gluon-radv-filterd

This package drops all incoming router advertisements except for the default router with the best metric according to B.A.T.M.A.N. advanced.

Note that advertisements originating from the node itself (for example via gluon-radvd) are not affected and considered at all.

Selected router

The router selection mechanism is independent from the batman-adv gateway mode. In contrast, the device originating the router advertisement could be any router or client connected to the mesh, as radv-filterd captures all router advertisements originating from it. All nodes announcing router advertisement with a default lifetime greater than 0 are being considered as candidates.

In case a router is not a batman-adv originator itself, its TQ is defined by the originator it is connected to. This lookup uses the batman-adv global translation table.

Initially the router is selected by choosing the candidate with the strongest TQ. When another candidate can provide a better TQ metric, that outperforms the currently selected router by X metric units, it will be picked as the new selected router. The hysteresis threshold is configurable and prevents excessive flapping of the gateway.

Local routers

Local routers (i.e. local internet gateways connected to some nodes) that are connected to the client interface via cable or WLAN instead of via the mesh (technically: appearing in the transtable_local) are taken into account with a fake TQ of 512, so that they are always preferred.

Be aware of problems if you plan to use local routers together with the gluon-ebtables-filter-ra-dhcp package. These router advertisements are filtered anyway and reach neither the node nor any other client. Therefore the use of local routers is not possible as long as the package gluon-radv-filterd is used.

respondd module

This package also contains a module for respondd that announces the currently selected router via the statistics.gateway6 property using its interface MAC address. Note that this is different from the statistics.gateway property, which contains the MAC address of the main B.A.T.M.A.N. adv slave interface of the selected IPv4 gateway.

site.conf

radv_filterd.thresholdoptional

• minimal difference in TQ value that another gateway has to be better than the currently chosen gateway to become the new chosen gateway

• defaults to 20

Example:

radv_filterd = {
  threshold = 20,
}