helper+docs+examples: New helper to simplify link failing
Thanks to Saran Tarnoi for providing base implementation of the code
diff --git a/helper/ndn-link-control-helper.h b/helper/ndn-link-control-helper.h
new file mode 100644
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+++ b/helper/ndn-link-control-helper.h
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+/* -*- Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2013 University of California, Los Angeles
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation;
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Author: Alexander Afanasyev <alexander.afanasyev@ucla.edu>
+ * : Saran Tarnoi <saran.tarnoi@gmail.com>
+ */
+
+#ifndef NDN_LINK_CONTROL_HELPER_H
+#define NDN_LINK_CONTROL_HELPER_H
+
+#include "ns3/ptr.h"
+#include "ns3/node.h"
+
+namespace ns3 {
+namespace ndn {
+
+/**
+ * @brief Helper class to control the up or down statuss of an NDN link connecting two specific nodes
+ * @ingroup Ndn
+ */
+class LinkControlHelper
+{
+public:
+ /**
+ * @brief Fail NDN link between two nodes
+ *
+ * The helper will attempt to find NDN link between node1 and
+ * node2 and set NDN face to DOWN state
+ *
+ * Note that only PointToPointChannels are supported by this helper method
+ *
+ * @param node1 one node
+ * @param node2 another node
+ */
+ static void
+ FailLink (Ptr<Node> node1, Ptr<Node> node2);
+
+ /**
+ * @brief Fail NDN link between two nodes
+ *
+ * The helper will attempt to find NDN link between node1 and
+ * node2 and set NDN face to DOWN state
+ *
+ * Note that only PointToPointChannels are supported by this helper method
+ *
+ * This variant uses node names registered by Names class
+ *
+ * @param node1 one node's name
+ * @param node2 another node's name
+ */
+ static void
+ FailLinkByName (const std::string &node1, const std::string &node2);
+
+ /**
+ * @brief Re-enable NDN link between two nodes
+ *
+ * The helper will attempt to find NDN link between node1 and
+ * node2 and set NDN face to UP state
+ *
+ * Note that only PointToPointChannels are supported by this helper method
+ *
+ * @param node1 one node
+ * @param node2 another node
+ */
+ static void
+ UpLink (Ptr<Node> node1, Ptr<Node> node2);
+
+ /**
+ * @brief Re-enable NDN link between two nodes
+ *
+ * The helper will attempt to find NDN link between node1 and
+ * node2 and set NDN face to UP state
+ *
+ * Note that only PointToPointChannels are supported by this helper method
+ *
+ * This variant uses node names registered by Names class
+ *
+ * @param node1 one node's name
+ * @param node2 another node's name
+ */
+ static void
+ UpLinkByName (const std::string &node1, const std::string &node2);
+}; // end: LinkControlHelper
+
+
+} // ndn
+} // ns3
+
+#endif // NDN_LINK_CONTROL_HELPER_H