[R3.1-mainline-2738]: ecmp without policy have issues

[alok kumar]

This bug is in reference with PR 1566650.

In service-chain with scaling, disabling policy on all the interfaces does not work as expected and have below issues:

traffic path: VM1(1.1.1.4)->SI-3-instances->VM2(2.2.2.4)

1. flow is created even when policy is disabled on all the interfaces involved.

    9804<=>322632 2.2.2.4:11960 1 (1)
                         2.2.2.6:0
(Gen: 3, K(nh):26, Action:F, Flags:, E:1, QOS:-1, S(nh):35, Stats:0/0, SPort 61073)

   252020<=>356536 2.2.2.4:11960 1 (2->3)
                         1.1.1.4:0
(Gen: 2, K(nh):59, Action:F, Flags:, QOS:-1, S(nh):28, Stats:2/196, SPort 55109)

   322632<=>9804 2.2.2.6:11960 1 (1->1)
                         2.2.2.4:0
(Gen: 2, K(nh):95, Action:F, Flags:, QOS:-1, S(nh):144, Stats:2/196, SPort 61471)

   356536<=>252020 1.1.1.4:11960 1 (2->3)
                         2.2.2.4:0
(Gen: 2, K(nh):30, Action:F, Flags:, E:0, QOS:-1, S(nh):31, Stats:0/0, SPort 55437)

2. sometime there is traffic loss for ping reply, I saw VM2 sending reply but it does reach VM1 sometime.looks like it's because of symmetry issue. reply follows the different path sometime, have verified it through tcpdump.

setup info:
env.roledefs = {
    'all': [host1,host2,host3,host4],
    'cfgm': [host1],
    'openstack':[host2],
    'control': [host1,host2],
    'compute': [host3,host4],
    'collector': [host1],
    'webui': [host1],
    'database': [host1],
    'build': [host_build],
}

env.hostnames = {
    'all': ['nodec64', 'nodeg18', 'nodec62', 'nodec12']
}

[Ashok Singh (ashoksr)]

Issue is in vrouter for traffic originating from ECMP source as pert discussion with Anand.

[Anand H. Krishnan (anandhk)]

Fix:

https://github.com/Juniper/contrail-vrouter/commit/b4980e5c9bb4bcddafa0d747bee72dba5856c496

[Hari Prasad Killi (haripk)]

R3.1 : http://github.org/Juniper/contrail-vrouter/commit/75f51c86ac7634169696f44231b842b26a476191