Flashcards in New Contect Deck (20):
Define: Transport Entity
Hardware/ Software providing services
Why is the transport layer necessary?
IP as network layer is "best effort" so we need transport layer for reliable service
What is the key difference between the data link and network layer
Data layer moves frames from one end of a wire to the other, while network layer moves packets globally from source to destination using multiple hops
What must the network layer know and choose?
must know the topology of the network and choose appropriate paths accordingly
Deciding the overall path for packet/ frame through the network from source to destination through multiple hops/trans
Local decision made within a router to choose appropriate outgoing link for a given pack/ frame as part of overall path
What is important for the routing algorithm?
Correctness important, robustness critical
Fairness and efficiency are also desirable
What is the most effective congestion control?
reducing network load cooperatively by network and transport layers
What are some issues to consider for achieving the quality of service with less?
application requirements, regulation of traffic, resource reservation, traffic acceptance margin
What does the network layer do?
Provides services to the transport layer at the network layer/ transport layer interface
Provides end-to-end packet delivery using datagrams or virtual circuits
What are the 5 parts of link state routing?
1. Discover its neighbors and learn their network addresses
2. Determine the link cost (to each of its neighbors)
3. Preoparation of link state packets
4. Distributed Link State Packets
5. Local Shortest-path computation
What is the IP Address Resolution Protocol?
in IPv4, enables association of MAC and IP addresses
- When host only has IP addr of destination, broadcases an inquiry to identify owner, which will be the sole responder, providing its MAC address
- MAC/ IP cached together
- expires after a few minutes to allow mapping change
What is the Dynamic Host Configuration Protocol?
- every server has a designated DHCP server
- New host broadcasts a 'DHCP discover' request, which must reach server
- server responds with 'DHCP' offer pack that provides an available IP address for host
- addres not permanent
What is the transport layers purpose?
to provide a reliable service on top of an unreliable network
What are the 5 basic primitives of the transport layer?
Listen, connect, send, recieve and disconnect
What are elements of the transport protocols?
- connection establishment
- connection release
- error/ flow control
- multiplexing and inverse multiplexing
- crash recovery
Where is conjecstion detected and controlled? and how
Detected in network layer (routers) and controlled in transport layer (hosts) by reducing rate of entry of packets to network
What does the user datagram protocol do?
provides a way for applications to send encapsulated IP datagrams without having to establish a connection
- unreliable with no set up
What does the transmission control protocol provide?
Reliable service through setup (whereas UDP is unreliable with no setup)
Provide reliable end-to-end byte stream over unreliable inter network