire likes ISDN
- dedicated DSL line is more secure
- dedicated DSL line provides full bandwidth for the link
Access Servers
- combines WAN communications into one device
- small access servers may have 8 or 16 asynchronous ports
Remote Routers
- similar to a local routers
