[P4-dev] Are metadatas shared between ingress and egress?

Mihai Budiu mbudiu at vmware.com
Thu Nov 9 13:21:45 EST 2017


This is a simple question with a complicated answer.
In the old version of P4 (p4-14) the user-defined metadata is visible both in ingress and egress. Some of the "intrinsic" or "standard" metadata is visible only in some parts, but to know which is which you have to read the spec.

In the new version of P4 (p4-16) there is no metadata, the metadata depends on the architecture that you are compiling for. There is an architecture called v1model.p4 which emulates the old architecture as much as possible.

In neither architecture can you have a table shared between ingress and egress.

Mihai

From: P4-dev [mailto:p4-dev-bounces at lists.p4.org] On Behalf Of wenxuemin
Sent: Thursday, November 9, 2017 4:27 AM
To: p4-dev <p4-dev at lists.p4.org>
Subject: [P4-dev] Are metadatas shared between ingress and egress?

Hi everyone,

Are metadatas shared between ingress control flow and egress control flow in p4?

what about tables? can the same table
applied both in ingress control flow and egress control flow?
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