1.. SPDX-License-Identifier: BSD-3-Clause 2 Copyright(c) 2010-2014 Intel Corporation. 3 4L3 Forwarding Sample Application 5================================ 6 7The L3 Forwarding application is a simple example of packet processing using 8DPDK to demonstrate usage of poll and event mode packet I/O mechanism. 9The application performs L3 forwarding. 10 11Overview 12-------- 13 14The application demonstrates the use of the hash, LPM and FIB libraries in DPDK 15to implement packet forwarding using poll or event mode PMDs for packet I/O. 16The initialization and run-time paths are very similar to those of the 17:doc:`l2_forward_real_virtual` and :doc:`l2_forward_event`. 18The main difference from the L2 Forwarding sample application is that optionally 19packet can be Rx/Tx from/to eventdev instead of port directly and forwarding 20decision is made based on information read from the input packet. 21 22Eventdev can optionally use S/W or H/W (if supported by platform) scheduler 23implementation for packet I/O based on run time parameters. 24 25The lookup method is hash-based, LPM-based or FIB-based 26and is selected at run time. 27When the selected lookup method is hash-based, 28a hash object is used to emulate the flow classification stage. 29The hash object is used in correlation with a flow table to map each input packet to its flow at runtime. 30 31The hash lookup key is represented by a DiffServ 5-tuple composed of the following fields read from the input packet: 32Source IP Address, Destination IP Address, Protocol, Source Port and Destination Port. 33The ID of the output interface for the input packet is read from the identified flow table entry. 34The set of flows used by the application is statically configured and loaded into the hash at initialization time. 35When the selected lookup method is LPM or FIB based, 36an LPM or FIB object is used to emulate the forwarding stage for IPv4 packets. 37The LPM or FIB object is used as the routing table 38to identify the next hop for each input packet at runtime. 39 40The LPM and FIB lookup keys are represented by the destination IP address field 41read from the input packet. 42The ID of the output interface for the input packet is the next hop 43returned by the LPM or FIB lookup. 44The set of LPM and FIB rules used by the application is statically configured 45and loaded into the LPM or FIB object at initialization time. 46 47In the sample application, hash-based and FIB-based forwarding supports 48both IPv4 and IPv6. 49LPM-based forwarding supports IPv4 only. 50 51Compiling the Application 52------------------------- 53 54To compile the sample application see :doc:`compiling`. 55 56The application is located in the ``l3fwd`` sub-directory. 57 58Running the Application 59----------------------- 60 61The application has a number of command line options:: 62 63 ./dpdk-l3fwd [EAL options] -- -p PORTMASK 64 [-P] 65 [--lookup LOOKUP_METHOD] 66 --config(port,queue,lcore)[,(port,queue,lcore)] 67 [--eth-dest=X,MM:MM:MM:MM:MM:MM] 68 [--enable-jumbo [--max-pkt-len PKTLEN]] 69 [--no-numa] 70 [--hash-entry-num] 71 [--ipv6] 72 [--parse-ptype] 73 [--per-port-pool] 74 [--mode] 75 [--eventq-sched] 76 [--event-eth-rxqs] 77 [-E] 78 [-L] 79 80Where, 81 82* ``-p PORTMASK:`` Hexadecimal bitmask of ports to configure 83 84* ``-P:`` Optional, sets all ports to promiscuous mode so that packets are accepted regardless of the packet's Ethernet MAC destination address. 85 Without this option, only packets with the Ethernet MAC destination address set to the Ethernet address of the port are accepted. 86 87* ``--lookup:`` Optional, select the lookup method. 88 Accepted options: 89 ``em`` (Exact Match), 90 ``lpm`` (Longest Prefix Match), 91 ``fib`` (Forwarding Information Base). 92 Default is ``lpm``. 93 94* ``--config (port,queue,lcore)[,(port,queue,lcore)]:`` Determines which queues from which ports are mapped to which cores. 