On Thu, May 25, 2017 at 12:05 AM, Vasu M <vasu.kernel@gmail.com> wrote:
I would like to know from which version of Linux, ECMP is supported? I am trying to add a route with two next hops. Only one path gets added. And for the other path, the route says "RTNETLINK answers: File exists". I am not able to understand what's going on. The route prefix is not pointing to ecmp because metric is not given for static routes? How can I test multipath for a prefix that goes over 2 links?
I tried "echo 7 > /proc/sys/kernel/printk" and dmesg but I don't see anything related to route add events. Just wondering how I should approach this problem.
I am running the following versions on two devices running ONL.
*Linux localhost 3.16.43-OpenNetworkLinux #1 SMP Thu May 11 18:37:48 UTC 2017 x86_64 GNU/Linux* I tried the following :-
root@localhost:~# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 192.168.100.1 0.0.0.0 UG 0 0 0 ma1
10.10.10.0 0.0.0.0 255.255.255.0 U 0 0 0 fpPort2
20.20.20.0 0.0.0.0 255.255.255.0 U 0 0 0 fpPort13
192.168.100.0 0.0.0.0 255.255.255.0 U 0 0 0 ma1
root@localhost:~# arp -a
? *(20.20.20.2) at 00:a0:c9:00:00:01 [ether] on fpPort13 *
? (192.168.100.100) at f0:7f:06:1d:56:ff [ether] on ma1
? (192.168.100.1) at 18:b1:69:33:88:a4 [ether] on ma1
? (192.168.100.52) at cc:37:ab:7c:ca:16 [ether] on ma1
? (192.168.100.3) at c8:1f:66:f6:ea:07 [ether] on ma1
? *(10.10.10.2) at 00:a0:c9:00:00:01 [ether] on fpPort2*
ip route add 100.100.100.0/24 via 10.10.10.2
root@localhost:~# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 192.168.100.1 0.0.0.0 UG 0 0 0 ma1
10.10.10.0 0.0.0.0 255.255.255.0 U 0 0 0 fpPort2
20.20.20.0 0.0.0.0 255.255.255.0 U 0 0 0 fpPort13
100.100.100.0 10.10.10.2 255.255.255.0 UG 0 0 0 fpPort2
192.168.100.0 0.0.0.0 255.255.255.0 U 0 0 0 ma1
root@localhost:~# ip route add 100.100.100.0/24 via 20.20.20.2
*RTNETLINK answers: File exists*
Figured "ip route append" is used to add ECMP. I am, however, seeing some ECMP paths getting added to the rt table which seems to be a bug although the behavior is not consistent.