IP addressing + XO MPP connectivity

Daniel Drake dsd at laptop.org
Tue Jul 7 07:44:10 EDT 2009

Hi John,

On Tue, 2009-07-07 at 02:03 -0400, John Watlington wrote:
>    If you are getting a self-assigned IP address, it is
> because the laptop is not discovering the MPP.
> This is probably due to a short cut in the MPP
> discovery process.

The NM-0.6 code *definitely* ignores the IP address assigned from the
MPP DHCP server.

some snippets

	case MESH_S3_XO_MPP:
	/* Kill dhclient; we don't need it anymore after MPP discovery here
	 * because we're ignoring the returned lease.
	  nm_dhcp_manager_cancel_transaction (dhcp_manager,
	     nm_device_get_iface (NM_DEVICE (self)));


	if (self->priv->step == MESH_S3_XO_MPP) {
		/* Step 3 (XO_MPP) ignores the IP address provided in the DHCP response,
		 * so we still have to do autoip.
		if (!aipd_exec (self)) {
			nm_warning ("Activation (%s/mesh): couldn't start avahi-autoipd.",

> The XS server software should set up any mesh interfaces
> to accept the anycast MAC address, but this might have
> been lost in more recent builds. 

The XS connectivity scenario is a totally different case, where the DHCP
lease is indeed received and applied. The code differentiates between
"school mesh" and "mesh portal" (and the anycast addresses are

However I think you have indirectly explained why the MPP lease is
ignored... you are accounting for the case where there are multiple MPPs
all on 1 channel, therefore two MPPs could give the same IP address to 2
different XOs. autoipd presumably has some magic to avoid IP conflicts.

And this is a pain to implement so it will probably not happen this time
around... but I should be able to keep the school mesh case.


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