Hi Declan and Shahaf,

-----Original Message-----
From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Doherty, Declan
Sent: Tuesday, January 09, 2018 9:31 AM
To: Shahaf Shuler <redacted>; dev@dpdk.org
Subject: Re: [dpdk-dev] [RFC] tunnel endpoint hw acceleration enablement

On 24/12/2017 5:30 PM, Shahaf Shuler wrote:

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Hi Declan,

Hey Shahaf, apologies for the delay in responding, I have been out of office
for the last 2 weeks.

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Friday, December 22, 2017 12:21 AM, Doherty, Declan:

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This RFC contains a proposal to add a new tunnel endpoint API to DPDK
that when used in conjunction with rte_flow enables the configuration
of inline data path encapsulation and decapsulation of tunnel
endpoint network overlays on accelerated IO devices.

The proposed new API would provide for the creation, destruction, and
monitoring of a tunnel endpoint in supporting hw, as well as
capabilities APIs to allow the acceleration features to be discovered by

applications.

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Am not sure I understand why there is a need for the above control

methods.

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Are you introducing a new "tep device" ? > As the tunnel endpoint is
sending and receiving Ethernet packets from

the network I think it should still be counted as Ethernet device but with
more capabilities (for example it supported encap/decap etc..), therefore it
should use the Ethdev layer API to query statistics (for example).

No, the new APIs are only intended to be a method of creating, monitoring
and deleting tunnel-endpoints on an existing ethdev. The rationale for APIs
separate to rte_flow are the same as that in the rte_security, there is not a
1:1 mapping of TEPs to flows. Many flows (VNI's in VxLAN for example) can
be originate/terminate on the same TEP, therefore managing the TEP
independently of the flows being transmitted on it is important to allow
visibility of that endpoint stats for example.

I don't quite understand what you mean by tunnel and flow here. Can you define exactly what you mean? Flow is an overloaded word in our world. I think that defining it will make understanding the RFC a little easier.

Taking VxLAN, I think of the tunnel as including up through the VxLAN header, including the VNI. If you go by this definition, I would consider a flow to be all packets with the same VNI and the same 5-tuple hash of the inner packet. Is this what you mean by tunnel (or TEP) and flow here?

With these definitions, VPP for example might need up to a couple thousand TEPs on an interface and each TEP could have hundreds or thousands of flows. It would be quite possible to have 1 rte flow rule per TEP (or 2- ingress/decap and egress/encap). The COUNT action could be used to count the number of packets through each TEP. Is this adequate, or are you proposing that we need a mechanism to get stats of flows within each TEP? Is that the main point of the API? Assuming no need for stats on a per TEP/flow basis is there anything else the API adds?

I can't see how the existing
ethdev API could be used for statistics as a single ethdev could be supporting
may concurrent TEPs, therefore we would either need to use the extended
stats with many entries, one for each TEP, or if we treat a TEP as an attribute
of a port in a similar manner to the way rte_security manages an IPsec SA,
the state of each TEP can be monitored and managed independently of both
the overall port or the flows being transported on that endpoint.

Assuming we can define one rte_flow rule per TEP, does what you propose give us anything more than just using the COUNT action?

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As for the capabilities - what specifically you had in mind? The current

usage you show with tep is with rte_flow rules. There are no capabilities
currently for rte_flow supported actions/pattern. To check such capabilities
application uses rte_flow_validate.

I envisaged that the application should be able to see if an ethdev can
support TEP in the rx/tx offloads, and then the rte_tep_capabilities would
allow applications to query what tunnel endpoint protocols are supported
etc. I would like a simple mechanism to allow users to see if a particular
tunnel endpoint type is supported without having to build actual flows to
validate.

I can see the value of that, but in the end wouldn't the API call rte_flow_validate anyways? Maybe we don't add the layer now or maybe it doesn't really belong in DPDK? I'm in favor of deferring the capabilities API until we know it's really needed.  I hate to see special capabilities APIs start sneaking in after we decided to go the rte_flow_validate route and users are starting to get used to it.

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Regarding the creation/destroy of tep. Why not simply use rte_flow API

and avoid this extra control?

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For example - with 17.11 APIs, application can put the port in isolate mode,

and insert a flow_rule to catch only IPv4 VXLAN traffic and direct to some
queue/do RSS. Such operation, per my understanding, will create a tunnel
endpoint. What are the down sides of doing it with the current APIs?

That doesn't enable encapsulation and decapsulation of the outer tunnel
endpoint in the hw as far as I know. Apart from the inability to monitor the
endpoint statistics I mentioned above. It would also require that you
redefine the endpoints parameters ever time to you wish to add a new flow
to it. I think the having the rte_tep object semantics should also simplify the
ability to enable a full vswitch offload of TEP where the hw is handling both
encap/decap and switching to a particular port.

If we have the ingress/decap and egress/encap actions and 1 rte_flow rule per TEP and use the COUNT action, I think we get all but the last bit. For that, perhaps the application could keep  ingress and egress rte_flow template for each tunnel type (VxLAN, GRE, ..). Then copying the template and filling in the outer packet info and tunnel Id is all that would be required. We could also define these in rte_flow.h?

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To direct traffic flows to hw terminated tunnel endpoint the rte_flow
API is enhanced to add a new flow item type. This contains a pointer
to the TEP context as well as the overlay flow id to which the traffic flow is

associated.

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struct rte_flow_item_tep {
                struct rte_tep *tep;
                uint32_t flow_id;
}

Can you provide more detailed definition about the flow id ? to which field

from the packet headers it refers to?

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On your below examples it looks like it is to match the VXLAN vni in case of

VXLAN, what about the other protocols? And also, why not using the already
exists VXLAN item?

I have only been looking initially at couple of the tunnel endpoint procotols,
namely Geneve, NvGRE, and VxLAN, but the idea here is to allow the user to
define the VNI in the case of Geneve and VxLAN and the VSID in the case of
NvGRE on a per flow basis, as per my understanding these are used to
identify the source/destination hosts on the overlay network independently
from the endpoint there are transported across.

The VxLAN item is used in the creation of the TEP object, using the TEP
object just removes the need for the user to constantly redefine all the
tunnel parameters and also I think dependent on the hw implementation it
may simplify the drivers work if it know the exact endpoint the actions is for
instead of having to look it up on each flow addition.

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Generally I like the idea of separating the encap/decap context from the

action. However looks like the rte_flow_item has double meaning on this
RFC, once for the classification and once for the action.

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 From the top of my head I would think of an API which separate those, and

re-use the existing flow items. Something like:

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  struct rte_flow_item pattern[] = {
                 { set of already exists pattern  },
                 { ... },
                 { .type = RTE_FLOW_ITEM_TYPE_END } };

encap_ctx = create_enacap_context(pattern)

rte_flow_action actions[] = {
	{ .type RTE_FLOW_ITEM_ENCAP, .conf = encap_ctx} }

I not sure I fully understand what you're asking here, but in general for encap
you only would define the inner part of the packet in the match pattern
criteria and the actual outer tunnel headers would be defined in the action.

I guess there is some replication in the decap side as proposed, as the TEP
object is used in both the pattern and the action, possibly you could get away
with having no TEP object defined in the action data, but I prefer keeping the
API symmetrical for encap/decap actions at the shake of some extra
verbosity.

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...

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