DOCA Flow Connection Tracking

This guide provides an overview and configuration instructions for the DOCA Flow Connection Tracking (CT) API.

The DOCA Flow Connection Tracking (CT) module is a 5-tuple table designed to efficiently track network connections using hardware resources. It supports the following key features:

• Track zone and 5-tuple sessions – Track and manage network connections based on a 5-tuple (source IP, destination IP, source port, destination port, and protocol) along with zone-based separation

• Zone-based virtual tables – Enable logical isolation using zones

• Aging support – Remove idle connections automatically using configurable timeouts

• Connection metadata – Set and manage metadata for tracked connections

• Bidirectional packet handling – Manage traffic in both directions of a connection

• High connection rate – Efficiently handle a high rate of connections per second (CPS)

The CT module makes it simple and efficient to track connections by leveraging hardware resources.

The DOCA Flow CT Pipe is designed to handle non-encapsulated TCP and UDP packets. It supports two primary actions:

• Forward to next pipe – For packets that match a known 6-tuple connection (5-tuple + zone)

• Miss to next pipe – For packets without a matching connection entry

The application is responsible for handling packets based on these outcomes.

The DOCA Flow CT API consists of four major components:

• CT module manipulation – Configure and manage resources within the CT module

• CT connection entry manipulation – Add, remove, or update connection entries efficiently

• Callbacks – Handle asynchronous processing results for connection entries

• Pipe and entry statistics – Monitor connection tracking performance using pipe-level and entry-level statistics

These components provide flexible control over connection tracking and monitoring, allowing applications to adapt to various network scenarios effectively.

Aging

Aging time refers to the maximum duration (in seconds) a session can remain active without detecting any packets. If no packets are observed within this period, the session is terminated.

To support aging, a dedicated aging thread is launched. This thread polls and checks counters for all active connections, ensuring that stale sessions are removed efficiently.

Managed Mode

In Managed Mode, the application is responsible for:

• Managing worker threads

• Parsing and handling connection lifecycles

This mode utilizes DOCA Flow CT management APIs for creating and destroying connections.

The CT aging module automatically notifies the application of aged-out connections by invoking callbacks.

Connection Rules and Management

Users have the flexibility to create connection rules with different patterns, metadata (meta), or counters which can be applied separately for each packet direction.

To create rules in stages:

1. Create one rule for a connection using the standard API.

2. Add a second rule for the opposite packet direction using the doca_flow_ct_entry_add_dir() API.

Processing CT Entries

DOCA Flow provides specialized APIs to process CT entries using a dedicated queue:

• doca_flow_entries_process – Processes pipe entries in the queue

• doca_flow_aging_handle – Handles the aging of pipe entries

DPU

To enable DOCA Flow CT on the DPU, perform the following on the Arm:

1. Enable iommu.passthrough in Linux boot commands ( or disable SMMU from the DPU BIOS):

   1. Run:

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      sudo vim /etc/default/grub
              

   2. Set GRUB_CMDLINE_LINUX="iommu.passthrough=1".

   3. Run:

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      sudo update-grub
      sudo reboot
              

2. Configure DPU firmware with LAG_RESOURCE_ALLOCATION=1:

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   sudo mlxconfig -d <device-id> s LAG_RESOURCE_ALLOCATION=1
           

   Info

   Retrieve device-id from the output of the mst status -v command. If, under the MST tab, the value is N/A, run the mst start command.

3. Update /etc/mellanox/mlnx-bf.conf as follows:

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   ALLOW_SHARED_RQ="no"
           

4. Perform power cycle on the host and Arm sides.

5. If working with a single port, set the DPU into e-switch mode:

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   sudo devlink dev eswitch set pci/<pcie-address> mode switchdev
   sudo devlink dev param set pci/<pcie-address> name esw_multiport value false cmode runtime
           

   Info

   Retrieve pcie-address from the output of the mst status -v command.

6. If working with two PF ports, set the DPU into multi-port e-switch mode (for the 2 PCIe devices):

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   sudo devlink dev param set pci/<pcie-address> name esw_multiport value true cmode runtime
           

   Info

   Retrieve pcie-address from the output of the mst status -v command.

