-.. BSD LICENSE
- Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
- All rights reserved.
-
- Redistribution and use in source and binary forms, with or without
- modification, are permitted provided that the following conditions
- are met:
-
- * Redistributions of source code must retain the above copyright
- notice, this list of conditions and the following disclaimer.
- * Redistributions in binary form must reproduce the above copyright
- notice, this list of conditions and the following disclaimer in
- the documentation and/or other materials provided with the
- distribution.
- * Neither the name of Intel Corporation nor the names of its
- contributors may be used to endorse or promote products derived
- from this software without specific prior written permission.
-
- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+.. SPDX-License-Identifier: BSD-3-Clause
+ Copyright(c) 2010-2014 Intel Corporation.
IPv4 Multicast Sample Application
=================================
--------
The application demonstrates the use of zero-copy buffers for packet forwarding.
-The initialization and run-time paths are very similar to those of the L2 forwarding application
-(see Chapter 9 "L2 Forwarding Sample Application (in Real and Virtualized Environments)" for details more information).
+The initialization and run-time paths are very similar to those of the :doc:`l2_forward_real_virtual`.
This guide highlights the differences between the two applications.
There are two key differences from the L2 Forwarding sample application:
The lookup table is composed of pairs of destination IPv4 address (the FBK)
and a port mask associated with that IPv4 address.
+.. note::
+
+ The max port mask supported in the given hash table is 0xf, so only first
+ four ports can be supported.
+ If using non-consecutive ports, use the destination IPv4 address accordingly.
+
For convenience and simplicity, this sample application does not take IANA-assigned multicast addresses into account,
but instead equates the last four bytes of the multicast group (that is, the last four bytes of the destination IP address)
with the mask of ports to multicast packets to.
Also, the application does not consider the Ethernet addresses;
it looks only at the IPv4 destination address for any given packet.
-Building the Application
-------------------------
-
-To compile the application:
-
-#. Go to the sample application directory:
-
- .. code-block:: console
-
- export RTE_SDK=/path/to/rte_sdk
- cd ${RTE_SDK}/examples/ipv4_multicast
+Compiling the Application
+-------------------------
-#. Set the target (a default target is used if not specified). For example:
+To compile the sample application see :doc:`compiling`.
- .. code-block:: console
-
- export RTE_TARGET=x86_64-native-linuxapp-gcc
-
-See the *DPDK Getting Started Guide* for possible RTE_TARGET values.
-
-#. Build the application:
-
- .. code-block:: console
-
- make
-
-.. note::
-
- The compiled application is written to the build subdirectory.
- To have the application written to a different location,
- the O=/path/to/build/directory option may be specified in the make command.
+The application is located in the ``ipv4_multicast`` sub-directory.
Running the Application
-----------------------
.. code-block:: console
- ./build/ipv4_multicast [EAL options] -- -p PORTMASK [-q NQ]
+ ./<build_dir>/examples/dpdk-ipv4_multicast [EAL options] -- -p PORTMASK [-q NQ]
where,
.. code-block:: console
- ./build/ipv4_multicast -c 0x00f -n 3 -- -p 0x3 -q 1
+ ./<build_dir>/examples/dpdk-ipv4_multicast -l 0-3 -n 3 -- -p 0x3 -q 1
In this command:
-* The -c option enables cores 0, 1, 2 and 3
+* The -l option enables cores 0, 1, 2 and 3
* The -n option specifies 3 memory channels
The following sections provide some explanation of the code.
As mentioned in the overview section,
-the initialization and run-time paths are very similar to those of the L2 Forwarding sample application
-(see Chapter 9 "L2 Forwarding Sample Application in Real and Virtualized Environments" for more information).
+the initialization and run-time paths are very similar to those of the :doc:`l2_forward_real_virtual`.
The following sections describe aspects that are specific to the IPv4 Multicast sample application.
Memory Pool Initialization
Two of the pools are for indirect buffers used for packet duplication purposes.
Memory pools for indirect buffers are initialized differently from the memory pool for direct buffers:
-.. code-block:: c
-
- packet_pool = rte_mempool_create("packet_pool", NB_PKT_MBUF, PKT_MBUF_SIZE, 32, sizeof(struct rte_pktmbuf_pool_private),
- rte_pktmbuf_pool_init, NULL, rte_pktmbuf_init, NULL, rte_socket_id(), 0);
-
- header_pool = rte_mempool_create("header_pool", NB_HDR_MBUF, HDR_MBUF_SIZE, 32, 0, NULL, NULL, rte_pktmbuf_init, NULL, rte_socket_id(), 0);
- clone_pool = rte_mempool_create("clone_pool", NB_CLONE_MBUF,
- CLONE_MBUF_SIZE, 32, 0, NULL, NULL, rte_pktmbuf_init, NULL, rte_socket_id(), 0);
+.. literalinclude:: ../../../examples/ipv4_multicast/main.c
+ :language: c
+ :start-after: Create the mbuf pools. 8<
+ :end-before: >8 End of create mbuf pools.
