multiple switch definition p4 files

[duanev]

I would like to use the h1<->s1<->s2<->s3<->h2 topology with two different switch p4 definitions (s1,s3 = switch_a, s2 = switch_b). Can this be done?

[theojepsen]

Running a different P4 program on each switch is not currently supported.

It shouldn't be too difficult to add this feature. The hardest part will be figuring out how change the manifest schema. Right now, there is only one P4 program per p4app.json manifest file. To support multiple programs, we would have to change the schema so that a program can be associated with a specific switch.

[duanev]

I suppose conditionals based on the switch config could be an immediate workaround?

[theojepsen]

p4app started off with idea that you'd specify a p4 program in the manifest, and then run it with different targets. The top-level p4app script compiles the p4 program, and passes it as an argument to one of the targets, which is a separate script. "multiswitch" is one of these targets.

In order to support multiple programs, we would have to redesign the manifest, and the flow between the scripts. For example, some targets only support a single p4 program -- if you had multiple programs, which one would you pass to these targets?

If you can propose an elegant solution (or even better, a PR), that would be great!

[theojepsen]

Hi @duanev

With the new version of p4app:
#54
you can specify a different P4 program per switch:
https://github.com/theojepsen/p4app/blob/tj/v2/examples/two-programs.p4app/main.py#L24

[robertsoule-barefoot]

Fixed by #54.