I'm trying to achieve communication across an OVS switch between to VMs
connected together via an ovs bridge. I was able to do this with a ovs
bridge with to generic libvirt 'network' types. I'm failing to
replicate using DPDK vhost.
In libvirt 'network' scenario vnet[0,1] ports are added to the bridge
that also has a port for the physical NIC on the system. The switch
defaults to its L2 function and I can access the system's IP addresses.
In the DPDK vhost scenario, the client server connections get made, but
the host running the switch doesn't put the ports on the IP stack. I
haven't been able to route a packet between the VMs. Do I need to
create "flows" to mimic a single wire type of connection? I don't need
L2 function, but I did think it might be possible to move IP packets
through DPDK. Any pointers appreciated.
[root@cn03 openvswitch]# ovs-vsctl show
d78a22bb-84c7-46d4-9625-6c9c38aeeff7
Bridge br0
Port br0
Interface br0
type: internal
Port vnet1
Interface vnet1
Port vnet0
Interface vnet0
Port enP5p1s0f0
Interface enP5p1s0f0
Bridge ovs-br0
datapath_type: netdev
Port dpdkvhostclient0
Interface dpdkvhostclient0
type: dpdkvhostuserclient
options:
{vhost-server-path="/usr/local/var/run/openvswitch/dpdkvhostclient0"}
Port dpdkvhostclient1
Interface dpdkvhostclient1
type: dpdkvhostuserclient
options:
{vhost-server-path="/usr/local/var/run/openvswitch/dpdkvhostclient1"}
Port ovs-br0
Interface ovs-br0
type: internal
ovs_version: "2.13.1"
Yes, you definitely need to setup flow rules once you connect the VMs
with OVS/DPDK. Here's the script I use to setup a learning switch which
should get you base functionality you're looking for:
#!/bin/bash
PATH=/usr/share/openvswitch/scripts:$PATH
MAX_PORT=2
# Make sure we're running as root
if [[ $EUID -ne 0 ]]; then
echo "This script must be run as root"
exit 1
fi
# Check command line arguments for the bridge name
BRIDGE=$1
[ -z "$BRIDGE" ] && BRIDGE=ovsbr0
# Verify that OVS is running and the bridge exists
ovs-vsctl br-exists $BRIDGE > /dev/null 2>&1
RETVAL=$?
if [ $RETVAL -ne 0 ]; then
echo "Can't find OVS bridge $BRIDGE, exiting ..."
exit 1
fi
# For example, "0-3,7" becomes "0,1,2,3,7".
# Requires two arguments:
# $1 - The string to be expanded
# $2 - The list of CPUs being returned
function parse_range {
arr=()
IFS=', ' read -a ranges <<< $1
for range in "${ranges[@]}"; do
IFS=- read start end <<< "$range"
[ -z "$start" ] && continue
[ -z "$end" ] && end=$start
for ((i = start; i <= end; i++)); do
arr+=($i)
done
done
eval $2=$(IFS=,;printf "%s" "${arr[*]}")
}
# Set the OFPORTS flows for the learning switch
PORT_RANGE="1-${MAX_PORT}"
PORT_LIST=""
parse_range $PORT_RANGE PORT_LIST
echo "Configuring learning switch for ports $PORT_RANGE ..."
#######################################################################
# Bridge is setup, program the flow configuration
#######################################################################
echo "Clearing current flow setup for $BRIDGE..."
ovs-ofctl del-flows $BRIDGE
echo "Configuring flows on $BRIDGE for learning switch..."
#=======================================================================
# Setup table0, admission control
#=======================================================================
# Drop packets with a multicast source address (illegal packet)
ovs-ofctl add-flow $BRIDGE \
"table=0, dl_src=01:00:00:00:00:00/01:00:00:00:00:00, actions=drop"
# Drop spanning tree packets
ovs-ofctl add-flow $BRIDGE \
"table=0, dl_dst=01:80:c2:00:00:00/ff:ff:ff:ff:ff:f0, actions=drop"
# Pass all other frames onto table1
ovs-ofctl add-flow $BRIDGE "table=0, priority=0, actions=resubmit(,1)"
#=======================================================================
# Setup table1, MAC learning
#=======================================================================
ovs-ofctl add-flow $BRIDGE \
"table=1 actions=learn(table=10, NXM_OF_ETH_DST[]=NXM_OF_ETH_SRC[], \
load:NXM_OF_IN_PORT[]->NXM_NX_REG0[0..15]), \
resubmit(,2)"
#=======================================================================
# Setup table2, destination lookup
#=======================================================================
# Always forward multicast/broadcast packets
ovs-ofctl add-flow $BRIDGE \
"table=2 priority=99 dl_dst=01:00:00:00:00:00/01:00:00:00:00:00 \
actions=resubmit(,3)"
# Lookup the destination in table 10, move the packet on to table 3
ovs-ofctl add-flow $BRIDGE \
"table=2 priority=50 actions=resubmit(,10), resubmit(,3)"
#=======================================================================
# Setup table3, output processing
#=======================================================================
# Handle broadcast/multicast packets (OpenFlow will prevent
# the packet from being re-transmitted out the ingress port)
ovs-ofctl add-flow $BRIDGE "table=3 reg0=0 actions=${BRIDGE},${PORT_LIST}"
# Setup the unicast flows for the vhost interfaces
for i in $(seq 1 $MAX_PORT); do
ovs-ofctl add-flow $BRIDGE "table=3 reg0=$i actions=$i"
done
# Don't forget the bridge's tap interface to the host
ovs-ofctl add-flow $BRIDGE "table=3 reg0=65534 actions=local"
echo "New flow configuration for $BRIDGE..."
ovs-ofctl dump-flows $BRIDGE
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