Skydive is “an open source real-time network topology and protocols analyzer”. It is a tool (with CLI and web interface) to help analyze and debug your network (OpenStack, OpenShift, containers, …).

The Data Plane Development Kit (DPDK) is a set of data plane libraries and network interface controller drivers for fast packet processing. http://dpdk.org/

As Skydive uses flow probes to analyze packets, thanks to gopacket. As the bandwidth used by Software Defined Networks increases, we need a solution to capture and analyze packets at high speed from switch port mirroring.

Let’s setup a demo environment

The demo setup is a switch with a 10Gbits/s port configured as port mirroring and a dedicated host running Skydive Agent with the DPDK configuration above.

Two hosts running VMs and containers will be named dpdk1 and dpdk3.

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Skydive compilation

First we must re-compile, Skydive. This is because the DPDK flow probe has strong version dependencies between the go-yanff projects and its dependencies.

# cd $GOPATH/src/github.com/skydive-project/skydive
# make WITH_DPDK=true
# echo 256 | sudo tee /proc/sys/vm/nr_hugepages
# sudo modprobe uio
# sudo insmod ./dpdk/dpdk-17.08/x86_64-native-linuxapp-gcc-install/lib/modules/$(uname -r)/extra/dpdk/rte_kni.ko
# sudo insmod ./dpdk/dpdk-17.08/x86_64-native-linuxapp-gcc-install/lib/modules/$(uname -r)/extra/dpdk/igb_uio.ko

Feel free to install the rte_kni.ko and igb_uio.ko on your system and add a hugepage sysctl rule to /etc/sysctl.d/50-dpdk.conf.

DPDK quick configuration

On fedora userspace helper :

# dnf install -y dpdk-tools
# dpdk_nic_bind --status
Network devices using DPDK-compatible driver
============================================
0000:05:00.0 'Ethernet Controller 10-Gigabit X540-AT2' drv=ixgbe unused=igb_uio
0000:05:00.1 'Ethernet Controller 10-Gigabit X540-AT2' drv=ixgbe unused=igb_uio

Bind/map the DPDK driver to the first physical port

# dpdk_nic_bind -b igb_uio 0000:05:00.0

Configure your switch in port mirroring, to send a copy of flow traffic to the first physical port

Skydive configuration

In the agent yaml file, we need to enable the dpdk probe by adding these lines :

dpdk:
  # DPDK port listening flows from
  ports:
      - 0
  #    - 1
  # nb workers per port
  workers: 4
  # debug message every n seconds
  # debug: 1

This configures the agent to set up the DPDK flow probe to capture traffic from the first physical port card.

Flows

On a VM hosted on dpdk1, generate some ICMP traffic to a VM hosted on dpdk3

vm1: # ping vm2

Now let’s enable traffic capture on the DPDK ports

# skydive --conf /tmp/skydive.yaml client capture create --gremlin "G.V().Has('Type', 'dpdkport')"

Let’s see the captured traffic

# skydive --conf /tmp/skydive.yaml client topology  query --gremlin "G.V().Has('Type', 'dpdkport').Flows()"

This expression retrieves all the flows captured by a DPDK port.

Note : These commands could be done and seen on the web interface too, on the Capture, Flows tabs

Performance

During DPDK flow probe basic performance testing, I was able to achieve higher throughput on one worker by injecting traffic with tcpreplay.

The DPDK flow probe is configured to dispatch packets between workers based on a calculated L3 hash.

Conclusion

Using the DPDK flow probe is huge step in capturing real traffic behavior on physical infrastructure and have much better performance compared to the default afpacket probe.

Project site: http://skydive.network

GitHUB: https://github.com/skydive-project/skydive

Documentation: https://skydive-project.github.io/skydive

The YouTube channel with some demo videos

Mailing list: skydive-dev@redhat.com

IRC: #skydive-project on irc.freenode.net