Default Gateway for a system v/s Default gateway per Interface

[Andrew Jeffery]

On Mon, 27 Apr 2020, at 20:41, Ratan Gupta wrote:
> Thanks Patrick, William for sharing the feedbacks
> 
> I will start working on the changes.
> 
> 
> 
> On 4/24/20 11:15 PM, William Kennington wrote:
> > Sounds good to me, we have needed this for a long time because the current gateway configuration breaks our v6 stack with multiple NICs.
> > 
> > On Fri, Apr 24, 2020 at 8:21 AM Patrick Williams <patrick at stwcx.xyz> wrote:
> >> On Fri, Apr 24, 2020 at 08:36:26PM +0530, Ratan Gupta wrote:
> >>  > ~~~~~~~~~~~~~
> >>  > Kernel IP routing table
> >>  > Destination Gateway Genmask Flags MSS Window irtt 
> >>  > Iface
> >>  > 0.0.0.0 19.168.2.1 0.0.0.0 UG 0 0 0 
> >>  > eth0
> >>  > 0.0.0.0 10.10.10.1 0.0.0.0 UG 0 0 0 
> >>  > eth1
> >>  > ~~~~~~~~~~~~~~
> >>  > 
> >>  > Kernel will first try using the default gateway having higher metric 
> >>  > value and then fall back to the lower.
> >> 
> >>  I'm not seeing us with an interface to adjust the metric for an
> >>  interface. I think we need to add that at the same time? 
> Not now, As per my testing if metric value is not defined and both the routes
> 
> having same metric then kernel tries one after other. We can bring the metric
> 
> later.

This sounds like implementation-defined behaviour. Is that the case? If so it's 
not something we should be relying on.

Andrew