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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


Define Routing

Deciding the overall path for packet/ frame through the network from source to destination through multiple hops/trans


Define Forwarding

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
(ARP request)
- MAC/ IP cached together
- expires after a few minutes to allow mapping change


What is the Dynamic Host Configuration Protocol?

in IPv6,
- 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?

- Addressing
- 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


What is the transmission (sliding window) policy?

decouples acks and recvr buffer allocation; delayed acks; special algorithms to control with data is sent