+ :dedent: 1
The reason for this is because indirect buffers are not supposed to hold any packet data and
therefore can be initialized with lower amount of reserved memory for each buffer.
The hash object is created and loaded with the pre-configured entries read from a global array:
-.. code-block:: c
-
- static int
-
- init_mcast_hash(void)
- {
- uint32_t i;
- mcast_hash_params.socket_id = rte_socket_id();
-
- mcast_hash = rte_fbk_hash_create(&mcast_hash_params);
- if (mcast_hash == NULL){
- return -1;
- }
-
- for (i = 0; i < N_MCAST_GROUPS; i ++){
- if (rte_fbk_hash_add_key(mcast_hash, mcast_group_table[i].ip, mcast_group_table[i].port_mask) < 0) {
- return -1;
- }
- }
- return 0;
- }
+.. literalinclude:: ../../../examples/ipv4_multicast/main.c
+ :language: c
+ :start-after: Hash object is created and loaded. 8<
+ :end-before: >8 End of hash object is created and loaded.
Forwarding
~~~~~~~~~~
All forwarding is done inside the mcast_forward() function.
Firstly, the Ethernet* header is removed from the packet and the IPv4 address is extracted from the IPv4 header:
-.. code-block:: c
-
- /* Remove the Ethernet header from the input packet */
-
- iphdr = (struct ipv4_hdr *)rte_pktmbuf_adj(m, sizeof(struct ether_hdr));
- RTE_MBUF_ASSERT(iphdr != NULL);
- dest_addr = rte_be_to_cpu_32(iphdr->dst_addr);
+.. literalinclude:: ../../../examples/ipv4_multicast/main.c
+ :language: c
+ :start-after: Remove the Ethernet header from the input packet. 8<
+ :end-before: >8 End of removing the Ethernet header from the input packet.
+ :dedent: 1
Then, the packet is checked to see if it has a multicast destination address and
if the routing table has any ports assigned to the destination address:
-.. code-block:: c
-
- if (!IS_IPV4_MCAST(dest_addr) ||
- (hash = rte_fbk_hash_lookup(mcast_hash, dest_addr)) <= 0 ||
- (port_mask = hash & enabled_port_mask) == 0) {
- rte_pktmbuf_free(m);
- return;
- }
+.. literalinclude:: ../../../examples/ipv4_multicast/main.c
+ :language: c
+ :start-after: Check valid multicast address. 8<
+ :end-before: >8 End of valid multicast address check.
+ :dedent: 1
Then, the number of ports in the destination portmask is calculated with the help of the bitcnt() function:
-.. code-block:: c
-
- /* Get number of bits set. */
-
- static inline uint32_t bitcnt(uint32_t v)
- {
- uint32_t n;
-
- for (n = 0; v != 0; v &= v - 1, n++)
- ;
- return n;
- }
+.. literalinclude:: ../../../examples/ipv4_multicast/main.c
+ :language: c
+ :start-after: Get number of bits set. 8<
+ :end-before: >8 End of getting number of bits set.
This is done to determine which forwarding algorithm to use.
This is explained in more detail in the next section.
Thereafter, a destination Ethernet address is constructed:
-.. code-block:: c
-
- /* construct destination Ethernet address */
-
- dst_eth_addr = ETHER_ADDR_FOR_IPV4_MCAST(dest_addr);
+.. literalinclude:: ../../../examples/ipv4_multicast/main.c
+ :language: c
+ :start-after: Construct destination ethernet address. 8<
+ :end-before: >8 End of constructing destination ethernet address.
+ :dedent: 1
Since Ethernet addresses are also part of the multicast process, each outgoing packet carries the same destination Ethernet address.
The destination Ethernet address is constructed from the lower 23 bits of the multicast group OR-ed
with the Ethernet address 01:00:5e:00:00:00, as per RFC 1112:
-.. code-block:: c
-
- #define ETHER_ADDR_FOR_IPV4_MCAST(x) \
- (rte_cpu_to_be_64(0x01005e000000ULL | ((x) & 0x7fffff)) >> 16)
+.. literalinclude:: ../../../examples/ipv4_multicast/main.c
+ :language: c
+ :start-after: Construct Ethernet multicast address from IPv4 multicast Address. 8<
+ :end-before: >8 End of Construction of multicast address from IPv4 multicast address.
