This document explains the main information about the Wi Fi technology, it's standards, features and main providers for Cable Modem Wi Fi

1. WI-FI
Wireless Fidelity - Basic Introduction
Rogelio Gomez
http://ar.linkedin.com/in/rogeliogomez

2. Index
• Standards
• Authentication
• Cable Modems with Wi-Fi

3. Standards
• IEEE 802.11a (5 GHz)
• IEEE 802.11b (2.4 GHz – 11 Mbps)
• IEEE 802.11g (2.4 GHz - 54 Mbps)
• 802.11g+ (100 Mbps)
• Can coexists with a and b
• IEEE 802.11n (2.4 GHz and 5 GHz - MIMO 600 Mbps)
• Also there are private vendors standards

4. 802.11a
• 12 non-overlapping channels – 8 for network 4 for point-
to-point
• No IOP with 802.11b
• 5 Ghz better performance than b/g
• 54 Mbps
802.11b
• 13 channel with overlapping
• 2.4 Ghz
• 11 Mbps

5. 802.11g
• Improves b to reach 54 Mbps
• The total (20 Mhz) 13 overlapping channels
• Back compatible with b in 2.4 Ghz
802.11n
• MIMO Multiple Input Multiple Output (major improvement)
• Channel Bonding to make 40 Mhz channel will have 9
channels available
• The total in 20 Mhz are 13 channels
• Newer and full compatible backwards

6. Configuration
• SSID
• Name up to 32 characters
• Disable Broadcast
• Multiple SSIDs configuration , when this happens we set a VLAN
for each SSID

7. Authentication
WEP (10c- 26c 64/128 bit static encryption RC4)
Open: This option doesn’t authenticate the user. It has the
following options:
• No Encryption: Doesn’t encrypt the communication.
• WEP Encryption: Specifies WEP encryption is used. We should select
where to store the WEP key
• Key Source:
• Local: The WEP key is stored in the device. Usually by default. If this option is selected
the key should be generated selecting the length, format and value
• Server: Indicates that the WEP key is dynamically generated by the RADIUS server.
• Both: The Key is stored locally and in the RADIUS Server.
• Auth Server: Indicates that the WEP key is stored in an authentication
server.
WEP Shared Key: The WEP key is pre shared in order to
authenticate the user before the communication starts
Auto: Specifies that both methods are accepted Open y Shared
Key.

8. Authentication
• WPA/WPA2/WPA
•
•
Vulnerability when activating WPS (Wi-Fi Protected Setup) and WPA
WPA2 supports CCMP encryption (AES – Advanced Encryption Standard)
• WPA/WPA2/WPA Auto Pre-Shared Key PSK: Allows to create a shared key that all clients will
store. With the options:
•
•
•
HEXA key: The key should be 256-bit (64 characters) in hexadecimal.
Key by password: The password must contain between 8-63 ASCII characters.
Rekey Interval: Sets the group key update interval, which can range from 30-4294967295 seconds. The default value is
1800 seconds. You can also specify 0 to disable key updates.
• Encryption Type: You can choose the following options:
•
•
•
TKIP: TKIP Temporary Key Integrity Protocol generates a key of 128 bit per package using RC4 with a new key per package
AES: Advanced Encryption Standard. Uses CCMP encryption.
Auto: Can select between AES or Temporal Key Integrity Protocol (TKIP) Usually this option uses AES at first if no connection
then it falls back to TKIP
• WPA/WPA2/WPA Authentication Server: Wi-Fi Protected Access (WPA) authentication with a
server. If you enable WPA, WPA2, or WPA authentication, you must also configure the
authentication server.
• After selecting an authentication method, enter authentication server information with the
following:
•
Rekey Interval: Sets the group key update interval, which can range from 30-4294967295 seconds. The default value is
1800 seconds. You can also specify 0 to disable key updates.
• Encryption Type: Specify the encryption method between the AP and the client:
•
•
•
Auto
TKIP
AES
• The Mixed WPA/WPA2 method usually tries with WPA2 if is not successful it falls back to
WPA. The standard for WPA2 is 802.11i (WPA has no standardization)

9. Cable Modems with Wi-Fi
• Cisco DPC2525
• Ubee
• Thomson DWG855
• Cisco DPC2420

10. Cisco DPC2525
• Wireless
• 802.11g con 4 SSIDs
• Wireless Multimedia (WIMM) including Wi-Fi Protected Setup by
button
• Dual Antenna
• Ethernet
• 4 ports
• Firewall
• Parental Control
• Voice
• Upgradeable to SIP
• Codecs G.711, T.38, G.729, BV16
• Codec Encryption AES-128
• Call Features Support (Caller ID, Call Waiting, Call Forwarding, Call
Transfer)
• 2 Voice Ports

11. Ubee
• Wireless
• SSID
• Security
• WPA2-PSK con AES recommended
• Wi-Fi Protected Setup (push button or PIN method)
• 802.11 Frequency 802.11b/g/n 2.4 GHz some support 5 GHz. Can select the
channels or just use AUTO
• RSSI Receive Signal Strength Indicator: Indicates the signal level for each
connected device
• Firewall
• DMZ
• Port Scan Detection
• Filter Cookies
• IP Flood attack
• Content Filter
• DHCP
• Port Forwarding

12. Thomson DWG855
• Voice
• 2 RJ11
• RAS & 56 bit encryption security
• V.90 fax
• Wireless
• SSID
• Name – Open - Close
•
•
•
•
•
Channel (11 channels - the TWG850 13 channels
Enable / Disable
Security (WPA/WPA2/WEP/802.1x Radius)
Access Control (MAC allow/restric)
Advanced (Proprietary Air Interface, Rate, Output Power, Beacon
interval)
• Bridging WDS (Wireless Distribution System) allows to interconnect
APs options: Enable/Disable/Remote Bridges MAC(up to 4)

13. Cisco DPC2420
• Voice
• 2 Ports
• Ethernet
• 1 Port
• Wireless
• Basic (up to 11 channels– SSID)
• Security (WEP/WPA/WPA2 - WPS)
• Advanced (data rates and thresholds)
• Access Control (filter by MAC, SSID broadcast, Open system o PSK)
• WDS Wireless Distribution System
• Parental Control
• User Setup (create users profile and apply access rules to those users)
• Basic Rules (create rules and block content information)
• Time of the Day Rules (block all traffic in certain time)
• Local Log
• Firewall
• Web Pages filtering
• Event Logging & email config for Alerts
• Basic Setting (Network config, time NTP, Mngmt IP, Network)
• Advanced Settings
• IP Address Filtering
• MAC Address Filtering
• Port Filtering
• Port Forwarding
• DDNS (Dynamic DNS – Requires previous subscription to a provider of DDNS – user password host)
• Port Triggers (deactivate port when no activity)
• DMZ Host (Set IP visibity from outside by passing the firewall)
• VPN Termination (configuration and protocol control and VPN tunnels)

14. THANKS!