7. Define huge pages (see DOCA Flow prerequisites).

ConnectX

To enable DOCA Flow CT on the NVIDIA® ConnectX®, perform the following:

1. Configure firmware with LAG_RESOURCE_ALLOCATION=1:

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   sudo mlxconfig -d <device-id> s LAG_RESOURCE_ALLOCATION=1
           

   Info

   Retrieve device-id from the output of the mst status -v command. If, under the MST tab, the value is N/A, run the mst start command.

2. Perform power cycle.

3. If working with a single port:

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   sudo devlink dev eswitch set pci/<pcie-address> mode switchdev
   sudo devlink dev param set pci/<pcie-address> name esw_multiport value false cmode runtime
           

   Info

   Retrieve pcie-address from the output of the mst status -v command.

4. If working with two PF ports:

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   sudo devlink dev eswitch set pci/<pcie-address0> mode switchdev
   sudo devlink dev eswitch set pci/<pcie-address1> mode switchdev
   sudo devlink dev param set pci/<pcie-address0> name esw_multiport value true cmode runtime
   sudo devlink dev param set pci/<pcie-address1> name esw_multiport value true cmode runtime
           

   Info

   Retrieve pcie-address from the output of the mst status -v command.

5. Define huge pages (see DOCA Flow prerequisites).

DOCA Flow CT supports actions based on meta and NAT operations. Each action can be defined as either shared or non-shared.

Shared Actions

Actions that can be shared between entries. Shared actions are predefined and reused in multiple entries.

The user gets a handle per shared action created and uses this handle as a reference to the action where required.

Shared actions are defined using a control queue (see struct doca_flow_ct_cfg).

Non-shared Actions

Actions provided with their data during entry create/update.

These actions are completely managed by DOCA Flow CT and cannot be reused in multiple flows (i.e., NAT operations).

Action Sets in Pipe Creation

When creating a DOCA Flow CT pipe, users must define action sets, just as they would for any other pipe.

Fields in the CT pipe must be marked as CHANGEABLE during pipe creation. This allows the actual criteria for these fields to be specified later during entry creation.

During entry creation or update, different actions can be specified for each direction, allowing variations in action content and/or action type.

Feature Enable

To enable user actions, configure the following parameters:

• User action templates during DOCA Flow CT pipe creation

• Maximum number of user actions (nb_user_actions on DOCA Flow CT init)

Using Actions in Managed Mode

Init

Configure the following parameters on doca_flow_ct_init():

• nb_ctrl_queues – number of control queues for defining shared actions

• nb_user_actions – maximum number of user actions. Must align to 64. Both shared control queues and non-shared control queues cache action IDs to speed up ID allocation. Each queue may cache a maximum of 1024 IDs. Users must configure the expected number of actions + total queues * 1024. This number cannot exceed the number of actions hardware supports.

Create DOCA Flow CT Pipe

Configure actions sets on doca_flow_pipe_create().

Create Shared Actions

Use doca_flow_ct_actions_add_shared() with one of the control queues.

Shared actions can be added at any time before use.

Add Entry

Entry can be created in one of the following ways:

• Using an action handle of a predefined shared action

• Using action data, which is specific to the flow, not sharable (e.g., for NAT operations)

The entry can have different actions and/or different action types per direction.

Remove Entry

Non-shared actions associated with an entry are implicitly destroyed by DOCA Flow CT.

Shared actions are not destroyed. They can be used by the user until they decide to remove them.

Update Entry

Entry actions can be updated per direction. All combinations of shared/non-shared actions are applicable (e.g., update from shared to non-shared).

DOCA Flow CT allows using a different forward pipe per flow direction.

