[v2,net-next,09/12] Documentation: networking: dsa: add paragraph for the MRP offload

Commit Message

Vladimir Oltean March 16, 2021, 11:24 a.m. UTC

From: Vladimir Oltean <[e-mail]>

Add a short summary of the methods that a driver writer must implement
for getting an MRP instance to work on top of a DSA switch.

Cc: Horatiu Vultur <[e-mail]>
Signed-off-by: Vladimir Oltean <[e-mail]>
---
 Documentation/networking/dsa/dsa.rst | 30 ++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

Comments

Horatiu Vultur March 16, 2021, 3:12 p.m. UTC | #1

The 03/16/2021 13:24, Vladimir Oltean wrote:
> 
> From: Vladimir Oltean <[e-mail]>
> 
> Add a short summary of the methods that a driver writer must implement
> for getting an MRP instance to work on top of a DSA switch.
> 
> Cc: Horatiu Vultur <[e-mail]>
> Signed-off-by: Vladimir Oltean <[e-mail]>
> ---
>  Documentation/networking/dsa/dsa.rst | 30 ++++++++++++++++++++++++++++
>  1 file changed, 30 insertions(+)
> 
> diff --git a/Documentation/networking/dsa/dsa.rst b/Documentation/networking/dsa/dsa.rst
> index e8576e81735c..0daafa2fb9eb 100644
> --- a/Documentation/networking/dsa/dsa.rst
> +++ b/Documentation/networking/dsa/dsa.rst
> @@ -757,6 +757,36 @@ can optionally populate ``ds->num_lag_ids`` from the ``dsa_switch_ops::setup``
>  method. The LAG ID associated with a bonding/team interface can then be
>  retrieved by a DSA switch driver using the ``dsa_lag_id`` function.
> 
> +IEC 62439-2 (MRP)
> +-----------------
> +
> +The Media Redundancy Protocol is a topology management protocol optimized for
> +fast fault recovery time for ring networks, which has some components
> +implemented as a function of the bridge driver. MRP uses management PDUs
> +(Test, Topology, LinkDown/Up, Option) sent at a multicast destination MAC
> +address range of 01:15:4e:00:00:0x and with an EtherType of 0x88e3.
> +Depending on the node's role in the ring (MRM: Media Redundancy Manager,
> +MRC: Media Redundancy Client, MRA: Media Redundancy Automanager), certain MRP
> +PDUs might need to be terminated locally and others might need to be forwarded.
> +An MRM might also benefit from offloading to hardware the creation and
> +transmission of certain MRP PDUs (Test).
> +
> +Normally an MRP instance can be created on top of any network interface,
> +however in the case of a device with an offloaded data path such as DSA, it is
> +necessary for the hardware, even if it is not MRP-aware, to be able to extract
> +the MRP PDUs from the fabric before the driver can proceed with the software
> +implementation. DSA today has no driver which is MRP-aware, therefore it only
> +listens for the bare minimum switchdev objects required for the software assist
> +to work properly. The operations are detailed below.
> +
> +- ``port_mrp_add`` and ``port_mrp_del``: notifies driver when an MRP instance
> +  with a certain ring ID, priority, primary port and secondary port is
> +  created/deleted.
> +- ``port_mrp_add_ring_role`` and ``port_mrp_del_ring_role``: function invoked
> +  when an MRP instance changes ring roles between MRM or MRC. This affects
> +  which MRP PDUs should be trapped to software and which should be autonomously
> +  forwarded.
> +
>  TODO
>  ====
> 
> --
> 2.25.1
> 

Reviewed-by: Horatiu Vultur <[e-mail]>

Patch

diff --git a/Documentation/networking/dsa/dsa.rst b/Documentation/networking/dsa/dsa.rst
index e8576e81735c..0daafa2fb9eb 100644
--- a/Documentation/networking/dsa/dsa.rst
+++ b/Documentation/networking/dsa/dsa.rst
@@ -757,6 +757,36 @@  can optionally populate ``ds->num_lag_ids`` from the ``dsa_switch_ops::setup``
 method. The LAG ID associated with a bonding/team interface can then be
 retrieved by a DSA switch driver using the ``dsa_lag_id`` function.
 
+IEC 62439-2 (MRP)
+-----------------
+
+The Media Redundancy Protocol is a topology management protocol optimized for
+fast fault recovery time for ring networks, which has some components
+implemented as a function of the bridge driver. MRP uses management PDUs
+(Test, Topology, LinkDown/Up, Option) sent at a multicast destination MAC
+address range of 01:15:4e:00:00:0x and with an EtherType of 0x88e3.
+Depending on the node's role in the ring (MRM: Media Redundancy Manager,
+MRC: Media Redundancy Client, MRA: Media Redundancy Automanager), certain MRP
+PDUs might need to be terminated locally and others might need to be forwarded.
+An MRM might also benefit from offloading to hardware the creation and
+transmission of certain MRP PDUs (Test).
+
+Normally an MRP instance can be created on top of any network interface,
+however in the case of a device with an offloaded data path such as DSA, it is
+necessary for the hardware, even if it is not MRP-aware, to be able to extract
+the MRP PDUs from the fabric before the driver can proceed with the software
+implementation. DSA today has no driver which is MRP-aware, therefore it only
+listens for the bare minimum switchdev objects required for the software assist
+to work properly. The operations are detailed below.
+
+- ``port_mrp_add`` and ``port_mrp_del``: notifies driver when an MRP instance
+  with a certain ring ID, priority, primary port and secondary port is
+  created/deleted.
+- ``port_mrp_add_ring_role`` and ``port_mrp_del_ring_role``: function invoked
+  when an MRP instance changes ring roles between MRM or MRC. This affects
+  which MRP PDUs should be trapped to software and which should be autonomously
+  forwarded.
+
 TODO
 ====