Link local vs global v6 next hop for BGP rotuer

[Ondrej Zajicek]

On Mon, Oct 10, 2022 at 11:25:23AM +0200, Alexander Zubkov wrote:
> Hi,
> 
> In documentation part it is written that the default for the option is
> "disabled". But in the code I see it chooses the value based on
> "gw_mode":
> > Different default for next_hop_prefer
> 
> Am I missing something or there is a typo?

Hi

The documentation is a remnant of the original design, where the option
was next_hop_prefer_global bool. Later i changed that to be more symmetric
(next_hop_prefer with NHP_GLOBAL / NHP_LOCAL), but forgot to update the
docs.

Note that for gw_mode == GW_DIRECT, even before the patch we prefererred
the global next hop to link-local (see bgp_apply_next_hop()), so that why
there is a different default based on gw_mode, but the second part
(switching next hop to link-local for gw_mode == GW_DIRECT) is not
implemented yet.


> On Mon, Oct 10, 2022 at 5:44 AM Ondrej Zajicek via Bird-users
> <bird-users at network.cz> wrote:
> >
> > On Wed, Sep 21, 2022 at 08:47:03AM +0000, Mazur, Dariusz wrote:
> > > Hello Ondrej,
> > > Thanks for quick response. Additional option to ignore link-local BGP next hops would help us a lot.
> >
> > Hello
> >
> > Done, here is a commit with BGP channel option 'next hop prefer global',
> > which makes BIRD to use global next hop instead of link-local:
> >
> > https://gitlab.nic.cz/labs/bird/-/commit/8f79e6b93e32a4eb7e4dda9bd4a9d04400b79d45

-- 
Elen sila lumenn' omentielvo

Ondrej 'Santiago' Zajicek (email: santiago at crfreenet.org)
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"To err is human -- to blame it on a computer is even more so."