DOCA Flow CT supports the forward pipe in two levels:

• Pipe level – a single forward pipe defined during DOCA Flow CT pipe creation and used for all entries

• Entry level – forward pipe defined during entry create

• DOCA Flow CT operates in one of the two levels

DOCA CT forward in entry level has the following characteristics:

• Supports only DOCA_FLOW_FWD_PIPE (up to 4 different forward pipes)

• Supports forward pipe per flow direction (both directions can have same/different forward pipe)

• Must set forward pipes on each entry create (no default forward pipe)

Turn on the feature:

1. Create DOCA Flow CT pipe with forward type = DOCA_FLOW_FWD_PIPE and next_pipe = NULL .

2. Call to doca_flow_ct_fwd_register to register forward pipes and get fwd_handles in return.

Using Changeable Forward in Managed Mode

1. Initialize DOCA Flow CT (doca_flow_ct_init​).

2. Register forward pipes (doca_flow_ct_fwd_register​).

   • Define pipes that can be used for forward​

3. Create DOCA Flow CT pipe​ (doca_flow_pipe_create) w ith definition of possible forward pipes.

4. Add entry (doca_flow_ct_add_entry).

   • Set origin and/or reply fwd_handles returned from doca_flow_ct_fwd_register.

5. Update forward for entry direction (doca_flow_ct_update_entry​).

   Note

   Updating forward handle requires setting all other parameters with their previous values.​

For the library API reference, refer to DOCA Flow and CT API documentation in the DOCA Library APIs.

The following sections provide additional details about the library API.

enum doca_flow_ct_flags

DOCA Flow CT configuration optional flags.

enum doca_flow_ct doca_flow_ct_entry_flags

DOCA Flow CT Entry optional flags.

enum doca_flow_ct_rule_opr

Options for handling flows in autonomous mode with shared actions. The decision is taken on the first flow packet.

struct direction_cfg

Managed mode configuration for origin or reply direction.

doca_flow_ct_cfg

DOCA Flow CT configuration manipulation:

            

            
	struct doca_flow_ct_cfg *ct_cfg;
 
	ret = doca_flow_ct_cfg_create(&ct_cfg);
 
	doca_flow_ct_cfg_set_flags(ct_cfg, flags);
	doca_flow_ct_cfg_set_queues(ct_cfg, n_queues);
	doca_flow_ct_cfg_set_connections(ct_cfg, n_v4, n_v6, n_max);
	...
 
	ret = doca_flow_ct_init(ct_cfg);
 
final:
	ret = doca_flow_ct_cfg_destroy(ct_cfg);
        

Where:

doca_flow_ct_cfg_create(struct doca_flow_ct_cfg **cfg)

doca_flow_ct_cfg_destroy(struct doca_flow_ct_cfg *cfg)

doca_flow_ct_cfg_set_flags(struct doca_flow_ct_cfg *cfg, uint32_t flags)

doca_flow_ct_cfg_set_queues(struct doca_flow_ct_cfg *cfg, uint32_t n_queues)

doca_flow_ct_cfg_set_queue_depth(struct doca_flow_ct_cfg *cfg, uint32_t queue_depth);

doca_flow_ct_cfg_set_ctrl_queues(struct doca_flow_ct_cfg *cfg, uint32_t n_ctrl_queues)

doca_flow_ct_cfg_set_user_actions(struct doca_flow_ct_cfg *cfg, uint32_t n_user_actions)

doca_flow_ct_cfg_set_connections(struct doca_flow_ct_cfg *cfg,
                          uint32_t n_ipv4,
                          uint32_t n_ipv6,
                          uint32_t n_total)

doca_flow_ct_cfg_set_max_connections_per_zone(struct doca_flow_ct_cfg *cfg,
                               uint32_t max_connections_per_zone)

doca_flow_ct_cfg_set_counter_asymmetric(struct doca_flow_ct_cfg *cfg, uint32_t n_counter_asymmetric)

doca_flow_ct_cfg_set_entry_private_data_size(struct doca_flow_ct_cfg *cfg, uint32_t entry_priv_data_size)

doca_flow_ct_cfg_set_entry_finalize_cb(struct doca_flow_ct_cfg *cfg,
                            doca_flow_ct_entry_finalize_cb entry_finalize_cb)

