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diff --git a/src/lib/dhcp/packet_queue.h b/src/lib/dhcp/packet_queue.h
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+++ b/src/lib/dhcp/packet_queue.h
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+// Copyright (C) 2018-2022 Internet Systems Consortium, Inc. ("ISC")
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#ifndef PACKET_QUEUE_H
+#define PACKET_QUEUE_H
+
+#include <cc/data.h>
+#include <dhcp/socket_info.h>
+#include <dhcp/pkt4.h>
+#include <dhcp/pkt6.h>
+
+#include <sstream>
+
+namespace isc {
+
+namespace dhcp {
+
+/// @brief Invalid queue parameter exception
+///
+/// Thrown when packet queue is supplied an invalid/missing parameter
+class InvalidQueueParameter : public Exception {
+public:
+    InvalidQueueParameter(const char* file, size_t line, const char* what) :
+        isc::Exception(file, line, what) {}
+};
+
+/// @brief Enumerates choices between the two ends of the queue.
+enum class QueueEnd {
+    FRONT,  // Typically the end packets are read from
+    BACK    // Typically the end packets are written to
+};
+
+/// @brief Interface for managing a queue of inbound DHCP packets
+///
+/// This class serves as the abstract interface for packet queue
+/// implementations which may be used by @c IfaceMgr to store
+/// inbound packets until they are a dequeued for processing.
+///
+/// @tparam PacketTypePtr Type of packet the queue contains.
+/// This expected to be either isc::dhcp::Pkt4Ptr or isc::dhcp::Pkt6Ptr
+///
+/// @note Derivations of this class MUST BE thread-safe.
+template<typename PacketTypePtr>
+class PacketQueue {
+public:
+
+    /// @brief Constructor
+    ///
+    /// @param queue_type logical name of the queue implementation
+    /// Typically this is assigned by the factory that creates the
+    /// queue.  It is the logical name used to register queue
+    /// implementations.
+    explicit PacketQueue(const std::string& queue_type)
+        :  queue_type_(queue_type) {}
+
+    /// Virtual destructor
+    virtual ~PacketQueue(){};
+
+    /// @brief Adds a packet to the queue
+    ///
+    /// Adds the packet to the queue.  Derivations determine
+    /// which packets to queue and how to queue them.
+    ///
+    /// @param packet packet to enqueue
+    /// @param source socket the packet came from
+    virtual void enqueuePacket(PacketTypePtr packet, const SocketInfo& source) = 0;
+
+    /// @brief Dequeues the next packet from the queue
+    ///
+    /// Dequeues the next packet (if any) and returns it. Derivations determine
+    /// how packets are dequeued.
+    ///
+    /// @return A pointer to dequeued packet, or an empty pointer
+    /// if the queue is empty.
+    virtual PacketTypePtr dequeuePacket() = 0;
+
+    /// @brief return True if the queue is empty.
+    virtual bool empty() const = 0;
+
+    /// @brief Returns the current number of packets in the buffer.
+    virtual size_t getSize() const = 0;
+
+    /// @brief Discards all packets currently in the buffer.
+    virtual void clear() = 0;
+
+    /// @brief Fetches operational information about the current state of
+    /// the queue
+    ///
+    /// Creates and returns an ElementPtr containing a single entry,
+    /// "queue-type".  Derivations are expected to call this method first
+    /// and then add their own values.  Since implementations may vary
+    /// widely on data of interest, this is structured as an ElementPtr
+    /// for broad latitude.
+    ///
+    /// @return an ElementPtr containing elements for values of interest
+    virtual data::ElementPtr getInfo() const {
+       data::ElementPtr info = data::Element::createMap();
+       info->set("queue-type", data::Element::create(queue_type_));
+       return(info);
+    }
+
+    /// @brief Fetches a JSON string representation of queue operational info
+    ///
+    /// This method calls @c getInfo() and then converts that into JSON text.
+    ///
+    /// @return string of JSON text
+    std::string getInfoStr() const {
+       data::ElementPtr info = getInfo();
+       std::ostringstream os;
+       info->toJSON(os);
+       return (os.str());
+    }
+
+    /// @return Fetches the logical name of the type of this queue.
+    std::string getQueueType() {
+        return (queue_type_);
+    };
+
+private:
+    /// @brief Logical name of the this queue's implementation type.
+    std::string queue_type_;
+
+};
+
+/// @brief Defines pointer to the DHCPv4 queue interface used at the application level.
+/// This is the type understood by IfaceMgr and the type that should be returned by
+/// DHCPv4 packet queue factories.
+typedef boost::shared_ptr<PacketQueue<Pkt4Ptr>> PacketQueue4Ptr;
+
+/// @brief Defines pointer to the DHCPv6 queue interface used at the application level.
+/// This is the type understood by IfaceMgr and the type that should be returned by
+/// DHCPv6 packet queue factories.
+typedef boost::shared_ptr<PacketQueue<Pkt6Ptr>> PacketQueue6Ptr;
+
+}; // namespace isc::dhcp
+}; // namespace isc
+
+#endif // PACKET_QUEUE_H