--------
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.
.. code-block:: console
- ./build/ipv4_multicast -c 0x00f -n 3 -- -p 0x3 -q 1
+ ./build/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
.. 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);
+ packet_pool = rte_pktmbuf_pool_create("packet_pool", NB_PKT_MBUF, 32,
+ 0, PKT_MBUF_DATA_SIZE, rte_socket_id());
+ header_pool = rte_pktmbuf_pool_create("header_pool", NB_HDR_MBUF, 32,
+ 0, HDR_MBUF_DATA_SIZE, rte_socket_id());
+ clone_pool = rte_pktmbuf_pool_create("clone_pool", NB_CLONE_MBUF, 32,
+ 0, 0, rte_socket_id());
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.
/* 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);
+ RTE_ASSERT(iphdr != NULL);
dest_addr = rte_be_to_cpu_32(iphdr->dst_addr);
Then, the packet is checked to see if it has a multicast destination address and
for (n = 0; v != 0; v &= v - 1, n++)
;
- return (n);
+ return n;
}
This is done to determine which forwarding algorithm to use.
.. code-block:: c
- /* construct destination ethernet address */
+ /* construct destination Ethernet address */
dst_eth_addr = ETHER_ADDR_FOR_IPV4_MCAST(dest_addr);
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 ORed
+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
ethdr = (struct ether_hdr *)rte_pktmbuf_prepend(pkt, (uint16_t) sizeof(*ethdr));
- RTE_MBUF_ASSERT(ethdr != NULL);
+ RTE_ASSERT(ethdr != NULL);
ether_addr_copy(dest_addr, ðdr->d_addr);
ether_addr_copy(&ports_eth_addr[port], ðdr->s_addr);
/* Create new mbuf for the header. */
if (unlikely ((hdr = rte_pktmbuf_alloc(header_pool)) == NULL))
- return (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);
+ return NULL;
}
/* prepend new header */
hdr->ol_flags = pkt->ol_flags;
rte_mbuf_sanity_check(hdr, RTE_MBUF_PKT, 1);
- return (hdr);
+ return hdr;
}