wirelezz blog

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Posts Tagged ‘wireless

A Proximity-Aware Transparent Handoff Mobility Scheme for VoWMN (PATH)

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Last year, I dedicated an important part of my work and time at the research center of my University to develop a way to provide fast handoffs within a 802.11s network. This post briefly describes it, named PATH after several attempts to make it sound cool.

Related Work

Most of the inspiration came from a great and interesting project called SMesh, a fast handoff mobility system created by the DSN Labs staff at Johns Hopkins University. One of the people behind the system is @ralucam, who helped me to understand the protocols of this system.

Yet another work that was taken into consideration is LCMIM, which is a Light-weight Client Mobility approach for Infrastructure Mesh networks. It is basically a simpler solution than SMesh but it is somewhat inefficient as it continuosly contends for the medium by broadcasting gARP messages, flooding the channel even though no Client is really using the network and that is bound to be used with a reactive routing protocol, in the case presented in the paper, AODV. The good side is that its nodes maintain independence and that it’s a simpler solution as well.

The PATH scheme

After several months of hard work and going through a learning process, I developed PATH, a Proximity-Aware Transparent Handoff mobility scheme. I should state that it is by no means a solution as complex and complete as SMesh as it only addresses the reversed channel latency issues caused by handoffs, but it certainly is simpler to install, follows a simpler logic and is independent of the type of routing protocol used as well.

The paper that describes its procedures has been recently accepted in INTERCON 2011, in Peru, for publication. I’ve shared the presentation here:

It all went good. It basically sends gARP messages based on client proximity (which is measured by the perceived RSSI on each node), thus associating clients to new nodes and switching its connectivity. Take a read to the presentation!. It should be noted that all three: SMesh, LCMIM and PATH create an infrastructure Mesh Network by setting wireless nodes into adhoc mode. By using this mode, all three schemes do not let the client decide when to roam but leave the responsibility to the network nodes.

It was designed to provide fast handoffs for real-time voice applications. Although it is essentially a work in progress and there are lots of ways to improve the scheme, I had the opportunity to share the results and they were all great 🙂

I will be posting a link to the paper soon!. Hope you like the presentation.


Written by Wirelezz

August 14, 2011 at 11:00 am

Posted in etc

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TKIP and WEP: Game Over

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So the other day I read the following in WiFiNews:

TKIP and WEP won’t be allowed in new devices with the Wi-Fi stamp in a staged elimination over three years starting in 2011.

My first reaction was: “Why did it take so long?”. It is well known that WEP is one insecure standard for IEEE 802.11 Networks. I’m no security expert, but there’s something I’ve learned in the past 7 years from different sources of information: “Don’t implement WEP on your wireless network”.

According to the post, “While TKIP hasn’t been broken, it has known vulnerabilities, such as a susceptibility to dictionary-based attacks for short keys, and some very clever ways to insert packets through manipulating a flaw in the packet integrity protocol.”.

However, it looks like it’s going to take some time to be accomplished:

At the start of 2011, access points will no longer be certified with TKIP as an option by itself, commonly revealed as WPA-PSK, WPA-TKIP, or WPA Personal. Mixed modes, in which an AP can accept either TKIP or AES keys, will still be allowed. But also starting in 2011, manufacturers can opt to ship Wi-Fi hardware preset to use WPA2 out of the box.

In 2012, new Wi-Fi adapters (so-called stations in 802.11 parlance) won’t be allowed to support TKIP.

In 2013, WEP is finally disallowed for APs. While that seems incredibly late, its inclusion is there only for certain categories of legacy devices for which no other option is available.

In 2014, the mixed TKIP/AES mode for access points can no longer be included in certified devices, and WEP cannot be available to new client devices.

As you may also know, 802.11n implements 802.11i security and gives TKIP support for those non-AES devices (however, 802.11n with TKIP won’t support data rates higher than 54Mbps).

While I think this should have been done severals years ago and that security standards should walk together with 802.11 innovations (such as 802.11n), I’m also interested in finding out how to meet the point in which new security schemes will not affect 802.11 handoffs as more handshakes and protocols are added in the process.

Source: WiFiNews

Written by Wirelezz

June 27, 2010 at 3:50 pm

Posted in News

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