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- Motivation
- ==========
- One of the nice things about network namespaces is that they allow one
- to easily create and test complex environments.
- Unfortunately, these namespaces can not be used with actual switching
- ASICs, as their ports can not be migrated to other network namespaces
- (NETIF_F_NETNS_LOCAL) and most of them probably do not support the
- L1-separation provided by namespaces.
- However, a similar kind of flexibility can be achieved by using VRFs and
- by looping the switch ports together. For example:
- br0
- +
- vrf-h1 | vrf-h2
- + +---+----+ +
- | | | |
- 192.0.2.1/24 + + + + 192.0.2.2/24
- swp1 swp2 swp3 swp4
- + + + +
- | | | |
- +--------+ +--------+
- The VRFs act as lightweight namespaces representing hosts connected to
- the switch.
- This approach for testing switch ASICs has several advantages over the
- traditional method that requires multiple physical machines, to name a
- few:
- 1. Only the device under test (DUT) is being tested without noise from
- other system.
- 2. Ability to easily provision complex topologies. Testing bridging
- between 4-ports LAGs or 8-way ECMP requires many physical links that are
- not always available. With the VRF-based approach one merely needs to
- loopback more ports.
- These tests are written with switch ASICs in mind, but they can be run
- on any Linux box using veth pairs to emulate physical loopbacks.
- Guidelines for Writing Tests
- ============================
- o Where possible, reuse an existing topology for different tests instead
- of recreating the same topology.
- o Tests that use anything but the most trivial topologies should include
- an ASCII art showing the topology.
- o Where possible, IPv6 and IPv4 addresses shall conform to RFC 3849 and
- RFC 5737, respectively.
- o Where possible, tests shall be written so that they can be reused by
- multiple topologies and added to lib.sh.
- o Checks shall be added to lib.sh for any external dependencies.
- o Code shall be checked using ShellCheck [1] prior to submission.
- 1. https://www.shellcheck.net/
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