Networking Transmission Rate Quiz

Network Layer Performance

• The performance of a network can be measured in terms of delay, throughput, and packet loss.
• Congestion control is an issue that can improve the performance of a network.

Delay

• Delay is the time a packet takes to travel from its source to its destination.
• There are four types of delay:
  • Transmission delay: the time a sender needs to put the bits in a packet on the transmission media one by one.
  • Propagation delay: the time it takes for a bit to travel from point A to point B in the transmission media.
  • Processing delay: the time required to process a packet in a router.
  • Queuing delay: the time the packet waits in a router's queue.

Throughput

• Throughput is the number of bits passing through a point in a network in a second.
• Throughput is the transmission rate of data at a point in a network.
• In a path with n links in series, the throughput is the minimum of the transmission rates of the individual links.

Packet Loss

• Packet loss is the number of packets lost during transmission.
• Packet loss can occur when a router receives a packet while processing another packet, and the received packet needs to be stored in the input buffer waiting for its turn.
• When the input buffer is full, the next packet needs to be dropped, which can cause more packet loss.

Congestion Control

• Congestion control is a mechanism for improving network performance.
• Backpressure is a congestion control mechanism used in virtual-circuit networks.
• In backpressure, a node informs its upstream node to slow down when it is congested.
• A choke packet is a packet sent by a node to the source to inform it of congestion.

Packet Switching

• Packet switching is a data communication switching technique used in the network layer.
• There are two approaches to packet switching: datagram (connectionless) approach and virtual-circuit (connection-oriented) approach.

Datagram (Connectionless) Approach

• In the datagram approach, the network layer treats each packet independently.
• Packets in a message may or may not travel the same path to their destination.
• The router only routes the packet based on the destination address.

Virtual-Circuit (Connection-Oriented) Approach

• In the virtual-circuit approach, a virtual connection is set up to define the path for the packets.
• The packets in a message follow the same path to their destination.
• A virtual circuit identifier is used to define the virtual path the packet should follow.

Creating a Virtual-Circuit Connection

• Three phases are used to create a virtual circuit connection: setup phase, data-transfer phase, and teardown phase.
• In the setup phase, a request packet and an acknowledgment packet are exchanged between the source and the destination.
• In the data-transfer phase, the packets in a message are sent one after another.
• In the teardown phase, the source sends a teardown packet, and the destination responds with a confirmation packet.

DHCP and NAT

• DHCP (Dynamic Host Configuration Protocol) is an application-layer program that assigns IP addresses to hosts or routers.
• NAT (Network Address Translation) enables a user to have a large set of addresses internally and a small set of addresses externally.
• NAT helps to conserve IP addresses.