95 96* ``--eth-dest=X,MM:MM:MM:MM:MM:MM:`` Optional, ethernet destination for port X. 97 98* ``--enable-jumbo:`` Optional, enables jumbo frames. 99 100* ``--max-pkt-len:`` Optional, under the premise of enabling jumbo, maximum packet length in decimal (64-9600). 101 102* ``--no-numa:`` Optional, disables numa awareness. 103 104* ``--hash-entry-num:`` Optional, specifies the hash entry number in hexadecimal to be setup. 105 106* ``--ipv6:`` Optional, set if running ipv6 packets. 107 108* ``--parse-ptype:`` Optional, set to use software to analyze packet type. Without this option, hardware will check the packet type. 109 110* ``--per-port-pool:`` Optional, set to use independent buffer pools per port. Without this option, single buffer pool is used for all ports. 111 112* ``--mode:`` Optional, Packet transfer mode for I/O, poll or eventdev. 113 114* ``--eventq-sched:`` Optional, Event queue synchronization method, Ordered, Atomic or Parallel. Only valid if --mode=eventdev. 115 116* ``--event-eth-rxqs:`` Optional, Number of ethernet RX queues per device. Only valid if --mode=eventdev. 117 118* ``-E:`` Optional, enable exact match, 119 legacy flag, please use ``--lookup=em`` instead. 120 121* ``-L:`` Optional, enable longest prefix match, 122 legacy flag, please use ``--lookup=lpm`` instead. 123 124 125For example, consider a dual processor socket platform with 8 physical cores, where cores 0-7 and 16-23 appear on socket 0, 126while cores 8-15 and 24-31 appear on socket 1. 127 128To enable L3 forwarding between two ports, assuming that both ports are in the same socket, using two cores, cores 1 and 2, 129(which are in the same socket too), use the following command: 130 131.. code-block:: console 132 133 ./<build_dir>/examples/dpdk-l3fwd -l 1,2 -n 4 -- -p 0x3 --config="(0,0,1),(1,0,2)" 134 135In this command: 136 137* The -l option enables cores 1, 2 138 139* The -p option enables ports 0 and 1 140 141* The --config option enables one queue on each port and maps each (port,queue) pair to a specific core. 142 The following table shows the mapping in this example: 143 144+----------+-----------+-----------+-------------------------------------+ 145| **Port** | **Queue** | **lcore** | **Description** | 146| | | | | 147+----------+-----------+-----------+-------------------------------------+ 148| 0 | 0 | 1 | Map queue 0 from port 0 to lcore 1. | 149| | | | | 150+----------+-----------+-----------+-------------------------------------+ 151| 1 | 0 | 2 | Map queue 0 from port 1 to lcore 2. | 152| | | | | 153+----------+-----------+-----------+-------------------------------------+ 154 155To use eventdev mode with sync method **ordered** on above mentioned environment, 156Following is the sample command: 157 158.. code-block:: console 159 160 ./<build_dir>/examples/dpdk-l3fwd -l 0-3 -n 4 -a <event device> -- -p 0x3 --eventq-sched=ordered 161 162or 163 164.. code-block:: console 165 166 ./<build_dir>/examples/dpdk-l3fwd -l 0-3 -n 4 -a <event device> \ 167 -- -p 0x03 --mode=eventdev --eventq-sched=ordered 168 169In this command: 170 171* -a option allows the event device supported by platform. 172 The syntax used to indicate this device may vary based on platform. 173 174* The --mode option defines PMD to be used for packet I/O. 175 176* The --eventq-sched option enables synchronization menthod of event queue so that packets will be scheduled accordingly. 177 178If application uses S/W scheduler, it uses following DPDK services: 179 180* Software scheduler 181* Rx adapter service function 182* Tx adapter service function 183 184Application needs service cores to run above mentioned services. Service cores 185must be provided as EAL parameters along with the --vdev=event_sw0 to enable S/W 186scheduler. Following is the sample command: 187 188.. code-block:: console 189 190 ./<build_dir>/examples/dpdk-l3fwd -l 0-7 -s 0xf0000 -n 4 --vdev event_sw0 -- -p 0x3 --mode=eventdev --eventq-sched=ordered 191 192In case of eventdev mode, *--config* option is not used for ethernet port 193configuration. Instead each ethernet port will be configured with mentioned 194setup: 195 196* Single Rx/Tx queue 197 198* Each Rx queue will be connected to event queue via Rx adapter. 