Switching and VLANS

Question 1

Switching Loop

Answer 1

Switching or bridging loops occur when there is more than one 2 layer path

Broadcasts or multicasts sent out on the network and broadcast traffic is flooded out of all ports

Broadcast frames will repeat and flood the network continuously until the CPU and Bandwidth are completely consumed on the switches

Question 2

STP

Answer 2

Spanning Tree Protocol is a loop prevention protocol. 802.1D

Creates a loop-free ethernet topology amongst switches

Switches talk to each other and build a map of the tree

Switches block redundant ports between other switches which ensures there will be only one path and no loops

Runs on most modern switches by default

Question 3

BPDU

Answer 3

Switches communicate about STP using Bridge Protocol Data Unit.

Contains the switch MAC address and STP priority value (Bridge ID)

Switch elect the Spanning Tree Root Bridge using Bridge ID, determined by lowest # Bridge ID

Question 4

Root Bridge

Answer 4

Where all the other switches will lead back to, central location ideal.

If left as the default the Root Bridge will be the switch with the lowest MAC address

Question 5

802.1D

Answer 5

STP, Spanning Tree Protocol
is a loop prevention protocol. 802.1D

Creates a loop-free ethernet topology amongst switches

Switches talk to each other and build a map of the tree

Switches block redundant ports between other switches which ensures there will be only one path and no loops

Runs on most modern switches by default

Question 6

RSTP

Answer 6

Rapid Spanning Tree. 802.1W

Faster than classic spanning tree

RSTP has less port states and faster convergence

Question 7

MSTP

Answer 7

Multiple Spanning Tree Protocol

Question 8

PVST

Answer 8

Per-VLAN Spanning Tree

Question 9

SPB

Answer 9

Shortest Path Bridging is the most recent evolution of these Spanning Tree Protocols

Question 10

Switch Ports

Answer 10

Always have a speed and duplex setting
“Anything with a NIC has a speed and duplex setting”

Speed and Duplex must match between each connection, AKA full duplex or half duplex

Question 11

POE

Answer 11

Power over Ethernet. 802.3AF
Provides electrical power to POE capable devices of a CAT5 or better cable

Do not require a traditional powercord

POE+ is 802.3at and can provide up to 25.5 watts for type 2 devices

Question 12

802.1W

Answer 12

RSTP, Rapid Spanning Tree Protocol

Faster than classic spanning tree

RSTP has less port states and faster convergence

Question 13

802.3AF

Answer 13

POE
Provides electrical power to POE capable devices of a CAT5 or better cable

Do not require a traditional powercord

POE+ is 802.3at and can provide up to 25.5 watts for type 2 devices

Question 14

Port Bonding

Answer 14

Used with LACP (Link Aggregation Control Protocol) combines multiple switch ports into a single connection, bonded connections are seen and used by switches as a single link with increased bandwidth

Used on connections to upstream switches to prevent network congestion

Question 15

Port Mirroring

Answer 15

Used to monitor traffic of a specific port

Duplicates network traffic from one port and mirrors it to another port

Can be local port mirror or remote port mirror

Question 16

MAC Filtering

Answer 16

Whitelisted MAC addresses are allowed and Blacklisted MAC addresses are blocked on all ports

Question 17

Port Security

Answer 17

Allows a specific MAC address to connect to a specific port

If the wrong MAC address is detected the port gets automaticaly shut down

Question 18

Authentication

Answer 18

Switches can send network authentication requests to an authentication server for verification of the user account and/or host MAC address

802.1X provides an authentication mechanism in which user authentication can be communicated with the authentication server

The switch will first allow only 802.1X rlated data from the host, once authenticated the switch will allow the host to begin passing regular traffic on the network

Question 19

802.1X

Answer 19

Provides an authentication mechanism in which user authentication can be communicated with the authentication server

Question 20

QoS

Answer 20

Quality of Service. Allows engineers to prioritize specific traffic and guarantee bandwidth during times of congestion. Example, bandwidth for voice or video, data or internet

Required for VoIP to function optimally

Does this by using tags called COS (layer 2 tag) and DSCP (layer 3 tag)

Question 21

Link Aggregation

Answer 21

Port Bonding - uses the LACP for bonding ports

Question 22

COS

Answer 22

Class of Service: Layer 2 tag for QoS

Question 23

DSCP

Answer 23

Differentiated Services Code Point. Layer 3 tag for QoS

Question 24

VLAN

Answer 24

Virtual Local Area Network

Allows us to segment layer 2 and layer 3 on our network into multiple virtual networks (broadcast domains)

Location independent

Question 25

VLAN Trunk

Answer 25

Virtual Local Area Network Trunk

Needed to pass traffic for more than one VLAN from one switch to another switch or router

Question 26

VTP

Answer 26

VLAN Trunking Protocol

Helps us pass VLANs from one switch to another switch

The VLAN Database of the VTP server is shared with the VTP clients

Question 27

VTP Transparent Mode

Answer 27

Makes it so the VLAN does not participate in any of the VTP

Question 28

Inter-VLAN Routing w/ Layer 3

Answer 28

Allows us to route layer 3 traffic from one VLAN to another VLAN, otherwise the hosts in one VLAN can never talk to the hosts in other VLANS

Layer 2 switch cannot do what layer 3 switch can

Question 29

Inter-VLAN Routing w/ Router

Answer 29

Allows a router to route traffic between VLANS

To enable it configure a trunk between the switch and a router and configure the router sub-interfaces