Multiple IPv6 RAs and static routes with metric 1


First, let me thank you for all of your hard work in developing and maintaining network-manager. It makes life with a Linux laptop much simpler.

I have observed a behavior in network-manager in both Ubuntu (12.10) and Fedora (18). In the presence of multiple routers advertising defaults, n-m seems to insert a static default route for one of them, with metric 1. Here is example output from my Fedora system:

default via fe80::5054:ff:fe01:b6dc dev eth0  proto static  metric 1
default via fe80::5054:ff:fe01:b6dc dev eth0 proto ra metric 1024 expires 2sec default via fe80::5054:ff:fe2f:62c2 dev eth0 proto ra metric 1024 expires 9sec

The Ubuntu system's output looks similar.

I believe that the addition of the "static metric 1" route is incorrect, as static routes of this type persist even when the router in question is no longer doing router advertisements. In that case, the system will use that route in preference to the other router, which may still be doing router advertisements. This creates issues when multiple routers are correctly advertising on the same link, and the intention is to provide a failover capability, without the complications of a first hop redundancy protocol.

I am in control of both of the advertising routers and can enable debug if needed on either the client systems or the advertising routers (which are virtual Ubuntu systems running Quagga).

I have filed a bug with Ubuntu (, but this seemed like a better place to address this - I see that recently there has been some discussion about IPv6 semantics on this list and some recent patches for IPv6, so this discussion might be timely.


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