199 200* Each Tx queue will be connected via Tx adapter. 201 202Refer to the *DPDK Getting Started Guide* for general information on running applications and 203the Environment Abstraction Layer (EAL) options. 204 205.. _l3_fwd_explanation: 206 207Explanation 208----------- 209 210The following sections provide some explanation of the sample application code. As mentioned in the overview section, 211the initialization and run-time paths are very similar to those of the :doc:`l2_forward_real_virtual` and :doc:`l2_forward_event`. 212The following sections describe aspects that are specific to the L3 Forwarding sample application. 213 214Hash Initialization 215~~~~~~~~~~~~~~~~~~~ 216 217The hash object is created and loaded with the pre-configured entries read from a global array, 218and then generate the expected 5-tuple as key to keep consistence with those of real flow 219for the convenience to execute hash performance test on 4M/8M/16M flows. 220 221.. note:: 222 223 The Hash initialization will setup both ipv4 and ipv6 hash table, 224 and populate the either table depending on the value of variable ipv6. 225 To support the hash performance test with up to 8M single direction flows/16M bi-direction flows, 226 populate_ipv4_many_flow_into_table() function will populate the hash table with specified hash table entry number(default 4M). 227 228.. note:: 229 230 Value of global variable ipv6 can be specified with --ipv6 in the command line. 231 Value of global variable hash_entry_number, 232 which is used to specify the total hash entry number for all used ports in hash performance test, 233 can be specified with --hash-entry-num VALUE in command line, being its default value 4. 234 235.. code-block:: c 236 237 #if (APP_LOOKUP_METHOD == APP_LOOKUP_EXACT_MATCH) 238 239 static void 240 setup_hash(int socketid) 241 { 242 // ... 243 244 if (hash_entry_number != HASH_ENTRY_NUMBER_DEFAULT) { 245 if (ipv6 == 0) { 246 /* populate the ipv4 hash */ 247 populate_ipv4_many_flow_into_table(ipv4_l3fwd_lookup_struct[socketid], hash_entry_number); 248 } else { 249 /* populate the ipv6 hash */ 250 populate_ipv6_many_flow_into_table( ipv6_l3fwd_lookup_struct[socketid], hash_entry_number); 251 } 252 } else 253 if (ipv6 == 0) { 254 /* populate the ipv4 hash */ 255 populate_ipv4_few_flow_into_table(ipv4_l3fwd_lookup_struct[socketid]); 256 } else { 257 /* populate the ipv6 hash */ 258 populate_ipv6_few_flow_into_table(ipv6_l3fwd_lookup_struct[socketid]); 259 } 260 } 261 } 262 #endif 263 264LPM Initialization 265~~~~~~~~~~~~~~~~~~ 266 267The LPM object is created and loaded with the pre-configured entries read from a global array. 268 269.. literalinclude:: ../../../examples/l3fwd/l3fwd_em.c 270 :language: c 271 :start-after: Initialize exact match (hash) parameters. 8< 272 :end-before: >8 End of initialization of hash parameters. 273 274FIB Initialization 275~~~~~~~~~~~~~~~~~~ 276 277The FIB object is created and loaded with the pre-configured entries 278read from a global array. 279The abridged code snippet below shows the FIB initialization for IPv4, 280the full setup function including the IPv6 setup can be seen in the app code. 281 282.. literalinclude:: ../../../examples/l3fwd/l3fwd_fib.c 283 :language: c 284 :start-after: Function to setup fib. 8< 285 :end-before: >8 End of setup fib. 286 287Packet Forwarding for Hash-based Lookups 288~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 289 290For each input packet, the packet forwarding operation is done by the l3fwd_simple_forward() 291or simple_ipv4_fwd_4pkts() function for IPv4 packets or the simple_ipv6_fwd_4pkts() function for IPv6 packets. 