Ethernet Fundamentals Flashcards

1
Q

Ethernet Fundamentals Overview

A

Please refer to study guide for info/diagrams

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2
Q

CSMA/CD

A

Carrier Sense Multiple Access/Collision Detect

Carrier Sense: Listen to the wire, verify it’s not busy
Multiple Access: All devices have access at any time

Collision Detect: If two devices transmit at same time, a collision occurs.
Back off, wait random time, try again

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3
Q

Collision Domains

A

Comprised of all devices on a shared Ethernet segment (same cable or hub)

Devices operate at half-duplex when connected to a hub

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4
Q

Collision Domains with Switches

A

Ethernet switches increase scalability of the network by creating multiple collision domains.

Each port on a switch is a collision domain (no chance of collisions), increases speed

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5
Q

Hub

A

Layer 1 device “Multiport repeaters”

Passive Hub: Repeats signal (no amplification)
Active Hub: Repeats signal with amplification
Smart Hub: Active hub with enhanced features (SNMP)

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6
Q

Bridges

A

Analyze source MAC address in frames entering the bridge & populate an internal MAC address table.

Make intelligent forwarding decisions based on destination MAC address in the frames.

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7
Q

Switch

A

Layer 2 device (Connects multiple network segments)
Essentially a multiport bridge

Learn MAC addresses & make forwarding decisions based on them.

Analyze source MAC in frames entering the switch & populate internal MAC table based on them.

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8
Q

Router

A

Layer 3 device (Connects multiple networks together)
Makes forwarding decisions based on IP addresses

More feature-rich & support broader range of interface types than multilayer switches

Each port is a separate collision/broadcast domain.

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9
Q

Layer 3 Switch

A

Layer 3 device (Connects multiple network segments)

Can make layer 3 routing decisions & interconnect entire networks (like a router)

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10
Q

Link Aggregation

A

802.3ad
Congestion can occur when ports all operate at same speed

Allows for combo of multiple physical connections into a single logical connection

Bandwidth available is increased & congestion minimized/prevented.

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11
Q

PoE

A

Power Over Ethernet (802.3af)
Supplies electrical power over Ethernet
Requires CAT5+
Up to 15.4 watts of power to device

PoE+ (802.3at)
Up to 25.5 watts of power to device

Device Types:
PSE (Power Sourcing Equipment)
PD (Powered Device)

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12
Q

Port Monitoring/Mirroring

A

Helpful to analyze packet flow over network
Network sniffers can see all traffic on a hub
Switches require port monitoring to see all traffic

Port mirroring makes a copy of all traffic destined for a port & sends it to another port

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13
Q

User Authentication

A

802.1x
For security purposes, switches can require users to authenticate themselves before gaining network access

Once authenticated, a key is generated & shared between the supplicant and the switch/authenticator

Auth server checks supplicant’s credentials & creates the key
Key is used to encrypt the traffic to/from the client

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14
Q

Management Access & Authentication

A

SSH: Remote admin program that allows you to connect to the switch over the network

Console Port: Allows for local admin of the switch using a separate laptop & a rollover cable (DB-9 to RJ-45)

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15
Q

OOB

A

Out-of-Band Management:

Involves keeping all network config devices on a separate network

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16
Q

First-Hop Redundancy

A

HSRP (Hot Standby Router Protocol) uses a virtual IP & MAC to provide an “active” & “standby” router
Cisco proprietary protocol

If active is offline, standby answers

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17
Q

Other First-Hop Redundancy Protocols

A

GLBP (Gateway Load Balancing Protocol)
Cisco proprietary protocol

VRRP (Virtual Router Redundancy Protocol)
Open-source

CARP (Common Address Redundancy Protocol)
Open-source

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18
Q

STP (Protocol)

A

Spanning Tree Protocol (802.1D)
Permits redundant links between switches & prevents looping of network traffic

SPB (Shortest Path Bridging) is used for larger network environments

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19
Q

Broadcast Storms

A

If broadcast frame received by both switches, they can forward frame to each other

Multiple copies of frame are forwarded, replicated, & forwarded again until the network is consumed with forwarding many copies of the same initial frame

20
Q

Root Bridge

A

Switch elected to act as a reference point for a spanning tree

Switch with lowest bridge ID (BID) is elected as root bridge.

