[quagga-dev 8833] New feature idea- "LAN Sensing"- provide a useable route to a broken LAN

Daniel Ng daniel.ng1234 at gmail.com
Tue Sep 13 03:11:06 BST 2011


Say there are 2 Quagga Routers, each with an ethernet interface to a LAN.

Quagga Router A is connected to the LAN via a working switch.

However, Quagga Router B is connected to a broken switch on the LAN, such that
the connection to Router B is fine, but the connection between the switch and
the LAN is down. Hence the ethernet interface on Router B seems OK, but Router B
cannot reach the LAN via this interface.

The 2 Quagga Routers are also connected via a PPP link.

Can Quagga be somehow enhanced so that Router B would know to route traffic
destined for the LAN, via the PPP connection (rather than forward it out its LAN
interface)? After all, there is no point in forwarding such traffic out the LAN
interface it the traffic just gets stuck at the broken switch!

For example, say there is an OSPF speaker on the LAN, and OSPF is enabled on all
interfaces on the Quagga Routers. Only Router A would receive Hello Packets from
the OSPF speaker (via its LAN interface) because Router B is connected to the
broken switch. Using this knowledge, can Quagga be changed so that on Router B,
the route to the LAN via the PPP link is used, rather than the
directly-connected route?


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