Then, packets are dispatched to the destination ports according to the portmask associated with a multicast group:
-.. code-block:: c
-
- for (port = 0; use_clone != port_mask; port_mask >>= 1, port++) {
- /* Prepare output packet and send it out. */
-
- if ((port_mask & 1) != 0) {
- if (likely ((mc = mcast_out_pkt(m, use_clone)) != NULL))
- mcast_send_pkt(mc, &dst_eth_addr.as_addr, qconf, port);
- else if (use_clone == 0)
- rte_pktmbuf_free(m);
- }
- }
+.. literalinclude:: ../../../examples/ipv4_multicast/main.c
+ :language: c
+ :start-after: Packets dispatched to destination ports. 8<
+ :end-before: >8 End of packets dispatched to destination ports.
+ :dedent: 1
The actual packet transmission is done in the mcast_send_pkt() function:
-.. code-block:: c
-
- static inline void mcast_send_pkt(struct rte_mbuf *pkt, struct ether_addr *dest_addr, struct lcore_queue_conf *qconf, uint8_t port)
- {
- struct ether_hdr *ethdr;
- uint16_t len;
-
- /* Construct Ethernet header. */
-
- ethdr = (struct ether_hdr *)rte_pktmbuf_prepend(pkt, (uint16_t) sizeof(*ethdr));
-
- RTE_MBUF_ASSERT(ethdr != NULL);
-
- ether_addr_copy(dest_addr, ðdr->d_addr);
- ether_addr_copy(&ports_eth_addr[port], ðdr->s_addr);
- ethdr->ether_type = rte_be_to_cpu_16(ETHER_TYPE_IPv4);
-
- /* Put new packet into the output queue */
-
- len = qconf->tx_mbufs[port].len;
- qconf->tx_mbufs[port].m_table[len] = pkt;
- qconf->tx_mbufs[port].len = ++len;
-
- /* Transmit packets */
-
- if (unlikely(MAX_PKT_BURST == len))
- send_burst(qconf, port);
- }
+.. literalinclude:: ../../../examples/ipv4_multicast/main.c
+ :language: c
+ :start-after: Write new Ethernet header to outgoing packets. 8<
+ :end-before: >8 End of writing new Ethernet headers.
Buffer Cloning
~~~~~~~~~~~~~~
Depending on the number of segments or the number of ports in the outgoing portmask,
either the first (with cloning) or the second (without cloning) approach is taken:
-.. code-block:: c
-
- use_clone = (port_num <= MCAST_CLONE_PORTS && m->pkt.nb_segs <= MCAST_CLONE_SEGS);
+.. literalinclude:: ../../../examples/ipv4_multicast/main.c
+ :language: c
+ :start-after: Should we use rte_pktmbuf_clone() or not. 8<
+ :end-before: >8 End of using rte_pktmbuf_clone().
+ :dedent: 1
It is the mcast_out_pkt() function that performs the packet duplication (either with or without actually cloning the buffers):
-.. code-block:: c
-
- static inline struct rte_mbuf *mcast_out_pkt(struct rte_mbuf *pkt, int use_clone)
- {
- struct rte_mbuf *hdr;
-
- /* Create new mbuf for the header. */
-
- if (unlikely ((hdr = rte_pktmbuf_alloc(header_pool)) == NULL))
- return NULL;
-
- /* If requested, then make a new clone packet. */
-
- if (use_clone != 0 && unlikely ((pkt = rte_pktmbuf_clone(pkt, clone_pool)) == NULL)) {
- rte_pktmbuf_free(hdr);
- return NULL;
- }
-
- /* prepend new header */
-
- hdr->pkt.next = pkt;
-
- /* update header's fields */
-
- hdr->pkt.pkt_len = (uint16_t)(hdr->pkt.data_len + pkt->pkt.pkt_len);
- hdr->pkt.nb_segs = (uint8_t)(pkt->pkt.nb_segs + 1);
-
- /* copy metadata from source packet */
-
- hdr->pkt.in_port = pkt->pkt.in_port;
- hdr->pkt.vlan_macip = pkt->pkt.vlan_macip;
- hdr->pkt.hash = pkt->pkt.hash;
- hdr->ol_flags = pkt->ol_flags;
- rte_mbuf_sanity_check(hdr, RTE_MBUF_PKT, 1);
-
- return hdr;
- }
+.. literalinclude:: ../../../examples/ipv4_multicast/main.c
+ :language: c
+ :start-after: mcast_out_pkt 8<
+ :end-before: >8 End of mcast_out_kt.
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