Network@home

wireless clients – HP, IBM, HTC devices
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| WPA-PSK (TKIP) – some older wifi devices will not connect using WPA2-PSK (AES), so TKIP for backward compatibility
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Netgear WPNT834 RangeMax* 240 wifi router (802.11g&b is enough) [192.168.111.0 network] – 3 antenna wifi router, older, but good and support RangeMax technology.
[Settings]
Mode: 802.11g&b is enough 54Mbit/s
Preamble: Long for backward compatibility with b mode devices (short increases throughput)
Fragmentation Threshold**: 2346
CTS/RTS Threshold: 2346
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| Cat5 100Mbit/s
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Linksys WRT54GS wifi router [192.168.11.0 network] – 2 antenna wifi router, very reliable, customized, (acquired by Cisco) Reference
[Settings]
Mode: 802.11g&b
Preamble: Long for backward compatibility with b mode devices (short increases throughput)
Fragmentation Threshold: 2346
CTS/RTS Threshold: 2346
Transmit power: 52mW
Wireless Multimedia extensions: Enabled
No ACK for WMM packets: Enabled
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| wireless WPA-PSK (TKIP) – besides Linksys does not support client mode in WPA2
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Sagemcom – Sky Broadband router (802.11g&b) [192.168.12.0 network] – this ADSL modem-router seems does not support WPA2, but Radius (WPA-802.1x).

So what I have here?
I have 3 broadcast domains and depending how many clients are connected from 3 to 10 collision domains (wired have collisions only in half duplex, full duplex uses different frequencies for sending and receiving, so no collisions).
2 broadcast domains also live on wireless transmission, so there are 2 broadcast domains that are vulnerable to collisions.
Every network have network mask set to 255.255.255.0, so it makes 254 hosts available on each.
There is DHCP service enabled on every router.

*

Explaining RangeMax™ Antennas

RangeMax equipment uses a number of antennas, while other products usually use one at a time.

The simplest antenna configuration is a single antenna which is used both to transmit and to receive. This configuration is used on most networking equipment. Antennas transmit and receive in a fixed pattern; in NETGEAR equipment often one that’s omni-directional (as you would see it from above, a circular donut shape), or one that’s more directional (a figure 8, or an oval shape radiating mostly in one direction).

Some non-RangeMax equipment has two antennas. In this configuration, for example with the WG302 access point, the antenna with the better signal is dynamically determined every few moments, and the other one is turned off.

MIMO technology and spacial multiplexing is much more complicated, because routers and access points use a number of antennas which transmit and receive at once. (Ethernet RangeMax adapters still use a single antenna, however.) This technology removes much of the guesswork in antenna placement by constantly assessing a number of ways of transmitting. This technology is so complex, in fact, that the IEEE standards committee — which is responsible for recommending standards to be used around the world — does not plan to finalize the 802.11n standard perhaps until 2007.

In the meantime, creative companies are developing technology which customers can have right now. Because the 802.11n standard is not finalized, it is not possible for any company to claim their current MIMO products will be compatible. There are now years of experience with MIMO technology without 802.11n, while the first generation of 802.11n has yet to be produced. Therefore the existing technology is likely to continue, even after 802.11n is finalized.
[from netgear.com]

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They’re mutually exclusive from each other. Fragment threshold is access-point centric (802.11), MTU is IP header based….. Difference between layer2 and layer3 in a nutshell.
Yes, fragment threshold can be above MTU, and MTU can be above fragment threshold.

Fragmentation threshold is between your access point and you. If your MTU is lower than your fragment threshold then YOU WILL NEVER see 802.11 fragments.

If your MTU is higher than your frag threshold, AND the payload is large enough then your access-point will force a fragment and the frame will be split up between host and AP to be reassembled upon delivery.

You generally want your MTU to be whatever the maximum MTU is of your AP/LAN/Internet connection. This is generally 1500 bytes, however in some cases where PPPOE/ATMOE/VPLSOE or other carrier-to-carrier encapsulation is used.

Why would you want fragmentation?

The only reason you would be interested in fragmentation is if your wireless network is in a noisy area (alot of other AP’s), you see ALOT of loss during an action such as a file transfer, and/or you have a large amount of workstations in your WIFI network.

The reason for this is fairly straightforward:
If your MTU is 1500 bytes and you’re receiving data over your wireless network and there’s a wireless collision caused by another transmitting station or otherwise, the entire frame is lost and the source station will have to retransmit it (i.e. no ACK received, retransmission) This greatly slows throughput if it happens often.

If your MTU is 1500 bytes, and you fragment threshold is 576 bytes [mere examples], then your AP will force fragments between itself and the wireless device. The payload from the AP is split into multiple 576 byte chunks (3 wireless frames), and are then subsequently reassmbled.

The reason this CAN speed things up, is in a wireless network where RTS/CTS aren’t used [this is really the recommended approach], a wireless workstation needs 34us to sense a channel, 16us RTS, data transmission of roughly 600us for full payload, 16us for ack, 34us for DIFS, and roughly another 9us for another slot time.

With a fragmented payload, the time-in flight for a full frame can be reduced, as well as the DIFS time. (i.e. -400us for payload, -34us for DIFS). This also allows other devices to essentially interleave their transmissions within available slots.
[author O111111O]

New home network:
Huawei EchoLife HG612 Home Gateway FTTC
Modem/Gateway/AP1: Technicolor TG582n
10.0.0.10 / WPA2

Router/AP2: Netgear DGN1000 Wireless-N
10.0.0.11 / WPA2
Basic Settings – disabled NAT and firewall – this changes the mode from gateway to router only
Advanced – Static Routes – static route setup to Technicolor, because there is no RIP in place

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whatever you do or fix please test it afterwards, better however do not fix things that work, wait until they break otherwise feel the wrath of dummy users.