Flashing nights


Nada me dá mais prazer do que flashar estas belezas (Fonera Atheros SoC AR2315 18 dBi) com OpenWRT não FON. O que temos nesta caixita:

Architecture: MIPS 4KEc
Bootloader: RedBoot
System-On-Chip: Atheros AR2315
CPU Speed: 183 MHz
Flash size: 8 MiB
RAM: 16 MiB
Wireless: Integrated Atheros 802.11b/g
Ethernet: 1x RJ45
Serial: Yes

* 5V power supply
* Antenna
* SPI-Bus

A única coisa que sinto a falta: PoE. Para os que dão valor a throughput, o máximo que consegui entre um cliente WLAN e um FTP server ligado via WAN da Fonera foi cerca de 18Mbits, notando-se logo o load average num top. Túneis OpenVPN também portam-se bem, desde que não abusem da compressão LZO mas só testei 1 túnel. Quanto ao espaço de apenas 8M na Flash, o jffs2 ou squashfs permitem maravilhas. De qualquer modo, é uma questão de se dar mais prioridade a alguns ipkg (beware of tcpdump). Uma das coisa porreiras do OpenWRT 2.6 Atheros Kamikaze é que já vem com o madwifi com suporte para Minstrel a nível de rate control. Quem usa Adhoc em madwifi sabe bem a dor do sample rate control e performance em links menos ideiais.

Meraki: Free the Net SF

The Free the Net San Francisco is the biggest implementation of a Meraki Mesh in a city neighborhood so far. Meraki teamed up with the local communities to setup and give away the hardware (with some local agreements with DSL providers, for the internet backhaul) and mesh know-how. So, since they’ve announced the new network I’ve been following it. It has grown very quickly for the past 2 months, over 3000 people signed up but if you look closer on the Overview Map, there’s very few nodes that are actually linked to the others, to form a so-called Mesh Network. What I see is a hotspot network on S. Francisco, not a Mesh. So, for the reality check, you’ll need a lot more 60 mW nodes (not indoor ones) and big antennas to effectively start a metro-like Mesh Network. If Fon wanted to easily compete with Meraki, it just needed to take OLSR-ng, pay some development/code patches from the guys of Freifunk/B.A.T.M.A.N. and kill Meraki completely.

Meraki and a few impressions


I’ve been working on a Wifi Mesh experiment with Meraki Gear for the last 2 months. I was looking for a better low-cost single radio mesh alternative to the OLSR/OpenWRT platform (Freifunk Firmware). So far, the experiment is going well, it has some glitches with coverage due to the low-power radios of the Meraki Mini (60 mw), but at the end, the network really works and it has some advantages over Ad-hoc madness behavior on the standard atheros/linux code. Since last month I have 4 Meraki Minis on a 4 floor apartment complex, one per floor and the gateway linked to a wireless 802.11a p2p backhaul, through the ethernet interface. The overall user experience is good, but unfortunately, since it’s a closed box you can’t modify it to integrate with your current network. Yes, it runs Linux, you can login through ssh and you have the Meraki/OpenWRT modified source available. But the SrcRR protocol Click driver is not and all the network ip address scheme is hard coded (it’s calculated from the Mac Address). The clients get an adddress from the and the Mesh assigns a network. Also, one of the major problems for customization is that every node has NAT configured for every client, even for intra-mesh traffic. So, a client who’s connected to node A, can’t access directly a client on node B, because all the traffic from clients is NATed from every Mini. So, you have NAT on the Gateway node connected to the internet and for every other node on the Mesh. So if you have for example a wifi camera that’s not NAT friendly, be prepared for dealing with major headaches. There’s always a way to hack the Merakis, you can install an ipkg package from OpenWRT with your software or scripts, but you only have a /storage writable partion and from time to time there’s an on-the-air firmware upgrade that you don’t know what will do. So you’ll end up playing the catch & run game. The last option for total control is to flash the Meraki with a brand new OpenWRT. But for what? The most valuable piece of software it’s the SrcRR Mesh driver and you can’t get that with a plain OpenWRT and there’s always a cheaper alternative (at least, in Europe), the Foneras.
Oh and by the way, there’s no WPA or WPA2, just plain old WEP. I checked the Merakis and saw hostapd.conf on /etc, so they’re planning in the future to implement WPA.

But if what you want is a low-cost, plug&play mesh solution for your house or neighborhood with a great dashboard control, some statistics and a simple splash page to authenticate your users, Meraki rox. Oh and by the way, if you’re living in Europe, you’ll run a bit of trouble to get this babies from euro-resellers if you want to avoid customs. If you’re desperate, drop me a note.

Mesh on the OLPC

If you’re into Wifi Mesh Protocols there’s interesting news on the OLPC front and MIT work. They’re developing a new protocol based on a “probalistic presence mechanism” right into the OLPC firmware.

Polychronis Ypodimatopoulos, Pol for short, has developed a “probabilistic presence mechanism” in the mesh firmware for the OLPC. The presence mechanism uses a very small amount of information from packet headers to detect the presence of other nodes in the network (the ad-hoc meshing firmware in the OLPC relays packets without touching the kernel – a novel development in its own right). The other notable feature is that the time to detection is a linear function of the distance – a major change from most mesh networks where the routing table is either pre-determined or time to discovery is an exponential function of the distance.

And someone told me that it runs on Python too, userland, not a kernel module thing.