Universal Node Repository Summary
For who is interested to play with this software without having to install everything, a live playground is available here.
The Universal Node can be considered a sort of “datacenter in a box”, hence providing functions similar to an OpenStack cluster, but limited to a single server. In a nutshell, it handles the orchestration of compute and network resources, hence managing the complete lifecycle of computing containers (e.g., VMs, Docker, DPDK processes) and networking primitives (e.g., OpenFlow rules, logical switching instances, etc). It receives commands through a REST API according to the Network Functions Forwarding Graph (NF-FG) formalism, and takes care of implementing them on the physical node. Due to its peculiar characteristics, it can be executed either on a traditional server (e.g., workstation with Intel-based CPU) or on a resource-constrained device, such as a residential gateway.
More in detail, when it receives a command to deploy a new NF-FG, it does all the operations required to actually implement the requested graph:
- retrieve the most appropriate images for the selected virtual network functions (VNFs) through the datastore;
- configure the virtual switch (vSwitch) to create a new logical switching instance (LSI) and the ports required to connect it to the VNFs to be deployed;
- deploy and start the VNFs;
- translate the rules to steer the traffic into OpenFlow
flowmodmessages to be sent to the vSwitch (some
flowmodare sent to the new LSI, others to the LSI-0, i.e. an LSI that steers the traffic towards the proper graph.)
Similarly, the un-orchestrator takes care of updating or destroying a graph, when the proper messages are received.
An high-level overview of this software is given by the picture below.
As evident in the picture above the un-orchestrator includes several modules; the most important ones are the network controller and the compute controller, which are exploited to interact respectively with the vSwitch and the hypervisor(s).
The VNF-selector selects instead the best implementation for the required VNFs, according to some parameters such as the amount of CPU and RAM available on the Universal Node, or the efficiency of the network ports supported by the VNF itself (e.g., standard virtio vs. optimized ports). Moreover, the VNF scheduler optimizes the binding VNF/CPU core(s) by taking into account information such as how a VNF interacts with the rest of the NF-FG.
While the network and compute controllers are detailed in the following sections, the VNF-optimizer and the placement-optimizer have not been implemented yet, as their implementation is let as a future work.
The code of this module is available in the
orchestrator folder; additional sub-modules are used to provide optional functions (e.g., graphical interface).
Please check individual README's in each subfolder for more information.
The network controller
The network controller is the sub-module that interacts with the vSwitch. It consists of two parts:
- the Openflow controller(s): a new Openflow controller is created for each new LSI, which steers the traffic among the ports of the LSI itself;
- the switch manager: it creates/destroys LSIs, virtual ports, and more. In practice, it allows the un-orchestrator to interact with the vSwitch in order to perform management operations. Each virtual switch implementation (e.g., xDPd, OvS) may require a different implementation for the switch manager, according to the API exported by the vSwitch itself.
Currently, the un-orchestrator supports OpenvSwitch (OvS), the extensible DataPath daemon (xDPd) and the Ericsson Research Flow Switch (ERFS) as vSwitches, although further vSwiches can be supported by writing a module implementing a proper API. If you are interested to add the support for a new virtual switch, please check the file network_controller/switch_manager/README.md.
Note that, according to the picture above, several LSIs may be deployed on the UN. In particular, in the boot phase the network controller creates a first LSI (called LSI-0) that is connected to the physical interfaces and that will be connected to several other LSIs. Each one of these additional LSIs corresponds to a different NF-FG; hence, it is connected to the VNFs of such a NF-FG, and takes care of steering the traffic among them as required by the graph description. Instead the LSI-0, being the only one connected to the physical interfaces of the UN and to all the other graphs, dispatches the traffic entering into the node to the proper graph, and properly handles the packets already processed in a graph.
The compute controller
The compute controller is the sub-module that interacts with the virtual execution environment(s) (i.e., the hypervisor) and handles the lifecycle of a Virtual Network Function (i.e., creating, updating, destroying a VNF), including the operations needed to attach VNF ports already created on the vSwitch to the VNF itself. Each execution environment may require a different implementation for the compute controller, according to the commands supported by the hypervisor itself.
Currently, the prototype supports virtual network functions as (KVM) VMs, Docker, DPDK processes and native functions, although only a subset of them can be available depending on the chosen vSwitch. Also in this case, further execution environments can be supported through the implementation of a proper API. If you are interested to add the support for a new hypervisor, please check the file compute_controller/README.md.
Compute and network controllers: supported combinations
The following table shows the execution environments that are supported with the different vSwitches.
|Docker||KVM||KVM-DPDK (ivshmem)||DPDK processes||Native|
|OvS (OVSDB / OFconfig)||Yes||Yes||No (requires OvS-DPDK)||No (requires OvS-DPDK)||Yes|
* In this case the packet exchange between the virtual switch and the execution environment is not optimized.
The un-orchestrator natively supports the deployment of NF-FGs described with initial JSON-based format defined in WP5 and used in the initial part of the project.
If you plan instead to use the new XML-based format defined in WP3 that includes both top-down communication (for the actual forwarding graph) and bottom-up primitives (for resources and capabilities), you have also to run the virtualizer.
The datastore is an helper module that contains NF images and templates, NF-FGs, and more. It is exploited by the un-orchestrator each time that a NF must be started, in order to:
- retrieve the NF template(s)
- download the software image implementing the NF to be started Particularly, in case the NF-FG indicates a specific template for the network function (e.g., firewall_vmimage_abc), only such a template is retrieved from the datastore. Otherwise the universal node orchestrastor downloads all the templates implementing the required function (e.g., firewall), and will select one of them based on such internal policies.
The datastore can be installed either locally or on a remote server.
The Virtualizer is currently deprecated. Please refer to the documention available in that folder for more information.
This folder contains some examples of virtual network functions that are known to work on the UN.
This folder contains a nice web-based GUI that allows to draw an NF-FG and deploy it on the UN, as well as to visualize NF-FGs already deployed.
This folder contains some running use-cases for the UN, including configuration files and VNFs.