FD.io CSIT Logical Topologies

FD.io CSIT Logical Topologies #

CSIT VPP performance tests are executed on physical testbeds. Based on the packet path thru server SUTs, three distinct logical topology types are used for VPP DUT data plane testing:

  1. NIC-to-NIC switching topologies.
  2. VM service switching topologies.
  3. Container service switching topologies.

NIC-to-NIC Switching #

The simplest logical topology for software data plane application like VPP is NIC-to-NIC switching. Tested topologies for 2-Node and 3-Node testbeds are shown in figures below.

Server Systems Under Test (SUT) run VPP application in Linux user-mode as a Device Under Test (DUT). Server Traffic Generator (TG) runs T-Rex application. Physical connectivity between SUTs and TG is provided using different drivers and NIC models that need to be tested for performance (packet/bandwidth throughput and latency).

From SUT and DUT perspectives, all performance tests involve forwarding packets between two (or more) physical Ethernet ports (10GE, 25GE, 40GE, 100GE). In most cases both physical ports on SUT are located on the same NIC. The only exceptions are link bonding and 100GE tests. In the latter case only one port per NIC can be driven at linerate due to PCIe Gen3 x16 slot bandwidth limiations. 100GE NICs are not supported in PCIe Gen3 x8 slots.

Note that reported VPP DUT performance results are specific to the SUTs tested. SUTs with other processors than the ones used in FD.io lab are likely to yield different results. A good rule of thumb, that can be applied to estimate VPP packet thoughput for NIC-to-NIC switching topology, is to expect the forwarding performance to be proportional to processor core frequency for the same processor architecture, assuming processor is the only limiting factor and all other SUT parameters are equivalent to FD.io CSIT environment.

VM Service Switching #

VM service switching topology test cases require VPP DUT to communicate with Virtual Machines (VMs) over vhost-user virtual interfaces.

Two types of VM service topologies are tested:

  1. “Parallel” topology with packets flowing within SUT from NIC(s) via VPP DUT to VM, back to VPP DUT, then out thru NIC(s).
  2. “Chained” topology (a.k.a. “Snake”) with packets flowing within SUT from NIC(s) via VPP DUT to VM, back to VPP DUT, then to the next VM, back to VPP DUT and so on and so forth until the last VM in a chain, then back to VPP DUT and out thru NIC(s).

For each of the above topologies, VPP DUT is tested in a range of L2 or IPv4/IPv6 configurations depending on the test suite. Sample VPP DUT “Chained” VM service topologies for 2-Node and 3-Node testbeds with each SUT running N of VM instances is shown in the figures below.

In “Chained” VM topologies, packets are switched by VPP DUT multiple times: twice for a single VM, three times for two VMs, N+1 times for N VMs. Hence the external throughput rates measured by TG and listed in this report must be multiplied by N+1 to represent the actual VPP DUT aggregate packet forwarding rate.

For “Parallel” service topology packets are always switched twice by VPP DUT per service chain.

Note that reported VPP DUT performance results are specific to the SUTs tested. SUTs with other processor than the ones used in FD.io lab are likely to yield different results. Similarly to NIC-to-NIC switching topology, here one can also expect the forwarding performance to be proportional to processor core frequency for the same processor architecture, assuming processor is the only limiting factor. However due to much higher dependency on intensive memory operations in VM service chained topologies and sensitivity to Linux scheduler settings and behaviour, this estimation may not always yield good enough accuracy.

Container Service Switching #

Container service switching topology test cases require VPP DUT to communicate with Containers (Ctrs) over memif virtual interfaces.

Three types of VM service topologies are tested in |csit-release|:

  1. “Parallel” topology with packets flowing within SUT from NIC(s) via VPP DUT to Container, back to VPP DUT, then out thru NIC(s).
  2. “Chained” topology (a.k.a. “Snake”) with packets flowing within SUT from NIC(s) via VPP DUT to Container, back to VPP DUT, then to the next Container, back to VPP DUT and so on and so forth until the last Container in a chain, then back to VPP DUT and out thru NIC(s).
  3. “Horizontal” topology with packets flowing within SUT from NIC(s) via VPP DUT to Container, then via “horizontal” memif to the next Container, and so on and so forth until the last Container, then back to VPP DUT and out thru NIC(s).

For each of the above topologies, VPP DUT is tested in a range of L2 or IPv4/IPv6 configurations depending on the test suite. Sample VPP DUT “Chained” Container service topologies for 2-Node and 3-Node testbeds with each SUT running N of Container instances is shown in the figures below.

In “Chained” Container topologies, packets are switched by VPP DUT multiple times: twice for a single Container, three times for two Containers, N+1 times for N Containers. Hence the external throughput rates measured by TG and listed in this report must be multiplied by N+1 to represent the actual VPP DUT aggregate packet forwarding rate.

For a “Parallel” and “Horizontal” service topologies packets are always switched by VPP DUT twice per service chain.

Note that reported VPP DUT performance results are specific to the SUTs tested. SUTs with other processor than the ones used in FD.io lab are likely to yield different results. Similarly to NIC-to-NIC switching topology, here one can also expect the forwarding performance to be proportional to processor core frequency for the same processor architecture, assuming processor is the only limiting factor. However due to much higher dependency on intensive memory operations in Container service chained topologies and sensitivity to Linux scheduler settings and behaviour, this estimation may not always yield good enough accuracy.