Padding and alignment in mac80211

802.11 hardware adds padding on RX packets and removes padding on TX packets. Morever, mac80211, the generic Linux 802.11 software stack expects some alignments on RX packets. As such, software drivers need to deal with all those constraints to avoid spurious or missing bytes to show up.

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HT40 channels

802.11n standard has been ratified on September, 11th 2009 according to the IEEE website : http://standards.ieee.org/announcements/ieee802.11n_2009amendment_ratified.html. It is now time to go into the details. Today we are looking at the HT40 definition.
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Tags: 802.11n

Testing ath9k

In order to stay up to date with ath9k linux driver, I decided to test it on a laptop. I have used an AR5418 (MB72) miniPCI card for this test and wireless-testing kernel (v2.6.32-rc7-43014-g505f756). I wanted to use this card in order to monitor 802.11n networks. Here is the result.

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GRE Ethernet tunnel and MTU

After creating a GRE Ethernet tunnel, it seems important to understand how encapsulation affects MTU along with some common pitfalls when using GRE Ethernet tunnel in Linux.
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Using GRE Ethernet tunnel

GRE stands for Generic Routing Encapsulation and it is a standard protocol defined in [RFC2784] and [RFC1701]. So far it has been used mainly for building IPv4 tunnels over IPv4. In this article, we will show you how to use it for building Ethernet tunnels over IPv4 using “Transparent Ethernet Bridging”.
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Tags: gre

Using virtual Ethernet pair device

I have been wondering what was virtual Ethernet pair Linux driver and how to use it. In fact, the principle is quite simple. As soon as you have created a pair of Ethernet like devices, each packet send at one side is received at the other side. Here is a quick tutorial on using it.
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