Re: [iproute2 net-next] ip route: Add RTM_F_LOOKUP_TABLE flag and show table id

[David Ahern <dsa@cumulusnetworks.com>]

On 9/21/15 4:03 PM, David Miller wrote:
> From: David Ahern <dsa@cumulusnetworks.com>
> Date: Mon, 21 Sep 2015 16:03:00 -0600
>
>> On 9/21/15 3:58 PM, David Miller wrote:
>>> I think if it always gave MAIN in older kernels, iproute should
>>> continue
>>> to do so.
>>>
>>> You can't just remove the table ID output just because you disagree
>>> with
>>> the semantics given by old kernels.
>>>
>>
>> Current semantics are maintained. Kernel was hardcoded to return main;
>> iproute2 was hardcoded to not show main.
>
> Since iproute2 always showed MAIN, it should conitnue to do so when
> run on older kernels.
>
> And again this is regardless of whether you disagree with those
> semantics or not.
>

Dave:

ip does *not* show the table id or string today:

root@vm-wheezy2:~# ip route get 10.2.1.254
10.2.1.254 dev eth1 src 10.2.1.2
cache


With the new flag a AND kernel that supports it ip will only show the 
table id IF it is not main:

root@vm-wheezy2:~# ./ip route get 10.0.0.20
10.0.0.20 dev eth0  src 10.0.0.2
     cache

root@vm-wheezy2:~# ./ip route get 10.2.1.254
10.2.1.254 dev eth1  table 10  src 10.2.1.2
     cache

That's my point. I have not changed existing users.