Extend delay probe time

testVtiRekey_IPv6_in_IPv6 and  testVtiRekey_IPv4_in_IPv6 failed on a poor performance platform. They failed because one redundant NS packet is sent to probe neighbor host's mac address. During the test, RA is received, neighbor table's state became NUD_STALE. After one UDP packet is sent, state is changed to NUD_DELAY. There is 5s interval before state is changed to NUD_PROBE. If it is NUD_PROBE, NS is sent certainly. Some poor platform cannot send successfully all UDP packets in 5s, so NS is necessary to probe, since it is unexpected. For such platform, 10s is enough to finish to send all, so extend delay probe time

Bug: 123202162
Test: VtsKernelNetTest can pass
Change-Id: I98047d08e89896958de60f66e9b286564b52046f
diff --git a/net/test/xfrm_tunnel_test.py b/net/test/xfrm_tunnel_test.py
index 652a0c2..5f243cc 100755
--- a/net/test/xfrm_tunnel_test.py
+++ b/net/test/xfrm_tunnel_test.py
@@ -444,6 +444,11 @@
         cls._SetInboundMarking(netid, iface, True)
         cls._SetupTunnelNetwork(tunnel, True)
 
+        # On slower platforms, the test does not complete before the delay probe time fires.
+        # This causes the test to fail because of the unexpected NUD packet. b/123202162
+        if version == 6:
+          cls.SetSysctl("/proc/sys/net/ipv6/neigh/%s/delay_first_probe_time"
+                        % cls.GetInterfaceName(underlying_netid) , 10)
         if version == 4:
           cls.tunnelsV4[netid] = tunnel
         else: