[CentOS] local routing puzzle

[lejeczek]

I forgot to mentioned, just to be clear, these IFs are all 
one node, the same one hos, its routing table:

10.5.6.0        0.0.0.0         255.255.255.0   U     350 
0        0 nm-team1
172.25.12.0     0.0.0.0         255.255.255.0   U     100 
0        0 p3p3
192.168.2.0     0.0.0.0         255.255.255.0   U     110 
0        0 em2
192.168.2.0     0.0.0.0         255.255.255.0   U     111 
0        0 em1

no default gateways, so you can see these are directly 
connected networks

$ traceroute -n 10.5.6.17 -i em1
traceroute to 10.5.6.17 (10.5.6.17), 30 hops max, 60 byte 
packets
  1  10.5.6.17  0.426 ms !X  0.393 ms !X  0.311 ms !X
$ traceroute -n 10.5.6.17 -i em2
traceroute to 10.5.6.17 (10.5.6.17), 30 hops max, 60 byte 
packets
  1  10.5.6.17  0.382 ms !X  0.326 ms !X  0.274 ms !X
$ traceroute -n 10.5.6.17 -i nm-team1
traceroute to 10.5.6.17 (10.5.6.17), 30 hops max, 60 byte 
packets
  1  10.5.6.17  0.407 ms !X  0.342 ms !X  0.294 ms !X
$ traceroute -n 10.5.6.17 -i p3p3
traceroute to 10.5.6.17 (10.5.6.17), 30 hops max, 60 byte 
packets
  1  * * *
  2  * * *
  3  * * *
  4  * * *

I was expecting kernel's network would know best, what to 
do, especially that: (enp6s0f0 is 10.5.6.17)

root at 10.5.6.17 ]$ ping 172.25.12.222 -I enp6s0f0
PING 172.25.12.202 (172.25.12.222) from 10.5.6.17 enp6s0f0: 
56(84) bytes of data.
64 bytes from 172.25.12.222: icmp_seq=1 ttl=64 time=0.396 ms

there are two switches and vlans, switches routes auto 
configured, no default gateways on the switches neither, to 
try to simplify & troubleshoot.

regards
L.

On 16/08/16 11:59, John R Pierce wrote:
> On 8/16/2016 3:53 AM, lejeczek wrote:
>>
>> $ ping 10.5.6.17 -I p3p3
>> PING 10.5.6.17 (10.5.6.17) from 172.25.12.202 p3p3: 
>> 56(84) bytes of data.
>>
>> and nothing, ping waits and no reply, Ctrl+C
>>
>> with such a simple setup rules based routing should not 
>> be involved, kernel should figure it out, right? 
>
> you specifically said to send that packet to an interface 
> on the wrong network, of course, its not going to get 
> through, unless there's an external route from that 
> network to the destination. I'm presuming there's a router 
> somewhere else between your 192.168.2.0/24 network and 
> 10.5.6.17, that would enable those ping -I em1/2 commands 
> to work.   note that the recipient of the ping needs to 
> have a route to get back to the source, too.
>
>
>
>