netdev - Re: [Questions] Some issues about IPv4/IPv6 nexthop route

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Message-ID: <078061ce-1411-d150-893a-d0a950c8866f@kernel.org>
Date: Mon, 28 Aug 2023 09:06:25 -0600
From: David Ahern <dsahern@...nel.org>
To: Hangbin Liu <liuhangbin@...il.com>, Ido Schimmel <idosch@...sch.org>
Cc: Stephen Hemminger <stephen@...workplumber.org>, netdev@...r.kernel.org,
 "David S . Miller" <davem@...emloft.net>, Eric Dumazet
 <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
 Paolo Abeni <pabeni@...hat.com>, Thomas Haller <thaller@...hat.com>
Subject: Re: [Questions] Some issues about IPv4/IPv6 nexthop route

On 8/28/23 1:53 AM, Hangbin Liu wrote:
> On Thu, Jul 27, 2023 at 05:45:02PM +0300, Ido Schimmel wrote:
>>> Since the route are not merged, the nexthop weight is not shown, which
>>> make them look like the same for users. For IPv4, the scope is also
>>> not shown, which look like the same for users.
>>
>> The routes are the same, but separate. They do not form a multipath
>> route. Weight is meaningless for a non-multipath route.
>>
>>> But there are 2 issues here:
>>> 1. the *type* and *protocol* field are actally ignored
>>> 2. when do `ip monitor route`, the info dumpped in fib6_add_rt2node()
>>>    use the config info from user space. When means `ip monitor` show the
>>>    incorrect type and protocol
>>>
>>> So my questions are, should we show weight/scope for IPv4?
> 
> Here is the first one. As the weight/scope are not shown, the two separate
> routes would looks exactly the same for end user, which makes user confused.

Asked and answered many times above: Weight has no meaning on single
path routes; it is not even tracked if I recall correctly.

> So why not just show the weight/scope, or forbid user to add a non-multipath
> route with weight/scope?

That is a change to a uAPI we can not do at this point.

> 
>>> How to deal the type/proto info missing for IPv6?
> 
> What we should do for this bug? The type/proto info are ignored when
> merge the IPv6 nexthop entries.

I need more information; this thread has gone on for a long time now.