> Is it possible to have two default routes (less specific: two routes with
> the same destination/mask) to different devices/gateways with different
> priorities/metrics and have the kernel choose the better one? Else it isn't
> possible to change the default route on demand _reliably_, with having a
> fallback to the diald "approach" daemon (i.e. diald as of now can't do it
> anyway) which is re-activated whenever the newly activated default goes
> down.
I'm not sure what it is that diald can't do here. Diald happily
does double routing on the proxies and managed interfaces.
Here's my routing table while the link is down:
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
158.152.1.222 0.0.0.0 255.255.255.255 UH 1 0 2 sl0
132.147.160.16 0.0.0.0 255.255.255.255 UH 1 0 1 sl1
172.16.1.0 0.0.0.0 255.255.255.0 U 0 0 45 eth0
132.147.0.0 132.147.160.16 255.255.0.0 UG 1 0 0 sl1
127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 15 lo
0.0.0.0 0.0.0.0 0.0.0.0 U 1 0 8 sl0
sl0 is a diald managed link to Demon (my ISP) with the real interface
being a synch PPP link over ISDN. sl1 is a two way link to one of
our customers (yes, I *know* that is a shitty IP net for them to use!)
Note the metric.
Now when the Demon link comes up here's my routing table again:
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
158.152.1.222 0.0.0.0 255.255.255.255 UH 0 0 1 ippp0
158.152.1.222 0.0.0.0 255.255.255.255 UH 1 0 2 sl0
132.147.160.16 0.0.0.0 255.255.255.255 UH 1 0 1 sl1
172.16.1.0 0.0.0.0 255.255.255.0 U 0 0 50 eth0
132.147.0.0 132.147.160.16 255.255.0.0 UG 1 0 0 sl1
127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 19 lo
0.0.0.0 0.0.0.0 0.0.0.0 U 0 0 14 ippp0
0.0.0.0 0.0.0.0 0.0.0.0 U 1 0 9 sl0
Note the ippp0 interface which is now active. Note the doubled routes
that diald sets up. Note the metrics. Yes, the kernel picks the
lowest metric. Diald will actually forward any packets it receives
on the proxy and tell me about doing it - if it ever gets any.
This set up takes the link up and down several times a day, day after
day, week after week with no problems (other than that damn stupid
IP net :-( ).
Mike
-- .----------------------------------------------------------------------. | Mike Jagdis | Internet: mailto:mike@roan.co.uk | | Roan Technology Ltd. | | | 54A Peach Street, Wokingham | Telephone: +44 118 989 0403 | | RG40 1XG, ENGLAND | Fax: +44 118 989 1195 | `----------------------------------------------------------------------'