292The l3fwd_simple_forward() function provides the basic functionality for both IPv4 and IPv6 packet forwarding 293for any number of burst packets received, 294and the packet forwarding decision (that is, the identification of the output interface for the packet) 295for hash-based lookups is done by the get_ipv4_dst_port() or get_ipv6_dst_port() function. 296The get_ipv4_dst_port() function is shown below: 297 298.. literalinclude:: ../../../examples/l3fwd/l3fwd_em.c 299 :language: c 300 :start-after: Performing hash-based lookups. 8< 301 :end-before: >8 End of performing hash-based lookups. 302 303The get_ipv6_dst_port() function is similar to the get_ipv4_dst_port() function. 304 305The simple_ipv4_fwd_4pkts() and simple_ipv6_fwd_4pkts() function are optimized for continuous 4 valid ipv4 and ipv6 packets, 306they leverage the multiple buffer optimization to boost the performance of forwarding packets with the exact match on hash table. 307The key code snippet of simple_ipv4_fwd_4pkts() is shown below: 308 309.. code-block:: c 310 311 static inline void 312 simple_ipv4_fwd_4pkts(struct rte_mbuf* m[4], uint16_t portid, struct lcore_conf *qconf) 313 { 314 // ... 315 316 data[0] = _mm_loadu_si128(( m128i*)(rte_pktmbuf_mtod(m[0], unsigned char *) + sizeof(struct rte_ether_hdr) + offsetof(struct rte_ipv4_hdr, time_to_live))); 317 data[1] = _mm_loadu_si128(( m128i*)(rte_pktmbuf_mtod(m[1], unsigned char *) + sizeof(struct rte_ether_hdr) + offsetof(struct rte_ipv4_hdr, time_to_live))); 318 data[2] = _mm_loadu_si128(( m128i*)(rte_pktmbuf_mtod(m[2], unsigned char *) + sizeof(struct rte_ether_hdr) + offsetof(struct rte_ipv4_hdr, time_to_live))); 319 data[3] = _mm_loadu_si128(( m128i*)(rte_pktmbuf_mtod(m[3], unsigned char *) + sizeof(struct rte_ether_hdr) + offsetof(struct rte_ipv4_hdr, time_to_live))); 320 321 key[0].xmm = _mm_and_si128(data[0], mask0); 322 key[1].xmm = _mm_and_si128(data[1], mask0); 323 key[2].xmm = _mm_and_si128(data[2], mask0); 324 key[3].xmm = _mm_and_si128(data[3], mask0); 325 326 const void *key_array[4] = {&key[0], &key[1], &key[2],&key[3]}; 327 328 rte_hash_lookup_bulk(qconf->ipv4_lookup_struct, &key_array[0], 4, ret); 329 330 dst_port[0] = (ret[0] < 0)? portid:ipv4_l3fwd_out_if[ret[0]]; 331 dst_port[1] = (ret[1] < 0)? portid:ipv4_l3fwd_out_if[ret[1]]; 332 dst_port[2] = (ret[2] < 0)? portid:ipv4_l3fwd_out_if[ret[2]]; 333 dst_port[3] = (ret[3] < 0)? portid:ipv4_l3fwd_out_if[ret[3]]; 334 335 // ... 336 } 337 338The simple_ipv6_fwd_4pkts() function is similar to the simple_ipv4_fwd_4pkts() function. 339 340Known issue: IP packets with extensions or IP packets which are not TCP/UDP cannot work well at this mode. 341 342Packet Forwarding for LPM-based Lookups 343~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 344 345For each input packet, the packet forwarding operation is done by the l3fwd_simple_forward() function, 346but the packet forwarding decision (that is, the identification of the output interface for the packet) 347for LPM-based lookups is done by the get_ipv4_dst_port() function below: 348 349.. literalinclude:: ../../../examples/l3fwd/l3fwd_lpm.c 350 :language: c 351 :start-after: Performing LPM-based lookups. 8< 352 :end-before: >8 End of performing LPM-based lookups. 353 354Packet Forwarding for FIB-based Lookups 355~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 356 357The FIB library was designed to process multiple packets at once, 358it does not have separate functions for single and bulk lookups. 359``rte_fib_lookup_bulk`` is used for IPv4 lookups 360and ``rte_fib6_lookup_bulk`` for IPv6. 361Various examples of these functions being used 362can be found in the sample app code. 363 364Eventdev Driver Initialization 365~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 366Eventdev driver initialization is same as L2 forwarding eventdev application. 367Refer :doc:`l2_forward_event` for more details. 368