doc: clarify usage of netvsc PMD

[dpdk.git] / doc / guides / nics / pcap_ring.rst

diff --git a/doc/guides/nics/pcap_ring.rst b/doc/guides/nics/pcap_ring.rst
index de47f68..879e543 100644 (file)
--- a/doc/guides/nics/pcap_ring.rst
+++ b/doc/guides/nics/pcap_ring.rst
@@ -5,7 +5,7 @@ Libpcap and Ring Based Poll Mode Drivers
 ========================================
 
 In addition to Poll Mode Drivers (PMDs) for physical and virtual hardware,
-the DPDK also includes two pure-software PMDs. These two drivers are:
+the DPDK also includes pure-software PMDs, two of these drivers are:
 
 *   A libpcap -based PMD (librte_pmd_pcap) that reads and writes packets using libpcap,
     - both from files on disk, as well as from physical NIC devices using standard Linux kernel drivers.
@@ -71,11 +71,19 @@ The different stream types are:
         tx_pcap=/path/to/file.pcap
 
 *   rx_iface: Defines a reception stream based on a network interface name.
-    The driver reads packets coming from the given interface using the Linux kernel driver for that interface.
+    The driver reads packets from the given interface using the Linux kernel driver for that interface.
+    The driver captures both the incoming and outgoing packets on that interface.
     The value is an interface name.
 
         rx_iface=eth0
 
+*   rx_iface_in: Defines a reception stream based on a network interface name.
+    The driver reads packets from the given interface using the Linux kernel driver for that interface.
+    The driver captures only the incoming packets on that interface.
+    The value is an interface name.
+
+        rx_iface_in=eth0
+
 *   tx_iface: Defines a transmission stream based on a network interface name.
     The driver sends packets to the given interface using the Linux kernel driver for that interface.
     The value is an interface name.
@@ -122,6 +130,21 @@ Forward packets through two network interfaces:
     $RTE_TARGET/app/testpmd -l 0-3 -n 4 \
         --vdev 'net_pcap0,iface=eth0' --vdev='net_pcap1;iface=eth1'
 
+Enable 2 tx queues on a network interface:
+
+.. code-block:: console
+
+    $RTE_TARGET/app/testpmd -l 0-3 -n 4 \
+        --vdev 'net_pcap0,rx_iface=eth1,tx_iface=eth1,tx_iface=eth1' \
+        -- --txq 2
+
+Read only incoming packets from a network interface and write them back to the same network interface:
+
+.. code-block:: console
+
+    $RTE_TARGET/app/testpmd -l 0-3 -n 4 \
+        --vdev 'net_pcap0,rx_iface_in=eth1,tx_iface=eth1'
+
 Using libpcap-based PMD with the testpmd Application
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
@@ -148,6 +171,12 @@ Otherwise, the first 512 packets from the input pcap file will be discarded by t
         --vdev 'net_pcap0,rx_pcap=file_rx.pcap,tx_pcap=file_tx.pcap' \
         -- --port-topology=chained --no-flush-rx
 
+.. note::
+
+   The network interface provided to the PMD should be up. The PMD will return
+   an error if interface is down, and the PMD itself won't change the status
+   of the external network interface.
+
 
 Rings-based PMD
 ~~~~~~~~~~~~~~~