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Internet services B00

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Building a Mini Internet

Overview

This example creates a mini Internet containing 6 Internet exchanges, 5 transit ASes, and 12 stub ASes to demonstrate how application traffic traverses multiple networks. It also demonstrates configurations for accessing the real Internet and connecting external machines through a VPN. The entire network can be saved as a component for other examples to load. You can first examine cross-AS connectivity and transit relationships, then add DNS, PKI, or distributed applications to the same foundation. You can also adjust routing policies and links to compare how network changes affect application access.

Mini Internet

This is a comprehensive example. It creates 6 Internet exchanges, 5 transit ASes, and 12 stub ASes. One of the ASes (AS-99999) is a real-world autonomous system, which announces the real-work network prefixes to the emulator. Packets to these prefixes will be routed out to the real Internet. Another AS (AS-152) allows machines from the outside to join the emulation (via VPN), so they can interact with the machines inside the emulator.

The emulator generated from this example is saved to a component file, and be used by several other examples as the basis.

The public Python entrypoint is still:

from examples.internet.B00_mini_internet import mini_internet

mini_internet.run(dumpfile='./base_internet.bin')
mini_internet.run(dumpfile='./base_internet.bin', hosts_per_as=2)

Other examples use this API to build their underlying network topology, so the run(dumpfile=None, hosts_per_as=2, ...) signature is kept compatible.

Using Utility Functions

We have created a few utility functions to help make it easy to create autonomous systems. The following example creates a transit AS (AS-2), which has a presence at 3 Internet exchanges (ix-100, ix-101, and ix-102). It also creates two internal networks to connect the 3 BGP routers of this AS.

Makers.makeTransitAs(base, 2, [100, 101, 102],
       [(100, 101), (101, 102)]
)

The following example creates a stub AS (AS-153), which has a presence at ix-101. Three hosts will be created for this AS, one running a web service, and the other two not running any service.

Makers.makeStubAs(emu, base, 153, 101, [web, None, None])

Standard Arguments

The example accepts both the legacy platform argument and the newer named arguments:

python examples/internet/B00_mini_internet/mini_internet.py amd
python examples/internet/B00_mini_internet/mini_internet.py --platform amd --output examples/internet/B00_mini_internet/output
python examples/internet/B00_mini_internet/mini_internet.py --dumpfile examples/internet/B00_mini_internet/base_internet.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.
  • --hosts-per-as N: number of hosts created in each stub AS.
  • --override / --no-override: control whether existing output is replaced.
  • --skip-render: compile without calling emu.render() first.

TestRunner Lifecycle

This example includes an example.yaml manifest for seedemu.testing. Run these commands from the repository root:

python seedemu/testing/cli.py clean examples/internet/B00_mini_internet/example.yaml
python seedemu/testing/cli.py compile examples/internet/B00_mini_internet/example.yaml --artifact-dir ci-artifacts/b00
python seedemu/testing/cli.py build examples/internet/B00_mini_internet/example.yaml --artifact-dir ci-artifacts/b00
python seedemu/testing/cli.py up examples/internet/B00_mini_internet/example.yaml --artifact-dir ci-artifacts/b00
python seedemu/testing/cli.py probe examples/internet/B00_mini_internet/example.yaml --artifact-dir ci-artifacts/b00
python seedemu/testing/cli.py test examples/internet/B00_mini_internet/example.yaml --artifact-dir ci-artifacts/b00
python seedemu/testing/cli.py down examples/internet/B00_mini_internet/example.yaml --artifact-dir ci-artifacts/b00

The full lifecycle can also be run with:

python seedemu/testing/cli.py all examples/internet/B00_mini_internet/example.yaml --artifact-dir ci-artifacts/b00

The manifest declares runner: internet because it uses Internet-style probes. The readiness stage checks representative transit routers, stub routers, and stub hosts. The probe stage checks cross-AS reachability across different parts of the mini Internet. The test_runtime.py program demonstrates custom runtime validation, including a check for the AS154 host with the customized IP address.

Source: SEED Emulator · B00 README

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