Hi, On Mon, Aug 22, 2022 at 02:55:09PM +0200, Kristof Provost wrote: > > Now, back to FreeBSD. > > > > - our code does not try to set metrics on FreeBSD > > - my reading of route(8) does not show me anything in that direction > > (metric, preference, administrative distance, ...) > > - I do not understand FreeBSD internals well enough to know whether > > it can be done at all, or not. > > > It???s rather poorly (i.e. not) documented, but it is possible to set a > route metric. It???s called a ???weight???, and not actually mentioned > in the man page. Or shown in netstat output. > > But: > > $ sudo route add 172.16.2.0/24 10.0.2.1 > add net 172.16.2.0: gateway 10.0.2.1 > $ sudo route add 172.16.2.0/24 -weight 2 10.0.2.254 > add net 172.16.2.0: gateway 10.0.2.254
Oh, this is interesting, and good to know.
What is the default weight? "1"?
> So we can add multiple routes for the same network, as long as they have
> a different gateway.
>
> The usual `netstat -rn` doesn???t show the weight. You have to use the
> json/xml output to get it:
>
> $ netstat -rn --libxo json | jq
> ???
> {
> "destination": "172.16.2.0/24",
> "gateway": "10.0.2.1",
> "flags": "UGS",
> "flags_pretty": [
> "up",
> "gateway",
> "static"
> ],
> "weight": 1,
> "interface-name": "bnxt0"
> },
Interesting :-)
[..]
> A higher weight gives a higher priority, so that???s the opposite of
> what Linux does with metric, I believe.
Right. Linux metrics are "lower is better", like a routing protocol
cost would do.
[..]
> If I???m understanding everything correctly it should be relatively
> simple to extend networking_freebsd.c to also set a weight for each
> route it installs.
> We???d have to convert the metric into a weight, which I think we could
> do as `weight = RT_MAX_WEIGHT - metric` (RT_MAX_WEIGHT is 16777215 /* 3
> bytes */).
>
> Can you try this?
Looks good, might work :-).
Will give this a try as soon as time permits - next 2-3 weeks might not
work out.
gert
--
"If was one thing all people took for granted, was conviction that if you
feed honest figures into a computer, honest figures come out. Never doubted
it myself till I met a computer with a sense of humor."
Robert A. Heinlein, The Moon is a Harsh Mistress
Gert Doering - Munich, Germany g...@greenie.muc.de
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