On 06/20/2018 09:18 AM, Grant Taylor wrote:
Where can I find more information on ignore_routes_with_linkdown? I don't see it listed in $Kernel/Documentation/networking/ip-sysctl.txt. (I do see fib_multipath_use_neigh documented there in.)
I'm specifically interested in if ignore_routes_with_linkdown and / or fib_multipath_use_neigh will cause Linux to fall back to an alternate (higher metric) route if the link is still up but the neighbor is not accessible across it.
+-------+
| Linux |
+---+---+
|
+-----+ +---+----+ +-----+
| R 1 +---+ Switch +---+ R 2 |
+-----+ +--------+ +-----+
A typical scenario is where Linux is connected to a DSL or Cable modem
where the physical link stays up even if the neighbor R {1,2} goes
offline. It's not possible to rely on the local link (MII) status to
determine that a neighbor is not reachable. I.e. R 1 going away like below.
+-------+
| Linux |
+---+---+
|
+-----+ +---+----+ +-----+
| R 1 X X Switch +---+ R 2 |
+-----+ +--------+ +-----+
--
Grant. . . .
unix || die
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