On Thu, May 25, 2017 at 12:05 AM, Vasu M <[email protected]> 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.
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