Chapter 5

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Study Notes

Network Layer Overview

The data plane operates locally on routers to forward incoming datagrams to the correct output ports.
The control plane employs network-wide logic, determining the routing of datagrams from the source to the destination, using traditional algorithms and Software-Defined Networking (SDN) approaches.

What’s Inside a Router

Input ports manage incoming data, perform link layer processing, and handle queuing of packets.
Switching components transfer datagrams from input to output ports using forwarding tables.
Output ports control outgoing data, queuing, and scheduling mechanisms for efficient packet transmission.

IP: The Internet Protocol

Datagram format defines the structure of data packets for transmission.
Addressing identifies devices on the network, essential for communication.
Network Address Translation (NAT) alters IP addresses in packet headers to enable routing through private and public networks.
IPv6 introduces a larger address space, accommodating an increasing number of devices on the internet.

Generalized Forwarding and SDN

Match+Action is a forwarding model where packet processing actions are based on the match of packet header fields.
OpenFlow is a key protocol in SDN, supporting the match+action forwarding principle.

Middleboxes

Middleboxes are additional network devices that offer various services beyond routing, such as firewalls, load balancers, and proxies.

Network Layer Functions

Forwarding refers to directing packets from an input link to the appropriate output link based on routing decisions.
Routing involves determining the best pathway for packets to travel from source to destination.

Switching Fabrics

Types of switching fabrics include Memory, Bus, and Interconnection Network, each affecting data transfer efficiency.
The switching rate indicates how rapidly packets are forwarded from inputs to outputs within a router.

Buffer Management

Buffering is necessary when datagrams arrive at a rate exceeding the link's transmission capacity to prevent data loss.
Drop policies like tail drop dictate which datagrams are discarded when buffers reach capacity.
Marking techniques signal congestion levels using methods like Explicit Congestion Notification (ECN) and Random Early Detection (RED).

Packet Scheduling

First-Come, First-Served (FCFS) processes packets based on their order of arrival.
Priority scheduling allows packets to be sent based on predefined priority levels.
Round Robin (RR) cycling method sends packets equally across classes in a rotating manner.
Weighted Fair Queueing (WFQ) delivers service based on different traffic class weights, ensuring fair distribution of bandwidth.

Network Service Models

Best Effort service model provides no guarantees regarding packet delivery, timing, or bandwidth availability.
Integrated Services (Intserv) model offers specific delivery guarantees for timing and bandwidth.
Differentiated Services (Diffserv) establishes various levels of service quality to meet different network needs.

Description

Test your knowledge on the Network Layer operations and the Internet Protocol (IP). This quiz covers the data and control planes, the inner workings of routers, and the essential features of datagrams and addressing. Enhance your understanding of how data is processed and routed in networks.