neutron: added test case to check connectivity using MTU sized frames
Properly configured setup must allow frames of network MTU size (as
reported by Neutron net-mtu API extension) through the network.
Sadly, Cirros images ship ping tools that don't support the -M argument
that allows to set Don't Fragment flag, so the only way to enforce it is
from outside the instance.
Change-Id: I1dd0633e48dbc9b67cd79e610e959b514304a4b5
Related-Bug: #1623876
diff --git a/tempest/common/utils/net_utils.py b/tempest/common/utils/net_utils.py
index f0d3da3..867b3dd 100644
--- a/tempest/common/utils/net_utils.py
+++ b/tempest/common/utils/net_utils.py
@@ -51,3 +51,23 @@
return addrs
msg = "Insufficient IP addresses available"
raise lib_exc.BadRequest(message=msg)
+
+
+def get_ping_payload_size(mtu, ip_version):
+ """Return the maximum size of ping payload that will fit into MTU."""
+ if not mtu:
+ return None
+ if ip_version == 4:
+ ip_header = 20
+ icmp_header = 8
+ else:
+ ip_header = 40
+ icmp_header = 4
+ res = mtu - ip_header - icmp_header
+ if res < 0:
+ raise lib_exc.BadRequest(
+ message='MTU = %(mtu)d is too low for IPv%(ip_version)d' % {
+ 'mtu': mtu,
+ 'ip_version': ip_version,
+ })
+ return res