Range Matching

The range matching is supported using the template API. When creating a pattern template, the common bits of “mask” and “last” in the "struct rte_flow_item" are used to specify the fields that will be used in range matching. When inserting a rule with such pattern template, the “spec” in "struct rte_flow_item" is used to set the lower boundary and “last” is used as the upper boundary of a range. More than one fields of range matching can be supported in a single pattern template, and the bits only present in the “mask” are still treated as exact matching.

The supported items are IPv4 packet length, IPv4 destination address, IPv4 source address, IPv4 version and header length, IPv4 time to live, IPv6 hop limit, IPv6 payload length, UDP/TCP source port, UDP/TCP destination port, TCP flags, tag, and metadata.

With the IP length range matching, the user can redirect the packets with length > X to the slow path and handled in the software. In the meanwhile, other packets can be fully offloaded without any software participation.

For example, in a virtual environment in which network application vendors does not have full control on the network configuration, tenants can decide on MTU size and the network application should accommodate to it. Offloaded encapsulation actions are adding the tunnel header to a packet. To avoid a situation in which a packet size exceeds the MTU size, after its encapsulation (and later on dropped), the DPDK application can set a rule to check for the IP length, ensuring that it does not exceed a specified length. If it does, it can be redirected to slow path (DPDK application) for proper handling (e.g. split to multiple packets), otherwise, it can be treated in the hardware.

Currently, the complex actions cannot be supported with range matching, the terminate actions can be supported.

• QUEUE, RSS, PORT_ID, REPRESENTED_PORT, JUMP, DROP

• To create the pattern template with IPv4 length range matching specified

  Copy

  Copied!

              
  
              
  flow pattern_template 0 create ingress relaxed no pattern_template_id 1 template eth / ipv4 length mask 0xffff length last 0xffff / end
          

• To create the action template with count and jump actions

  Copy

  Copied!

              
  
              
  flow actions_template 0 create ingress actions_template_id 1 template count / jump / end mask count / jump / end
          

• To create the template table

  Copy

  Copied!

              
  
              
  flow template_table 0 create group 1 priority 0 ingress table_id 0x11 pattern_template 1 actions_template 1 rules_number 128
          

• To insert a rule to match the length between 70 to 500 bytes

  Copy

  Copied!

              
  
              
  flow queue 0 create 2 template_table 0x11 pattern_template 0 actions_template 0 postpone no pattern eth / ipv4 length spec 70 length last 500 / end actions count / jump group 2 / end
  flow pull 0 queue 2
  …
          

• To insert another rule to match the length between 1500 to 4000 bytes

  Copy

  Copied!

              
  
              
  flow queue 0 create 2 template_table 0x11 pattern_template 0 actions_template 0 postpone no pattern eth / ipv4 length spec 1500 length last 4000 / end actions count / jump group 3 / end
  flow pull 0 queue 2
  …
          

Refer to the “Template API” section for the usage of the functions and steps.

            

            
struct rte_flow_item_ipv4 pt_ip = {
	.hdr.total_length = 0xffff,
};
struct rte_flow_item patterns[] = {
    {
		.type = RTE_FLOW_ITEM_TYPE_ETH,
    },
    {
		.type = RTE_FLOW_ITEM_TYPE_IPV4,
		.mask = &pt_ip,
		.last = &pt_ip,
	},
   	{
		.type = RTE_FLOW_ITEM_TYPE_END,
	},
};
 
struct rte_flow_item_ipv4 len_start = {
	.hdr.total_length = RTE_BE16(70),
};
struct rte_flow_item_ipv4 len_end = {
	.hdr.total_length = RTE_BE16(500),
};
struct rte_flow_item rule_items[] = {
    {
		.type = RTE_FLOW_ITEM_TYPE_ETH,
    },
    {
		.type = RTE_FLOW_ITEM_TYPE_IPV4,
		.mask = &len_start,
		.last = &len_end,
    },
	{
		.type = RTE_FLOW_ITEM_TYPE_END,
	},
};
struct rte_flow_pattern_template *pts[1] = {NULL};
…
pt = rte_flow_pattern_template_create(port_id, &pt_attr, patterns, &error);
…
pts[0] = pt1;
…
range_flow_1 = rte_flow_async_create(port_id, queue_id, &attr, tbl,
                               rule_times, 0, actions, 0,
                               NULL, &error);