BID is made up of a priority value & MAC (lowest value considered the root)

21
Q

Nonroot Bridge

A

All other switches in an STP topology

22
Q

Root Port

A

Every non-root bridge has a single root port
Port closest to the root bridge in terms of cost
If costs are equal, lowest port number is chosen

23
Q

Designated Port

A

Every network segment has a designated port
Port closest to the root bridge in terms of cost
All ports on root bridge are designated ports

24
Q

Non-Designated Port

A

Ports that block traffic to create loop-free topology

25
Q

Root & Nonroot Bridges

A

Single root port on non-root bridge
All other ports on non-root bridge are non-designated
All ports on root bridge are designated

26
Q

Port States

A

Non-designated ports do not forward traffic during normal operation (but receive BPDUs)

If a link in the topology goes down, the non-designated port detects the failure & determines whether it needs to transition to a forwarding state

To get to the forwarding state, it has to transition through four states

27
Q

The 4 Port States

A

Blocking:
BPDUs are received but not forwarded
Used at beginning and on redundant links

Listening:
Populates MAC table
Does not forward frames

Learning:
Processes BPDUs
Switch determines its role in the spanning tree

Forwarding:
Forwards frames for operations

Root & Non-designated ports are blocking
Designated ports are forwarding

28
Q

Link Costs

A
Associated with the speed of a link
10Mbps = 100
100Mbps = 19
1Gbps = 4
10Gbps = 2

Long STP is being adopted due to higher link speeds
Values range from 2,000,000 for 10Mbps to as little as 2 for 10Tbps

29
Q

VLAN

A

Virtual Local Area Network
Switch ports are in a single broadcast domain
Allows you to break out certain ports to be in different broadcast domains

Allows different logical networks to share the same physical hardware
Provides added security & efficiency

30
Q

VLAN Trunking

Also Identifier

A

(802.1q)
Multiple VLANs transmitted over the same physical cable

VLANs are tagged with 4-byte identifier:
TPI (Tag Protocol Identifier)
TCI (Tag Control Identifier)

One VLAN is left untagged (Native VLAN/VLAN0)

31
Q

VPN Concentrator

A

VPNs create a secure, virtual tunnel network over an untrusted network (like the internet)

Concentrators can terminate VPN tunnels (firewalls can do this too)

32
Q

NGFW

A

Next-Generation Firewall:
Conducts deep packet inspection at layer 7
Detects & prevents attacks
Much more powerful than basic stateless/stateful firewalls
Continually connects to cloud resources for latest info on threats

33
Q

IDS/IPS

A

Intrusion Detection System (IDS):
Recognizes attacks via signatures & anomalies

Intrusion Prevention System (IPS):
Recognizes & responds

Host or network-based devices

34
Q

DNS

A

Domain Name System:
Converts domain names to IP addresses
Similar to a phone contact list

35
Q

FQDN

A

Fully-Qualified Domain Name:

Domain name under a Top-Level Domain & represents a web, mail, or file server (.com, .net, .mil, .edu)

36
Q

URL

A

Uniform Resource Locator:
Contains the FQDN with method of accessing info

Example: https://www.diontraining.com

37
Q

Proxy Server

A

Device that makes a request to external network on behalf of a client.
Used for security to perform content filtering/logging

Workstation clients are configured to forward their packets to a proxy server

38
Q

Content Engine

A

AKA: “Caching Engines”
Dedicated appliances that perform the caching functions of a proxy server

More efficient than a proxy server

39
Q

Content Switches

A

AKA: “Load Balancers”
Distributes incoming requests across the various servers in the server farm

Useful for large companies like Amazon

40
Q

Deterministic Network

A

Organized & orderly
Need an electronic token to transmit
Ex: Token ring networks

41
Q

Contention-Based

A

Very chaotic
Transmit (almost) whenever you want
Ex: Ethernet networks

42
Q

Distance Limitations - Copper

Media, Bandwidth, Distance

A
10BASE-T (Cat3) = 100m
100BASE-TX (Cat5) = 100m
1000BASE-T (Cat5e) = 100m
1000BASE-T/10GBASE-T (Cat6) = 1/10Gbps = 100m/55m
10GBASE-T (Cat6a) = 100m
10GBASE-T (Cat7) = 100m
40GBASE-T (Cat8) = 30m
43
Q

Distance Limitations - Fiber

Media, Bandwidth, Distance

A
100BASE-FX (MMF) = 2km
100BASE-SX (MMF) = 300m
1000BASE-SX (MMF) = 220-550m
1000BASE-LX (SMF/MMF) = 5km/550m
10GBASE-SR (MMF) = 400m
10GBASE-LR (SMF) = 10km

S is NOT single!

44
Q

VPN Headend

A

A specific type of VPN concentrator used to terminate IPsec VPN tunnels within a router or other device.

45
Q

Unified Communications (or Call) Manager

A

Used to perform the call processing for hardware & software-based IP phones.

46
Q

ICS

A

Industrial Control System:

Describes the different types of control systems & associated instrumentation.

47
Q

SCADA

A

Supervisory Control & Data Acquisition:

Acquires & transmits data from different systems to a central panel for monitoring & control.