[GLLUG] openwrt routing failing unexpectedly.

[Tim Woodall]

I'm having a routing problem that I don't understand. I'm trying to
setup a backup route to allow me to access an ipmi console even when the
normal router goes down.

I'm trying to get an openwrt wireless router to advertise a low priority
route but two things are happening that I don't expect:

1. It's seeing the route it's advertising. I don't expect that based on
the kernel settings.

2. The route seems to be breaking the normal route even though it has a
lower priority - higher metric.

Good routing table:
default from 2001:dead:beef:3::/64 via fe80::216:3eff:fee0:8001 dev wlan0 proto static  metric 512 
default from 2001:dead:beef:8003::/64 via fe80::216:3eff:fee1:8001 dev br-lan  proto static  metric 512 
2001:dead:beef:3::/64 dev wlan0  proto static  metric 256 
2001:dead:beef:8003::/64 dev br-lan  proto static  metric 256 
fe80::/64 dev br-lan  proto kernel  metric 256 
fe80::/64 dev wlan0  proto kernel  metric 256 
fe80::/64 dev wlan0-1  proto kernel  metric 256

Bad routing table:
default from 2001:dead:beef:3::/64 via fe80::216:3eff:fee0:8001 dev wlan0 proto static  metric 512 
default from 2001:dead:beef:8003::/64 via fe80::216:3eff:fee1:8001 dev br-lan  proto static  metric 512 
2001:dead:beef:3::/64 from 2001:dead:beef:8003::/64 via fe80::e695:6eff:fe43:8589 dev br-lan  proto static  metric 640 
2001:dead:beef:3::/64 dev wlan0  proto static  metric 256 
2001:dead:beef:8003::/64 dev br-lan  proto static  metric 256 
fe80::/64 dev br-lan  proto kernel  metric 256 
fe80::/64 dev wlan0  proto kernel  metric 256 
fe80::/64 dev wlan0-1  proto kernel  metric 256


The only difference is that extra 2001:dead:beef:3::/64 route. But I
thought this should be ignored as it has a higher metric than the other
2001:dead:beef:3::/64 route. Am I misunderstanding something?


And why is the route appearing in the first place?
cat /proc/sys/net/ipv6/conf/*/accept_ra_from_local 
0
0
0
0
0
0
0
0
0
0
0
0

The one bit that confuses me is the "from" in the routing table. That
doesn't appear on my other machines and it's quoting the /64 on the
interface, not the link local address that I would otherwise have
expected. (I'd expect the from to be the same as the via address)

Has anyone seen anything like this - or know where I'm going wrong?

Tim.