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panrg / path-properties

A Vocabulary of Path Properties
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Slightly rephrase transparency definition and add more examples #53

Closed cyrill-k closed 3 years ago

cyrill-k commented 3 years ago

I'm not sure what to do about the "endpoint transparency" ("host transparency"?), or the explicit communication with a host. If the node has communicated with the host, say, out-of-band, and then modifies the packet based on that, can that be just another piece of meta-information?

I guess that is true, however even in such a case, the relevant piece of meta-information is how to identify the flow and associate it to host, with which the node communicated to perform a specific action. And the identification relies on the existence and content of protocol headers and payloads, which we cover with our definition. So, for example to model RFC8558 style interactions between hosts and on-path nodes using our path terminology, we could say that the explicit communication with a host changes the transparency property of the node.

I'm not sure we should attempt to capture a broader concept of "endpoint transparency", e.g., whether an endpoint is aware of a particular node, and whether it communicates with the node explicitly. Maybe we can get away with just making this awareness or communication be "meta-information", which we don't define further?

I would suggest to keep the definition as it is right now and keep the definition of meta-information open-ended.

renghardt commented 3 years ago

I agree with your reasoning regarding the "endpoint transparency" - let's keep the definition as-is.

So I think this PR can be merged after changing the firewall example. :slightly_smiling_face:

cyrill-k commented 3 years ago

I changed the firewall example. If you agree with the changes, you can merge the PR.

renghardt commented 3 years ago

Looks good to me now, so I'm merging it.