[dpdk-users] Tracking pipeline ports.

[dpdk-users] Tracking pipeline ports.

[Gadre Nayan]

Hi,

I wanted to understand the purpose of the f_track function.

In the IP_pipeline example there are 2 instances where the f_track is used.

1. pipeline_firewall:
static int pipeline_firewall_track(void *pipeline, __rte_unused
uint32_t port_in,
        uint32_t *port_out)
{
        struct pipeline *p = (struct pipeline *) pipeline;

        /* Check input arguments */
        if ((p == NULL) ||
                (port_in >= p->n_ports_in) ||
                (port_out == NULL))
                return -1;

        if (p->n_ports_in == 1) {
                *port_out = 0;
                return 0;
        }

        return -1;
}

2. Passthrough:

static int
pipeline_passthrough_track(void *pipeline, uint32_t port_in, uint32_t *port_out)
{
        struct pipeline *p = (struct pipeline *) pipeline;

        /* Check input arguments */
        if ((p == NULL) ||
                (port_in >= p->n_ports_in) ||
                (port_out == NULL))
                return -1;

        *port_out = port_in / p->n_ports_in;
        return 0;
}

1. What is a actual use of this function ?
Quoting the documentation:
"In some cases, it is useful for a pipeline instance to get
application level information related to pipeline connectivity, such
as to identify the output link (e.g. physical NIC port) where one of
its output ports connected, either directly or indirectly by
traversing other pipeline instances."

2. The 1st condition check remains same in both. But in pass-through
port_out is assigned some value. what does this mean ?

Re: [dpdk-users] Tracking pipeline ports.

[Singh, Jasvinder]

> -----Original Message-----
> From: users [mailto:users-bounces@dpdk.org] On Behalf Of Gadre Nayan
> Sent: Monday, July 18, 2016 4:42 PM
> To: users@dpdk.org
> Subject: [dpdk-users] Tracking pipeline ports.
> 
> Hi,
> 
> I wanted to understand the purpose of the f_track function.
> 
> In the IP_pipeline example there are 2 instances where the f_track is used.
> 
> 1. pipeline_firewall:
> static int pipeline_firewall_track(void *pipeline, __rte_unused uint32_t
> port_in,
>         uint32_t *port_out)
> {
>         struct pipeline *p = (struct pipeline *) pipeline;
> 
>         /* Check input arguments */
>         if ((p == NULL) ||
>                 (port_in >= p->n_ports_in) ||
>                 (port_out == NULL))
>                 return -1;
> 
>         if (p->n_ports_in == 1) {
>                 *port_out = 0;
>                 return 0;
>         }
> 
>         return -1;
> }
> 
> 2. Passthrough:
> 
> static int
> pipeline_passthrough_track(void *pipeline, uint32_t port_in, uint32_t
> *port_out) {
>         struct pipeline *p = (struct pipeline *) pipeline;
> 
>         /* Check input arguments */
>         if ((p == NULL) ||
>                 (port_in >= p->n_ports_in) ||
>                 (port_out == NULL))
>                 return -1;
> 
>         *port_out = port_in / p->n_ports_in;
>         return 0;
> }

The f_track function is used in all the pipeline instances. All pipeline instances except passthrough pipeline implements default version of the f_track function. The pipelines such as pass-through allows tracking to be performaned through them becasue of straightforward connections between their input and output ports, while pipelines  like flow-classifications, firewall fails the tracking because of the dependency on the table rule set.

> 1. What is a actual use of this function ?
> Quoting the documentation:
> "In some cases, it is useful for a pipeline instance to get application level
> information related to pipeline connectivity, such as to identify the output
> link (e.g. physical NIC port) where one of its output ports connected, either
> directly or indirectly by traversing other pipeline instances."

This function is implemented as the part of tracking mechanism for identifying the physical nic port where a specific output ports of the routing pipeline are eventually connected. Tracking could involve traversing the other intermediate pipelines before actually getting to physical nic ports. As a result of tracking, routing pipeline can use the real MAC addresses of the network interfaces instead of using hardcoded default value for building the table entries . Furthermore, It also adds support for automatic route updates (add/remove routing entries) when linked physical NIC ports change their state (up/down).

> 2. The 1st condition check remains same in both. But in pass-through
> port_out is assigned some value. what does this mean ?

These are older version of the functions, please check with latest code.

Jasvinder