OpenvSwitch Port Mirror in OpenStack Neutron

OpenvSwitch Port Mirror in OpenStack Neutron

• Preface

I recently built an OpenStack Environment Based on VXLAN and found that the package to dump ovs interfaces is still quite troublesome. After many efforts, find some trouble shooting methods in the network environment of openstack.

In addition to common tools such as ping, host, traceroute, tcpdump, ip neighbor, arp, and arping, you can also use port mirror to dump ovs packets.

• Environment

There are two nodes in my environment. node1 enables Nova and Neutron, and node2 only enables Nova-related services.

Ovs environment of Node1:

sudo ovs-vsctl show47a7cda2-1263-485a-8ae4-1be7cf53ed44    Bridge br-tun        fail_mode: secure        Port "veth0"            Interface "veth0"        Port patch-int            Interface patch-int                type: patch                options: {peer=patch-tun}        Port br-tun            Interface br-tun                type: internal        Port "vxlan-0a674d0e"            Interface "vxlan-0a674d0e"                type: vxlan                options: {df_default="true", in_key=flow, local_ip="10.103.77.13", out_key=flow, remote_ip="10.103.77.14"}    Bridge br-int        fail_mode: secure        Port "tapb5e83be9-f9"            tag: 2            Interface "tapb5e83be9-f9"                type: internal        Port "qvo42d126bc-e1"            tag: 2            Interface "qvo42d126bc-e1"        Port int-br-ex            Interface int-br-ex                type: patch                options: {peer=phy-br-ex}        Port patch-tun            Interface patch-tun                type: patch                options: {peer=patch-int}        Port br-int            Interface br-int                type: internal    Bridge br-ex        Port "eth1"            Interface "eth1"        Port br-ex            Interface br-ex                type: internal        Port phy-br-ex            Interface phy-br-ex                type: patch                options: {peer=int-br-ex}    ovs_version: "2.0.2"

What I want to do is dump all the packages of the patch-int interface on the br-tun so that we can see what the package looks like after the br-tun conversion.

• First, create an interface of the veth type

ip link add type vethip link set veth0 upip link set veth1 up

• Add veth0 to br-tun.

ovs-vsctl add-port br-tun "veth0"

• Create port mirror

ovs-vsctl -- set Bridge br-tun mirrors=@m \-- --id=@veth0 get Port veth0 \-- --id=@patch-int get Port patch-int \-- --id=@br-tun get Port br-tun \-- --id=@m create Mirror name=veth select-src-port=@br-tun,@patch-int \select-dst-port=@br-tun,@patch-int output-port=@veth0

After successful execution, a mirror id is output. You can use

ovs-vsctl list bridge

Check whether mirror is in outout.

_uuid               : 18303d75-8715-408d-b9d7-5ef0424734f2controller          : []datapath_id         : "0000763d30188d40"datapath_type       : systemexternal_ids        : {}fail_mode           : secureflood_vlans         : []flow_tables         : {}ipfix               : []mirrors             : [d2bcbe65-ae4c-4b88-9172-cf84dae39d0e]name                : br-tunnetflow             : []other_config        : {}ports               : [3eb258b0-f9db-4dfa-bbd5-697162f26142, 6755f9ce-a8fa-4b52-ba3a-06c798e12b9b, c45bbbd7-6baf-4774-b0e4-493d74ae0589, ffcf5619-baaf-469a-bb2d-9016ede95c92]protocols           : ["OpenFlow10"]sflow               : []status              : {}stp_enable          : false 

• Finally, use tcpdump to view the package on veth0 (I usually output the output to the cap file and view it with wireshark, which is very intuitive)

sudo tcpdump -i veth0 -vv -ne -w veth0.cap

When you use wireshark to view the packages, you will find that these packages have been translated into normal packages instead of VXLAN packages, so you cannot see the tunnel id of vxlan.

 

References:

VXLAN: https://tools.ietf.org/pdf/rfc7348.pdf

Neutron Troubleshooting: http://docs.openstack.org/openstack-ops/content/network_troubleshooting.html

The following is a collection of Openstack related knowledge for you to see if you like it:

Install and deploy Openstack on Ubuntu 12.10

Ubuntu 12.04 OpenStack Swift single-node deployment Manual

OpenStack cloud computing quick start tutorial

Deploying OpenStack for enterprises: what should be done and what should not be done

CentOS 6.5 x64bit quick OpenStack Installation

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