doca_flow_ct_cfg_set_status_update_cb(struct doca_flow_ct_cfg *cfg,
                           doca_flow_ct_stats_update_cb stats_update_cb);

doca_flow_ct_cfg_set_aging_core(struct doca_flow_ct_cfg *cfg, uint32_t aging_core)

doca_flow_ct_cfg_set_aging_query_delay(struct doca_flow_ct_cfg *cfg, uint32_t aging_query_delay_s)

doca_flow_ct_cfg_set_aging_plugin_ops(struct doca_flow_ct_cfg *cfg,
                           struct doca_flow_ct_aging_ops *aging_ops)

doca_flow_ct_cfg_set_dup_filter_size(struct doca_flow_ct_cfg *cfg, uint32_t dup_filter_sz)

doca_flow_ct_cfg_set_direction(struct doca_flow_ct_cfg *cfg,
                        bool direction,
                        bool match_inner,
                        struct doca_flow_meta *zone_match_mask,
                        struct doca_flow_meta *meta_modify_mask

struct doca_flow_ct_actions

This structure is used in the following cases:

• For defining shared actions. In this case, action data is provided by the user. The action handle is returned by DOCA Flow CT.

• For defining an entry with actions. The structure can be filled with two options:

  • With action handle of a previously created shared action

  • With non-shared action data

DOCA Flow CT action structure.

            

            
enum doca_flow_resource_type  resource_type;
union {
			   /* Used when creating an entry with a shared action. */
               uint32_t action_handle;
 
               /* Used when creating an entry with non-shared action or when creating a shared action. */
               struct {   
                          uint32_t action_idx;
                          struct doca_flow_meta meta;
                          struct doca_flow_header_l4_port l4_port;
                          union {
                                    struct doca_flow_ct_ip4 ip4;
                                    struct doca_flow_ct_ip6 ip6;
                           };
               } data;
       };
        

Where:

This section describes DOCA Flow CT samples based on the DOCA Flow CT pipe.

The samples illustrate how to use the library API to manage TCP/UDP connections.

Running the Samples

1. Refer to the following documents:

   • DOCA Installation Guide for Linux for details on how to install BlueField-related software.

   • NVIDIA BlueField Platform Software Troubleshooting Guide for any issue you may encounter with the installation, compilation, or execution of DOCA samples.

2. To build a given sample, run the following command. If you downloaded the sample from GitHub, update the path in the first line to reflect the location of the sample file:

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   cd /opt/mellanox/doca/samples/doca_flow/flow_ct_udp
   meson /tmp/build
   ninja -C /tmp/build
           

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   The binary doca_flow_ct_udp is created under /tmp/build/samples/.

3. Sample (e.g., doca_flow_ct_udp ) usage:

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   Usage: doca_<sample_name> [DOCA Flags] [Program Flags]
      
   DOCA Flags:
     -h, --help                              Print a help synopsis
     -v, --version                           Print program version information    
     -l, --log-level                         Set the (numeric) log level for the program <10=DISABLE, 20=CRITICAL, 30=ERROR, 40=WARNING, 50=INFO, 60=DEBUG, 70=TRACE>
     --sdk-log-level                         Set the SDK (numeric) log level for the program <10=DISABLE, 20=CRITICAL, 30=ERROR, 40=WARNING, 50=INFO, 60=DEBUG, 70=TRACE>
     -j, --json <path>                       Parse all command flags from an input json file
       
   Program Flags:
     -p, --pci_addr <PCI-ADDRESS>            PCIe device address
           

4. For additional information per sample, use the -h option:

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   /tmp/build/samples/<sample_name> -h
           

The following is a CLI example for running the samples when port 08:00.0 is configured (multi-port e-switch) as manager port:

            

            
/tmp/build/samples/doca_<sample_name> -- -r pci/08:00.0,pf0vf0 -l 60
        

The following is a CLI example for running the samples when port 08:00.0 is configured (multi-port e-switch) as manager port and 08:00.1 is configured as the representor of the second uplink:

            

            
/tmp/build/samples/doca_<sample_name> -- -r pci/08:00.1 -l 60