net/enic: add devarg to specify ingress VLAN rewrite mode

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

diff --git a/doc/guides/nics/enic.rst b/doc/guides/nics/enic.rst
index d650ba0..7764c86 100644 (file)
--- a/doc/guides/nics/enic.rst
+++ b/doc/guides/nics/enic.rst
@@ -351,9 +351,10 @@ Limitations
   In test setups where an Ethernet port of a Cisco adapter in TRUNK mode is
   connected point-to-point to another adapter port or connected though a router
   instead of a switch, all ingress packets will be VLAN tagged. Programs such
-  as l3fwd which do not account for VLAN tags in packets will misbehave. The
-  solution is to enable VLAN stripping on ingress. The following code fragment is
-  an example of how to accomplish this:
+  as l3fwd may not account for VLAN tags in packets and may misbehave. One
+  solution is to enable VLAN stripping on ingress so the VLAN tag is removed
+  from the packet and put into the mbuf->vlan_tci field. Here is an example
+  of how to accomplish this:
 
 .. code-block:: console
 
@@ -361,6 +362,14 @@ Limitations
      vlan_offload |= ETH_VLAN_STRIP_OFFLOAD;
      rte_eth_dev_set_vlan_offload(port, vlan_offload);
 
+Another alternative is modify the adapter's ingress VLAN rewrite mode so that
+packets with the default VLAN tag are stripped by the adapter and presented to
+DPDK as untagged packets. In this case mbuf->vlan_tci and the PKT_RX_VLAN and
+PKT_RX_VLAN_STRIPPED mbuf flags would not be set. This mode is enabled with the
+``devargs`` parameter ``ig-vlan-rewrite=1``. For example::
+
+    -w 12:00.0,ig-vlan-rewrite=1
+
 - Limited flow director support on 1200 series and 1300 series Cisco VIC
   adapters with old firmware. Please see :ref:`enic-flow-director`.