[spp] [PATCH 2/6] docs: add spp_pcap into document of overview

[x-fn-spp@sl.ntt-tx.co.jp]

From: Hideyuki Yamashita <yamashita.hideyuki@po.ntt-tx.co.jp>

Add spp_pcap into document of overview.

Signed-off-by: Hideyuki Yamashita <yamashita.hideyuki@po.ntt-tx.co.jp>
Signed-off-by: Naoki Takada <takada.naoki@lab.ntt.co.jp>
---
 docs/guides/spp_vf/overview.rst | 34 ++++++++++++++++++++++++++++++---
 1 file changed, 31 insertions(+), 3 deletions(-)

diff --git a/docs/guides/spp_vf/overview.rst b/docs/guides/spp_vf/overview.rst
index 446beb0..09c21af 100644
--- a/docs/guides/spp_vf/overview.rst
+++ b/docs/guides/spp_vf/overview.rst
@@ -1,13 +1,12 @@
 ..  SPDX-License-Identifier: BSD-3-Clause
-    Copyright(c) 2010-2014 Intel Corporation
+    Copyright(c) 2019 Nippon Telegraph and Telephone Corporation
 
 .. _spp_vf_overview:
 
 Overview
 ========
 
-This section describes an overview of SPP's extensions, ``spp_vf`` and
-``spp_mirror``.
+This section describes an overview of SPP's extensions, ``spp_vf`` , ``spp_mirror`` and ``spp_pcap``.
 SPP provides a connectivity between DPDK processes as a virtual patch panel.
 However, It is not sufficient considering more practical usecases.
 For instance, you might need a classification for incoming packets if you have
@@ -24,6 +23,8 @@ packets. This feature is intended to use as a
 <https://docs.openstack.org/dragonflow/latest/specs/tap_as_a_service.html>`_
 feature for port mirroring introduced in OpenStack.
 
+``spp_pcap`` is an another kind of secondary process to capture incoming packets. This feature is intended to capture up to 10Gbps packets.
+
 
 spp_vf
 ------
@@ -77,3 +78,30 @@ destination and a monitor application running on VM3.
    :width: 70%
 
    Overview of spp_mirror
+
+
+spp_pcap
+--------
+
+This section describes an overview of SPP's extensions, ``spp_pcap``.
+SPP provides a connectivity between VM and NIC as a virtual patch panel.
+However, for more practical use, operator and/or developer needs to capture
+packets. For such use, spp_pcap provides packet capturing feature from
+specific port. It is aimed to capture up to 10Gbps packets.
+
+``spp_pcap`` is a SPP secondary process for capturing packets from specific
+``port``. :numref:`figure_spp_pcap_overview` shows an overview of use of
+``spp_pcap`` in which ``spp_pcap`` process receives packets from ``phy:0``
+for capturing.
+
+``spp_pcap`` provides packet capturing capability as a SPP secondary process.
+``spp_pcap`` has one manager thread like spp_vf, and has two types of worker
+threads unlike spp_vf.
+
+
+.. _figure_spp_pcap_overview:
+
+.. figure:: ../images/spp_pcap/spp_pcap_overview.*
+   :width: 55%
+
+   Overview of spp_pcap
-- 
2.17.1