Establishing a Mesh Portal

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Creating a mesh portal was automatic in releases after 484, but it is currently disabled. Also note that the wireless frame format differs with earlier versions; new mesh versions cannot interoperate with old versions. This is to bring us closer to the still evolving and not yet finished 802.11s standard under development.

The preferred method for most testing is to let the XO create a mesh automatically, and to use an ethernet interface rather than via associating with a conventional access point.

New Mesh Portal installation

See Test Config Notes#Turn on MPP Capability.

Old Mesh Portal installation

Note: This page provides info on making the XO emulate a School Server MPP. From nand image 484+, if you connect an XO to an infrastructure access point, or connect it to a network via USB-Eth dongle, the XO will automatically create a mesh and provide link local addressing.

Requirements

• A USB ethernet adapter
• One OLPC laptop (XO)
• The xo-mpp-server RPM here: xo-mpp-server-0.1-1.noarch.rpm
• (The srpm is here, but you don't need it to setup the MPP)
• Note: The laptop that will serve as a Mesh Portal needs to run q2c18.rom (or greater), and nand image 484 (or greater).

What to do

• Boot up your XO

• Switch to a virtual terminal (press Ctrl+Alt+F1), and log in as 'root'

• Turn off NetworkManager and avahi

chkconfig --level 2345 NetworkManager off
chkconfig --level 2345 avahi-daemon off

• Set your init level to '3'; stopping Sugar and X from starting again.

nano /etc/inittab

find the line with:

id:5:initdefault:

and change the '5' to a '3' so it looks like this instead:

id:3:initdefault:

• Plug the USB ethernet adapter into the XO

• Reboot; type 'reboot' and press enter

• Wait for the XO to boot to the login prompt, then log in as 'root'

• Bring up the USB ethernet interface

ifup eth0

• Install the DHCP daemon

yum -y install dhcp

You may have to try this command twice; yum sometimes runs out of memory doing dependency solving, and terminates before actually installing the RPM. Keep trying until the last line says "completed!".

• Copy the xo-mpp-server RPM onto the XO and install it:

rpm -Uhv xo-mpp-server-0.1-1.noarch.rpm --force

• Turn on various services at startup

chkconfig --level 345 network on
chkconfig --level 345 iptables on
chkconfig --level 345 dhcpd on
chkconfig --level 345 mpp on

• Reboot; type 'reboot' and press enter

and it should all work

Using the wireless eth0 interface to connect to an access point

You can configure an all-wireless MPP to route between eth0 and msh0 on the same wireless radio. This will introduce another wireless hop with the subsequent reduction in throughput, however it will be the most common MPP configuration.

To do that you need to make sure that the msh0 interface gets initialized before the eth0 interface in /etc/init.d/network and that eth0 is associated with an Access Point and has a valid IP configuration before the mpp script starts.

Testing a larger network with multiple MPPs

The important thing to keep in mind here is that there can only be one DHCP server and that every MPP's msh0 interface needs a unique IP address.

If the xo-mpp-server RPM is installed, the /etc/sysconfig/network-scripts/ifcfg-msh0 needs to be edited to set the IP address for that interface. Also editing /etc/dhcpd.conf on the machine that runs the DHCP server (so that the MPP addresses won't be in the DHCP pool) is required.

Troubleshooting

Feel free to contribute your own troubleshooting tips here.

The laptops don't connect to the mesh portal!

• Build385 or higher is needed on the client laptops for these instructions.

Further Reading

More information is available on these topics:

• Mesh Portal discovery protocol
• How things work in Trial1
• Cozybit's MPP Utils