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Network foundations A05

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Reusing a Network Component

Overview

This example loads pre-saved network components, retrieves the Base and Ebgp layers within them, and then extends the existing network: adding hosts to the current autonomous system, introducing new autonomous systems and exchange points, and configuring corresponding peering connections. It demonstrates how to build scenarios further from a reusable base network to reduce redundant topology coding work. You can save networks commonly used in courses or research as components, add different services, adjust interconnection relationships or set control conditions on the same foundation, facilitating reuse and experimental comparison.

Using a Pre-built Component

In Example A01-transit-as, we have saved the emulator in a file as a component. In this example, we demonstrate how we can load it into another emulation.

Standard Arguments

python examples/basic/A05_components/components.py amd
python examples/basic/A05_components/components.py --platform amd --output examples/basic/A05_components/output
python examples/basic/A05_components/components.py --dumpfile examples/basic/A05_components/components.bin

Supported arguments:

  • amd|arm: optional legacy platform argument.
  • --platform amd|arm: named platform argument.
  • --output PATH: output folder for Docker compiler results.
  • --dumpfile PATH: save a serialized emulator instead of compiling Docker output.
  • --component-file PATH: location for the temporary component loaded from A01.
  • --override / --no-override: control whether existing output is replaced.
  • --skip-render: compile without calling emu.render() first.

Loading a Pre-Built Component

We can load a pre-built component. All the layers of the component will be loaded. If the current emulator already has layers, merging will be conducted if needed.

emu = Emulator()
emu.load('../01-transit-as/base_component.bin')

Getting the Layer Reference

If we want to make changes to any layer, we first need to get the layer object. In this example, we need to make changes to the base and ebgp layers, so we get their references.

base: Base       = emu.getLayer('Base')
ebgp: Ebgp       = emu.getLayer('Ebgp')

Adding Host to an Existing Autonomous System

We can also modify an existing AS from the component. We just need to get the reference of this AS first, and then use the standard API to make changes. In this example, we have a new host to AS-151.

as151 = base.getAutonomousSystem(151)
as151.createHost('web-2').joinNetwork('net0')

Adding a New Autonomous System

Once we get the base layer, we can add new elements to the layer, such as a new autonomous system, a new internet exchange, etc. The code to do this is the same as that in building an emulation from scratch. In this example, we created a new autonomous system AS-154, and then peer it with the other two ASes from the component at the internet exchanges ix100 and `ix101, which are also from the component.

ebgp.addPrivatePeering(100, 151, 153, abRelationship = PeerRelationship.Provider)
ebgp.addPrivatePeering(101, 152, 153, abRelationship = PeerRelationship.Peer)

Adding a New Internet Exchange

In the example, we also show how to create an new internet exchange, and then peer two ASes in this IX. We do need to create a new BGP router for an AS and place it inside this IX, if the AS wants to peer with others in this IX.

base.createInternetExchange(102)

TestRunner Lifecycle

python seedemu/testing/cli.py all examples/basic/A05_components/example.yaml --artifact-dir ci-artifacts/a05

The runtime test dynamically inspects the generated Compose labels instead of hard-coding service names. It verifies that the added AS151 web host, AS154, and IX102 are generated, and that the new web services can reach each other.

Source: SEED Emulator · A05 README

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