W7 Flashcards
Data is divided into two layers:
- Logical Link Layer
- Media Access Layer
CSMA/CD Protocol - CS:
Carrier Sense:
Each computer NIC listens to the noise level on the line, when the noise is low, it sends data.
CSMA/CD Protocol - MA:
Multiple Access:
Nothing preventing 2 computers to send data at the same time, if they do, collision and data is lost.
CSMA/CD Protocol - CD:
Collision Detection:
Each computer NIC listens to the noise level and if it detects a spike in noise, a collision has occurred. Both devices stop sending, special packet sent to delete transmission.
CSMA/CA:
Carrier Sense Multiple Access/Collision Avoidance:
The station ready to transmit a frame, senses the medium by checking the energy level at the carrier frequency.
IFS:
Interframe Space:
Collisions are avoided by deferring transmission even if the channel is found idle. When an idle channel is found, the station does not send immediately. It waits for a period of time called IFS.
Contention window:
An amount of time divided into slots.
Acknowledgment:
There may still be a collision, and data may also be corrupted during the transmission.
Switch:
Networking hardware that connects devices on a computer network by using packet switching to receive and forward data to the destination device.
Two fundamental techniques of switching:
Circuit Switching
Packet Switching
Circuit Switching:
Requires establishing a path, transmitting the data and disconnecting the circuit.
Packet Switching:
Most popular form of connection.
- Large messages fragmented into smaller messages, each one individually addressed
- On demand resource allocation.
Includes datagram switching (network layer), and virtual circuits (datalink layer)
Router:
- Determines best path for packet
- Internet Layer Device
- Connects multiple IP networks to exchange packets
- Many alternate paths
- Maintains routing table for finding best path
Subnet mask:
Divides the IP address into a network address and host address. One part identifies the host (computer), the other part identifies the network to which it belongs.
Traditional Network devices:
- Control Plane and Data Plane are in same hardware
- All the network devices were controlled separately
Network Virtualization:
- Control Plane and Data Plane are separated
- Control Planes are centralized virtually under SDN (software development network)
- Network administrator can manage, add, modify networking activities very fast
- Improved cloud networking and security.
Network Virtualization (NV) Benefits:
- Increase time of network supplying from weeks to minutes
- With automation, greater efficiency in network operation is achieved
- Network workloads can be placed separate from the physical topology
- Improved networking security
MPLS:
Multiprotocol Label Switching:
- Switches that function at layer 3
- Adds MAC address to frame to pass frame to next link
- Must recalculate the FCS (Frame Check Sequence)
- Simplifies routing by making it more like switching
HOW MPLS sends a packet:
- Calculates best route called “label-switched path”
- Path assigned to unique address
- MLPS header added between LAN and IP header
- Each address unique within the data network
VOIP:
Voice over Internet Protocol:
- VoIP apps growing in business sector
- Business deals with one network
- Increases mobility
- Increases worker collaboration
- Improves customer relations
VoIP Applications - Client/Server Architecture:
- Requires real time transmission
- Uses UDP (user datagram protocol) combined with RTP (real time protocol)
- Adds header between UDB header and application message
- Header adds a sequence number and timestamp to avoid jitter
