Ccna4 -Chapter 6

Front 1

Frequency

Back 1

is the rate at which current cycles occur (or waves per second)

Front 2

wavelength

Back 2

is the speed of propogration of the electromagetic signals divided by the frequency in cycles per second.

Front 3

downstream

Back 3

the direction of RF transmission from the source to the destination. this transmission is called the forward path.
Frequency range is 50 to 860MHz

Front 4

upstream

Back 4

the direction of the RF signal transmission from subscribers to the headend or the reverse path. The range is 5 to 42MHz.

Front 5

physical layer

Back 5

channel width for data signals
200kHz, 400kHz, 800kHz, 1.6mHz, 3.2MHz, 6.4MHz.

Front 6

Frequency

Back 6

is the rate at which current cycles occur (or waves per second)

Front 7

wavelength

Back 7

is the speed of propogration of the electromagetic signals divided by the frequency in cycles per second.

Front 8

downstream

Back 8

the direction of RF transmission from the source to the destination. this transmission is called the forward path.
Frequency range is 50 to 860MHz

Front 9

upstream

Back 9

the direction of the RF signal transmission from subscribers to the headend or the reverse path. The range is 5 to 42MHz.

Front 10

physical layer

Back 10

channel width for data signals
200kHz, 400kHz, 800kHz, 1.6mHz, 3.2MHz, 6.4MHz.

Front 11

FDMA

Back 11

frequency division multiple access divides access by frequency.

Front 12

ADSL

Back 12

provides higher downstream bandwidth than upstream

Front 13

SDSL

Back 13

provides equal bandwidth for both upstream and downstream.

Front 14

benefits of ADSL

Back 14

-provide data services along with POTS voice service
-provider splits the POTS channel from the ADSL modem using filters and splitters .

Front 15

separate ADSL from voice

Back 15

using microfilter or by using a splitter

Front 16

microfilter

Back 16

is a passive low-pass filter with two ends. The one connects to the telephone and the other connects to the telephone wall.

Front 17

spiltter

Back 17

separate DSL traffic from POTS.
It's a passive device. In the event of a power failure, the voice traffics goes to the CO of the carrier.

Front 18

wimax

Back 18

aimed at providing wireless data over long distances:
point to point links to full mobile cellular type access.
-Higher bandwidth than WiFi

Front 19

satellite connections

Back 19

- one way multicast
- one way teerrestrial return
- two way

Front 20

one way multicast

Back 20

used for IP multicast-based data, audio and video distribution. One way satellite based services can be pushed pages to local storage at end user sites by satellite internet.

Front 21

one wya terrestrial return

Back 21

traditional dialup access to send outbound data through a modem and receive downloads from the satellite.

Front 22

two way satellite internet

Back 22

sends data from remote sites via satellite to the hub which then sends the data to the internet.

Front 23

two way satellite internet technology

Back 23

uses IP multicasting.
sends data from one point to many points at the same time by sending data in a compressed format.

Front 24

VPN benefits

Back 24

-cost savings - use third party internet transport to connect remote offices and users ot the site.
-security- advanced encryption and authentication protocols
-scalabiltity - easy to add new uses.

Front 25

site to site VPN

Back 25

hosts send and receive TCP/IP traffic through a VPN gateway. The gateway is responsible for encapsulating and encrypting outbound traffic for all the traffic from a particular site and sending it through a VPN tunnel over the internet to a peer VPN gateway.

Front 26

charateristics of Secure VPNs

Back 26

-data confidentiality
(protecting the contents of the messages)
data integrity - guarantees that no tampering occurs to the data while it travels bet source and destination.
authentication - ensures the the message comes from the authentic source and goes to the authentic destination.

Front 27

tunnelling protocols

Back 27

carrier protocol - the protocol over which the information is travelling
encapsulating protocol - the protocol that's wrapped around the data
the passenger protocol - the protocol over which the original information was travelled.

Front 28

encapsulation process

Back 28

- PPP carries the message to the VPN device.
the message is encapsulated within a Generic Route Encapsulation packet.

Front 29

GRE

Back 29

an tunnelling protocol by Cisco that can encapsulate a wide variety of protocol packet types inside IP tunnels creating a virtual point-to-point link to cisco routers at remote pointe over an IP internetwork.

Front 30

DES

Back 30

data encryption standard algorithm - 56 bit key ensuring high performance encryption. DES is a symmetric key cryptosystem.

Front 31

3DES

Back 31

triple DES algorithm - encrypts with one key and decrypts with another and encrypts with again with another key.

Front 32

AES

Back 32

Advanced encryption standard - offers 3 different key lengths
128, 192, and 256.

Front 33

RSA

Back 33

Rivest, Shamir and Adleman
assymetrical key cryptosystem. Bit lengths of 512, 768, 1024 or larger.

Front 34

symmetrick encryption

Back 34

each computer encrypts the information before sending it over the network. Requires knowledge of which computer will be talking to each other so that they all have the same key.

Front 35

asymmetric encryption

Back 35

uses different keys for encryption and decryption
knowing one of the keys doesn't help to decode
public key encryption is a variant of this.
recepient gives a public key to the sender. The sender uses a private key combined with the recepients public key to encrypt the message. the sender must share the public key with the recepient. The recipient will use the public key of the sender with their own private key.

Front 36

IP Sec framework protocols

Back 36

- authentication Header (ah)
use when confidentiality is not required or permitted.
-provides data authentication and integrity
-does not provide encryption.

Front 37

IP sec framework protocol - 2

Back 37

Encapsulation Security Payload (ESP)
-provides confidentiality and authentication by encrypting the IP packet. ESP authenticates the ineer IP packet and the ESP header.