1. Accelerating OpenStack Neutron
with Intel DPDK based Open vSwitch
Alexander Shalimov
http://arccn.ru/
ashalimov@arccn.ru
@alex_shali
@arccnnews

2. OpenStack
• Open source software for building private and
public cloud.
– Create VMs, attach storage to them, and connect
them into virtual topology
2

3. OpenStack Neutron
• Neutron = OpenStack networking
• Main responsibility is to provide virtual network
to the tenant:
– Setup L2 network
– Setup L3 network (DHCP, gateway, ACL)
• Plugin architecture
– Linux Bridge
– Open vSwitch
– Ryu OpenFlow controller
– Nicira NVP
3

4. • Based on Open vSwitch, virtual software switch
• The plugin supports three operational modes:
– FLAT: virtual networks share on L2 domain
– VLAN: each virtual network has its own VLAN tag
– GRE: traffic goes through NVGRE tunnels and separated by
XID.
OVS/GRE setup:
+: Very popular, any Ethernet fabric, 2^32 networks
-: Bad performance and scalability (between VMs
located on different compute nodes)
4
Open vSwitch plugin

5. OVS/GRE plugin architecture
5
VM VM VM VM
br-int
br-ex
Compute Node
VMs
OVS bridgespatch port
GRE port
NIC
physical layer
??? SLOW
http://www.openstack.org/summit/openstack-summit-hong-kong-2013/session-videos/presentation/open-vswitch-and-its-usage-in-neutron

6. OVS/GRE plugin bottlenecks
6
br-ex
patch port
GRE port
NIC
Linux Networking
Stack
Standard networking stack is
slow, yes. It’s well know fact. But
the traffic speed is even slower.
• Heavily layered
• Allocation
• ….

7. GRE port in OVS
• OVS lays finishing of GRE packet encapsulation on
networking stack.
7
MACs IPs Payload
VM
OVS GRE port
MACs IPs PayloadGRE
Linux Networking Stack
MACs IPs PayloadGREMACs IPs
Require more work for route and arp lookups. Thus, slower!

8. Accelerating Neutron
• Don’t use Linux Networking Stack - use special
fast paths instead:
– Intel DPDK,
– Netmap.
• Open vSwitch should be integrated with such
fast paths.
• Our choose to start was Intel DPDK vSwitch.
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9. Intel DPDK vSwitch
• Basically it is OVS daemon connected to DPDK-based
datapath
– https://github.com/01org/dpdk-ovs
• But it required some work for OpenStack:
– patch ports,
– multiple datapaths/bridges,
– GRE stack
• Still need route and arp lookups.
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10. Our GRE port architecture
• GRE port should fully be responsible for packet
encapsulation.
• Tasks of GRE port:
– Determine local IP.
• Must specify both local and remote IPs;
– Determine MAC addresses
• Maintain our own ARP table;
– What NIC to send
• Route table is encoded into main flow table and
encapsulated packets are returned back to the datapath and
matched again against the flow table.
• Still suit OpenStack Neutron plugin
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11. Our GRE port architecture
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VM VM
GREGRE NIC
NIC
Original Our
Flow table Flow table
Linux
networking
stack
DPDK
OVS DPDK OVS

12. Experimental evaluation
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Accelerated OVS Original OVS
VLAN
physical-to-physical 5 Mpps 1.1 Mpps
physical-to-vm 3.3 Mpps 0.44 Mpps
GRE
physical-to-physical 1.6 Mpps 0.22 Mpps
physical-to-vm 1.12 Mpps 0.11 Mpps
* 10 Gb channel
** 64 bytes UDP packets
*** theoretical max is 15Mpps
**** Intel Xeon E3-1240 2.4GHz/6
***** IVSHMEM VM connection (~0.6Mpps without)
It is 5 times performance improving!

13. Questions?
• The code is available in ARCCN github:
– arccn.github.io
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http://arccn.ru/ ashalimov@arccn.ru
@alex_shali
@arccnnews