Brian J. Murrell wrote:
On Sun, 2008-03-23 at 05:36 +0000, Andrew Suffield wrote:
It does, but there's a factorial explosion in the number of rules
required (you stack up a 3-way route first, then three 2-way routes,
etcetera). The right solution is to teach the kernel to trim down
nexthop rules when it loses interfaces, rather than deleting them
outright. As usual, the right solution is a pain to implement.

It's not even that.  As has been observed, you cannot have multiple
default routes at the same cost, so once the nexthop routing goes away
you effectively have only one default route, whichever one was installed
with the lowest cost.

For single line-failure tolerance, only N+1 routes are needed; the N-way, followed by N (N-1)-ways. After a single-line failure, there will only be one route remaining; the one that omitted the failed line.

-Tom
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