Lesson 8: Explaining Network Topologies and Types

Question 1

Define a client-server network

Answer 1

A network where its nodes are made up of PCs, laptops, and servers

Question 2

Define a peer-to-peer network

Answer 2

A network where an end system acts as both client and server, typically in a residential network

Question 3

Define a star topology

Answer 3

Endpoint nodes are connected to a central forwarding node, such as a hub, switch, or router. The central node mediates communications between the endpoints

Question 4

Define a mesh topology

Answer 4

Each device has (in theory) a point-to-point connection with every other device to create redundant routes

Question 5

What is the equation to determine how many links are needed in a mesh network

Answer 5

Let n represent the number of nodes planned to be in the network: n (n-1)/2

Question 6

Define a ring topology

Answer 6

A topology where each node has a point to point connection with each of its neighbors in the logical ring, each node will receive a transmission and continue to forward it until the transmission has reached its destination

Question 7

Define a bus topology

Answer 7

A logical bus topology is one in which nodes are attached to the single cable and receive the data transmitted all at the same time, regardless of the physical wiring layout of the network

Question 8

Define a Personal Area Network

Answer 8

The concept of IOT such as phones, laptops, printers, smart watches to connect to each other

Question 9

Define the three tiered network hierarchy

Answer 9

Paradigm to simplify network design by separating switch and router functionality with a separate role and topology

Question 10

What three tiers make up a three-tiered network hierarchy?

Answer 10

1. Access/Edge layer
2. Distribution/Aggregation layer
3. Core layer

Question 11

Define the Access layer

Answer 11

Bottom tier of the hierarchy that allows end-user devices to connect to the network through wired/wireless access and LAN switches

Question 12

Define the Distribution/Aggregation layer

Answer 12

Intermediate tier that provides fault-tolerant interconnections between the access layer and the core layer using layer 3 capable switches with 10GB for switching and 40GB ports for routing

Question 13

What technology does a layer 3 switch use?

Answer 13

Application Specific Integrated Circuit (ASIC)

Question 14

Define the Core layer

Answer 14

Highest tier in three-tiered network hierarchy that uses routers and layer 3 switches configured in a mesh topology to provide redundant paths for data to flow around the access and distribution layers

Question 15

What layer 2 protocol is used to prevent network loops?

Answer 15

Spanning tree protocol (STP)

Question 16

Define a spanning tree protocol hierarchy

Answer 16

The root bridge is the switch at the top of the hierarchy and is selected based on the lowest ID and is connected to the remaining bridges

Question 17

How do switches in a spanning tree hierarchy communicate?

Answer 17

Using data packaged as bridge protocol data unit (BPDU) in multicast frames

Question 18

Once configured, how does data flow between switches using spanning tree protocol (STP)?

Answer 18

The root bridge has two designated ports (DP) connected to lower tiered bridges. The lower tiered bridges have root ports (RP) connected back to the designated ports on the root bridge. The lower tiered bridges also have a connection directly to one another. One of the bridges in the lower tier must have a blocked port (BP) to prevent a loop

Question 19

How is spanning tree protocol configured on the switch?

Answer 19

If the switch supports STP it will operate by default, but and administrator should set priority value to define the root switch

Question 20

List the states a port can be in when the switch is using spanning tree protocol

Answer 20

1. Blocking - can’t forward or learn MACs
2. Listening - can’t forward or learn MACs but listens for BPDUs to detect loops
3. Learning - only listens for MACs to build MAC table and hierarchy
4. Forwarding - Preforms forwarding and learning
5. Disabled

Question 21

Described what it takes for spanning tree protocol network to be converged

Answer 21

All ports on all the switches are in forwarding or blocking states

Question 22

What is a switching flood

Answer 22

An issue where layer 2 broadcast messages (ARP, DHCP) circulate the network perpetually, which causes the switches to clear MAC address tables and start flooding unicast traffic

Question 23

Left unmanaged, what are the consequences of a switching flood?

Answer 23

A broadcast storm will occur, causing network latency and crashing switches

Question 24

Which two network models/topologies are used in a three-tier hierarchical model?

Answer 24

Core layer is mesh as well as the links between the core and distribution layer while the access layer uses a star topology to connect end systems

Question 25

What is the link used to connect two switches to each other?

Answer 25

Backbone link/Trunk

Question 26

How do trunked switches determine where to forward frames?

Answer 26

The VLAN ID (VID) of each frame is stored in the 802.1Q tag in an ethernet frame

Question 27

What is an untagged port?

Answer 27

Designation configured for ports that are connected to an end system

Question 28

What is a tagged/trunked port?

Answer 28

Designation configured for ports that are connected to another switch operating as a trunk

Question 29

What are the two ways a switch processes a VLAN tag

Answer 29

1. If a frame is addressed to a port in the same VLAN, no tag is added to the frame
2. If the frame needs to be transported over the trunk link, the switch adds the relevant 802.1Q tag to identify the VLAN