Comment 87 for bug 1636654

Reviewed: https://review.opencontrail.org/43510
Committed: http://github.com/Juniper/contrail-vrouter/commit/87c2f0f9de803fb500a6618dd946ca380eeed15b
Submitter: Zuul v3 CI (<email address hidden>)
Branch: master

commit 87c2f0f9de803fb500a6618dd946ca380eeed15b
Author: Kiran Kasim <email address hidden>
Date: Mon Jun 4 15:13:38 2018 -0700

EVPN type 5 vRouter changes

The following vRouter changes are done for supporting EVPN type 5:
1) Introduce a new nh flag NH_FLAG_L3_VXLAN
2) On tx side, if the flag is set, overwrite the L2 packet's smac and
dmac with local vrouter MAC and dst vrouter MAC
(which is set in nh_vxlan_tun_l3_mac)
3) On rx side, no change
4) Introduce a new structure for vxlan tunnel which contains the
nh_vxlan_tun_l3_mac field
5) Change L2 VXLAN fields to the above structure so that
same VXLAN structure gets used for both L2 and L3
6) Enhance the nh utility to add type-5 routes using the flag l3_vxlan

Refer review comments here: https://review.opencontrail.org/#/c/41285/
Partial-Bug: 1636654
Implements: blueprint https://blueprints.launchpad.net/opencontrail/+spec/evpn-type-5

Change-Id: I70f5c163b7acb46cadc730946653f98fe670323a