Re: [EXT] Re: [RFC, net-next] net: qos: introduce a frer action to implement 802.1CB

Hi Vladimir,

Vladimir Oltean [off-list ref] writes:

Hi Vinicius,

On Wed, Sep 29, 2021 at 10:25:58AM +0000, Xiaoliang Yang wrote:

quoted

Hi Vinicius,

On Sep 29, 2021 at 6:35:59 +0000, Vinicius Costa Gomes wrote:

quoted

quoted

This patch introduce a frer action to implement frame replication and
elimination for reliability, which is defined in IEEE P802.1CB.

An action seems, to me, a bit too limiting/fine grained for a frame replication
and elimination feature.

At least I want to hear the reasons that the current hsr/prp support cannot be
extended to support one more tag format/protocol.

And the current name for the spec is IEEE 802.1CB-2017.

802.1CB can be set on bridge ports, and need to use bridge forward
Function as a relay system. It only works on identified streams,
unrecognized flows still need to pass through the bridged network
normally.

But current hsr/prp seems only support two ports, and cannot use the
ports in bridge. It's hard to implement FRER functions on current HSR
driver.

You can see chapter "D.2 Example 2: Various stack positions" in IEEE 802.1CB-2017,
Protocol stack for relay system is like follows:

             Stream Transfer Function
                |             |
                |        Sequence generation
                |            Sequence encode/decode
  Stream identification        Active Stream identification
                |              |
                |        Internal LAN---- Relay system forwarding
                |                        |        |
                MAC                    MAC        MAC

Use port actions to easily implement FRER tag add/delete, split, and
recover functions.

Current HSR/PRP driver can be used for port HSR/PRP set, and tc-frer
Action to be used for stream RTAG/HSR/PRP set and recover.

Did Xiaoliang answer your question satisfactorily? :)

Oh, yes, the answer was very good. I was taking some time to read the
802.1CB spec, and try to think how things would fit together so I can
ask better questions next time :-)


Cheers,
-- 
Vinicius