Transcript Home network customization

Home Network Customization
Willis Kim
Terminology
• Overview
• A broadband router combines the features of a traditional
network switch, a firewall, and a DHCP server. Broadband
routers are designed for convenience in setting up home
networks, particularly for homes with high-speed cable
modem or DSL Internet service. Broadband routers support
file sharing, Internet connection sharing, and home LAN
gaming. Broadband routers follow the Ethernet standard for
home networking. Traditional broadband routers required
Ethernet cables be run between the router, the broadband
modem, and each computer on the home LAN.
• Switch - A network switch is a small device that joins
multiple computers together at a low-level network
protocol layer. Technically, network switches operate at
layer two (Data Link Layer) of the OSI model.
Connectivity
Router Port
(DSL Port)
Switch Ports
802.11b is a WLAN communication
standard. 802.11b is one of the
wireless Ethernet standards in the
802.11 series. Its relatively low cost
naturally resulted in many home and
small business networks adopting
802.11b. 802.11b LANs support a
maximum data rate of 11 Mbps.
802.11g extends and improves
on the earlier 802.11b standard.
802.11g supports a maximum
bandwidth of 54 Mbps compared
to the 11 Mbps of 802.11b. To
achieve backward compatibility,
802.11g uses the same
communication frequency range
- 2.4 Ghz - as 802.11b.
Linksys (WRT54G) transmits 28mW or 14.5dBm with
a 2.2dBi omni directional antenna
Power
• Transmit Power
– Power (in dBm) = 10 * log10 (Signal/1mW)
• Radiated Power
– Antennas are passive devices that radiate radio frequency
energy (RF). They do not create RF energy, but focus the
energy in a specific area or direction, which increases the signal
strength in that area or direction. Antenna gain is measured in:
dBi relative to an isotropic radiator
• Total Power = Transmit + Radiated
– Effective Isotropic Radiated Power (EIRP) measured in dBm =
power at antenna input [dBm] + relative antenna gain [dBi]
Distance and Data Rate
Tools
• Free
– Built-in tools and utilities
– NetStumbler
– Ethereal
• Not free
– Network General Sniffer Portable
Why customize?
Increase signal strength
– Using software (only on certain devices)
– Using antenna
• Reduce noise
– Using Japan channel standard (rest of the
world)
Using software
• HyperWRT for Linksys WRT54G
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Adjustable Transmit Power (from 13 to 19 dBm)
Antenna Select
13 Wireless Channels
'Boot Wait' flash protection
More Port Forwarding & Triggering Fields
More QoS Device & Application Fields
Command Shell
Startup & Firewall Scripts
• Use at your own risk
– Use web interface to load software (load with cable links)
Using software (con’t)
• Demonstration
– Version information in top right hand corner
of initial page
– Optimal settings
• 16dBm (Linksys original firmware set to 14.5dBm)
• G-Only
Using antennas
• Linksys antenna is omni-directional with
2.2 dBi - 360°
Example omni-directional
Antenna (Horizontal Direction)
Example omni-directional
Antenna (Vertical Direction)
Using antennas (con’t)
• Panel antenna
– High Gain 6dBi Directional Wireless Antenna
with TNC connector - 80 ° (demonstration)
Example Panel Antenna
(Horizontal Direction)
Example Panel Antenna
(Vertical Direction)
Antenna Demonstration
Using antennas (con’t)
• Homemade reflector antenna
Reduce noise (interference)
• Interference – Operating on the same
frequency
• Operating Channels
– 802.11b/g:
• Channels 1-11 for Americas, Taiwan, Thailand
– Out of the box
• Channels 1-13 for rest of the World
– Reduces interface
– Needs custom firmware and rest of the world WLAN
drivers
Make sure you wireless NIC will
support channels 1-13
Non-technical solutions
• Move Access Point into center of house
• Try to avoid wall between access point
and client
• Wi-Fi is basically a three-wall device
Bonus – make your AP into a client
• Motivation - $80 for Linksys WRT54G router and
•
$60 for Wireless g NIC
Sveasoft for Linksys WRT54G
– Wireless
• Power mode selection
• Antenna selection
• Client mode (Ethernet bridging)
• Adhoc mode
– Advanced Routing
• OSPF, BGP Routing
– Use at your own risk
Bonus
• Linksys firmware is based on Linux
– HyperWRT command shell (demonstration)
• For example, ps, /sbin/ifconfig –a, cat
/tmp/udhcpd.conf
• WEP or not to WEP
– Prevent eavesdropping (demonstration)
– Increases configuration complexity
Example Topology
Subnet 255.255.255.0
VDSL via POTS
VDSL modem
Bridge and Wireless Access Point 802.11b
192.168.1.11
Channel 11 – 2.462 GHz
SSID2
Router and Wireless Access Point 802.11b/g
192.168.1.1 (gateway)
Channel 13 – 2.472 GHz
Wireless Bridge 802.11g
192.168.1.50
SSID1
`
Computer, DHCP
SSID1
Wireless Bridge 802.11b
192.168.1.225
SSID1
`
Fixed, 192.168.100.201
Computer
Fixed, 192.168.1.200
SSID2
Backup
DSL Type
Max. Send
Speed
Max.
Receive
Speed
Max.
Distance
Lines
Required
Phone
Support
ADSL
800 Kbps
8 Mbps
18,000 ft
(5,500 m)
1
Yes
HDSL
1.54 Mbps
1.54 Mbps
12,000 ft
(3,650 m)
2
No
VDSL
16 Mbps
52 Mbps
4,000 ft
(1,200 m)
1
Yes