Hello Yi Yang,
We are using your docker image docker-ovs:yyang to test stuff in ODL-
SFC Carbon. Today we found out that packets sent through an vxlan-gpe
tunnel are not accepted by the other VTEP.
This is the port sending the packets in OVS 1.
Port "tundaae6e77d14"
Interface "tundaae6e77d14"
type: vxlan
options: {dst_port="4880", exts=gpe, key=flow,
local_ip="172.19.0.3", "nshc1"=flow, "nshc2"=flow, "nshc3"=flow,
"nshc4"=flow, nsi=flow, nsp=flow, remote_ip=flow}
Here is the output of tcpdump where the packets can be seen:
16:53:11.114196 IP 172.19.0.3.58481 > 172.19.0.2.4880: UDP, length 120
16:53:12.113785 IP 172.19.0.3.58481 > 172.19.0.2.4880: UDP, length 120
And this is the port in OVS 2 which receives the packets but for
unknown reasons, it does not accept them:
Port "tun28619095a5a"
Interface "tun28619095a5a"
type: vxlan
options: {dst_port="4880", exts=gpe, key=flow,
local_ip="172.19.0.2", "nshc1"=flow, "nshc2"=flow, "nshc3"=flow,
"nshc4"=flow, nsi=flow, nsp=flow, remote_ip=flow}
The traffic going through other vxlan ports (not gpe and using
destination port 4789) works. I am bit lost on what might be the
problem, so any hint you can provide us will be appreciated. I found
out one thing which perhaps is the source of the problem. In the
packets working this is the vxlan header:
0800 0000 0000 0000
The packets not working have the following vxlan header:
0c00 0003 0000 0800
Look at the first byte, the packets working have 000001000 and the ones
not working 00001100. I checked the VXLAN spec and it says:
VXLAN Header: This is an 8-byte field that has:
- Flags (8 bits): where the I flag MUST be set to 1 for a valid
VXLAN Network ID (VNI). The other 7 bits (designated "R") are
reserved fields and MUST be set to zero on transmission and
ignored on receipt.
Not all are set to 0! could it be that the docker container where OVS2 is
running drops the packets because it is expecting all flag bits to be 0 except
for the one specifying VNI?
Thanks,
Manuel
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