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P4: a high-level language for programming protocol-independent packet processors

p4.org

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Re: P4: a high-level language for programming protocol-independent packet processors

#11

Post by eric_bullington »

andy_ppp wrote: post #10
eric_bullington wrote: post #8

Earlier quoted context omitted.

It's pretty cool. I built a lexer/parser for the p4 language in Lua, with the intention of then building a "runtime" for it out of the Snabb networking toolkit (amusingly, I also finished most of a p4 lexer/parser in Elixir before switching to Lua). I don't think be able to build a full p4 implementation with Snabb running as a substrate (although it's been 6 months since I last worked on it, and am blanking at the m…

Cool stuff! Any reason why you switched to Lua from Elixir and any links to github with the code?

Well, I switched to Lua because Snabb apps are built in Lua, and because the Snabb toolkit will ideally provide a lot of functionality for the runtime that I won't have to build myself. And Snabb is really quite impressive in itself.

That said, Elixir is an awesome language, and lovely to write lexer/parsers in. I took me only a few hours to build a functioning parser in Elixir, compared to several days to build one in Lua.

The p4 parser/lexer in Lua is here: https://github.com/esbullington/snabbp4

Next step would be to generate the parse graph.

Re: P4: a high-level language for programming protocol-independent packet processors

#12

Post by slrz »

sigcode wrote: post #5

mininet, which this project uses, appears to be written only for linux? is this project linux only?

To be fair, I can't think of another OS that directly supports the things Mininet wants to do. To make it work on other platforms, they'd first have to implement those from scratch there.

Does FreeBSD nowadays provide some form of network isolation like it is available with Linux network namespaces? Nothing relevant shows up in the likely places, so I don't think it does.

Re: P4: a high-level language for programming protocol-independent packet processors

#14

Post by peterclary »

tthayer wrote: post #13

I thought 'perforce' when I saw the headline. Perforce is something I'm stuck with at my current job, unfortunately.

Agreed. P4 is synonymous for Perforce. Did the project authors not do a cursory google first?

As for "unfortunately", what don't you like about it, apart from it not being what you're used to from elsewhere? I've used Visual Sourcesafe, Perforce and git, and Perforce seems like a perfectly decent source control system.

However, I won't deny that it would be nice to be able to manage multiple revisions locally so that I can explore different approaches and easily backtrack without having to commit to the central server.

Re: P4: a high-level language for programming protocol-independent packet processors

#16

Post by gaius »

peterclary wrote: post #14
tthayer wrote: post #13

I thought 'perforce' when I saw the headline. Perforce is something I'm stuck with at my current job, unfortunately.

Agreed. P4 is synonymous for Perforce. Did the project authors not do a cursory google first? As for "unfortunately", what don't you like about it, apart from it not being what you're used to from elsewhere? I've used Visual Sourcesafe, Perforce and git, and Perforce seems like a perfectly decent source control system. However, I won't deny that it would be nice to be able to manage multiple revisions locally so that…

Right, it's not very fashionable, but both Google and MS are using Perforce for their own work... Normally the industry just slavishly imitates whatever Google does!

Re: P4: a high-level language for programming protocol-independent packet processors

#17

Post by pyvpx »

slrz wrote: post #12
sigcode wrote: post #5

mininet, which this project uses, appears to be written only for linux? is this project linux only?

To be fair, I can't think of another OS that directly supports the things Mininet wants to do. To make it work on other platforms, they'd first have to implement those from scratch there. Does FreeBSD nowadays provide some form of network isolation like it is available with Linux network namespaces? Nothing relevant shows up in the likely places, so I don't think it does.

there are vnet jails that behave similarly.

Re: P4: a high-level language for programming protocol-independent packet processors

#19

Post by eric_bullington »

superbaconman wrote: post #9
eric_bullington wrote: post #8

Earlier quoted context omitted.

It's pretty cool. I built a lexer/parser for the p4 language in Lua, with the intention of then building a "runtime" for it out of the Snabb networking toolkit (amusingly, I also finished most of a p4 lexer/parser in Elixir before switching to Lua). I don't think be able to build a full p4 implementation with Snabb running as a substrate (although it's been 6 months since I last worked on it, and am blanking at the m…

I'm hesitant to pick up another network protocol after OpenFlow. Lots of vendors claimed to support it, but only a handful took an honest shot at a decent implementation.

Just to be clear, p4 isn't actually a network protocol. It's a programming language, a DSL for programming network protocols. Small but significant difference between the two. But you're correct that it will require native support among router/switch vendors to be worth using.

Actually, p4 is aimed a solving a lot of the problems with OpenFlow that led to the situation you describe: incomplete support by vendors of all the different versions of OpenFlow. That's because each individual network protocol supported had to be written into the OpenFlow spec, thus the proliferation of versions. Whereas with p4, the vendors basically just provide a hardware runtime for the p4 language, and you install whichever protocols you wish to support (or write it yourself, if it's custom or new). It also has the potential to work very well with a scaled-down version of OpenFlow.

I'm not an SDN expert and am probably not doing justice to p4 with my description above, but it is important to realize this isn't just another network protocol. It would be like describing the Python or JS as just another program (the interpreter), and not as a program capable of running other programs.

Re: P4: a high-level language for programming protocol-independent packet processors

#20

Post by tthayer »

peterclary wrote: post #14
tthayer wrote: post #13

I thought 'perforce' when I saw the headline. Perforce is something I'm stuck with at my current job, unfortunately.

Agreed. P4 is synonymous for Perforce. Did the project authors not do a cursory google first? As for "unfortunately", what don't you like about it, apart from it not being what you're used to from elsewhere? I've used Visual Sourcesafe, Perforce and git, and Perforce seems like a perfectly decent source control system. However, I won't deny that it would be nice to be able to manage multiple revisions locally so that…

The company I work at has Perforce tied to a homegrown code review tool that really makes it painful to use and in reality that's my main gripe with having to use it.
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