NS4

An overview

Overview

NS4 is divided into control plane half and data plane half, which collectively simulate a complete network system with programmable data plane (PDP) . Developers simulate a controller by instantiating a ‘Controller Model‘ and simulate a P4 device by instantiating a ‘Programmable Data Plane Model‘. Traditional devices like router or switch are also supported in NS4 but omitted in the figure.

Workflow

The procedures to simulate a P4-enabled network are shown as numbers in figure.

1. configure the behavior of data plane by inputting a compiled P4 program to the P4 pipeline configurator;
2. create control plane and populate table entries to P4 devices, by either implementing a controller application inside the controller model or simply running an arbitrary controller application (such as ONOS) outside NS4;
3. add ports (maybe connected to various channels) to the PDP model.
4. At this point, we have this PDP model configured and functional as a P4 device. Next steps are building network topology, installing applications at terminal nodes and triggering the simulator.

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Controller Model

The brain of NS4

A controller does not directly manipulate table entries in P4 devices via function calls. Instead, it is created as an independent network component and populates tables to P4 devices via packets transmission, just in the real-world way. Also, we notice the fact that when focusing on simulating P4 devices, developing a controller application just to populate ta- ble entries can be an arduous but unnecessary work, so we make the controller model able to communicate with a controller application running outside NS4 process. This bridge connecting from P4 devices in NS4 process and controllers outside NS4 process eliminates unnecessary work of developing controller applications for simulation environment and also provides a method of testing general controller applications.

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Programmable Data Plane Model

The essence of NS4

Unlike fixed-function devices, P4 devices need setting up simulation environment to define their behaviors (see workflow paragraph). The core of the PDP model is a complete P4 pipeline which contains a parser, match-action tables, a deparser and buffers amid them. We then add a channel manager and a packet de/encapsulator beyond link layer to mask details of underlying channels and provide a uniform interface for the P4 pipeline. The channel manager expands the scope of simulatable P4 devices, from devices connected via NICs to ones connected via virtually any channel.

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Demo

Proof of the novel concepts

In order to further demonstrate the effectiveness and convenience of NS4, We orchestrate a user case of a typical campus network miniature with heterogeneous network involved, as depicted in the figure before.
During demonstration, we plan to demonstrate the detailed process of simulating the campus network as described above using a local laptop. On site, we will provide an interactive user interface for attendees to (1) explore interested information such as perfor- mance statistics (2) dynamically operate NS4 by giv- ing instructions to the simulated network through a user interface. Attendees’ possible instructions can per- form di↵erent types of operations like, changing network topology, configuration of P4 devices, population of ta- bles and many more. The showcase will also demonstrate at length the installation of NS4 environment on Linux operating system, configuration of P4 devices, setting up the controllers, population of table entries, triggering simulator and evaluation of critical and interested statistics in real NS4 usage scenarios.

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ns-3 Integration

Under development.

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Others

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