/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
* Copyright (c) 2010 Hemanth Narra, Yufei Cheng
*
* 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: Hemanth Narra <hemanth@ittc.ku.com>
* Author: Yufei Cheng <yfcheng@ittc.ku.edu>
*
* James P.G. Sterbenz <jpgs@ittc.ku.edu>, director
* ResiliNets Research Group http://wiki.ittc.ku.edu/resilinets
* Information and Telecommunication Technology Center (ITTC)
* and Department of Electrical Engineering and Computer Science
* The University of Kansas Lawrence, KS USA.
*
* Work supported in part by NSF FIND (Future Internet Design) Program
* under grant CNS-0626918 (Postmodern Internet Architecture),
* NSF grant CNS-1050226 (Multilayer Network Resilience Analysis and Experimentation on GENI),
* US Department of Defense (DoD), and ITTC at The University of Kansas.
*/
#ifndef DSDV_H_
#define DSDV_H_
/**
* \ingroup routing
* \defgroup dsdv
*
* \brief Destination-Sequenced Distance Vector (DSDV) routing protocol is a pro-active, table-driven routing protocol
* for MANETs developed by Charles E. Perkins and Pravin Bhagwat in 1994. It uses the hop count as metric in route
* selection.
*
* DSDV Routing Table: Every node will maintain a table listing all the other nodes it has known either directly
* or through some neighbors. Every node has a single entry in the routing table. The entry will have information
* about the node's IP address, last known sequence number and the hop count to reach that node. Along with these
* details the table also keeps track of the nexthop neighbor to reach the destination node, the timestamp of the last
* update received for that node.
*
* The DSDV update message consists of three fields, Destination Address, Sequence Number and Hop Count.
*
* Each node uses 2 mechanisms to send out the DSDV updates. They are,
* 1. Periodic Updates
* Periodic updates are sent out after every m_periodicUpdateInterval(default:15s). In this update the node broadcasts
* out its entire routing table.
* 2. Trigger Updates
* Trigger Updates are small updates in-between the periodic updates. These updates are sent out whenever a node
* receives a DSDV packet that caused a change in its routing table. The original paper did not clearly mention
* when for what change in the table should a DSDV update be sent out. The current implemntation sends out an update
* irrespective of the change in the routing table.
*
* The updates are accepted based on the metric for a particular node. The first factor determinig the acceptance of
* an update is the sequence number. It has to accept the update if the sequence number of the update message is higher
* irrespective of the metric. If the update with same sequence number is received, then the update with least metric
* (hopCount) is given precedence.
*
* In highly mobile scenarios, there is a high chance of route fluctuations, thus we have the concept of weighted
* settling time where an update with change in metric will not be advertised to neighbors. The node waits for
* the settling time to make sure that it did not receive the update from its old neighbor before sending out
* that update.
*
* The current implementation covers all the above features of DSDV. The current implementation also has a request queue
* to buffer packets that have no routes to destination. The default is set to buffer up to 5 packets per destination.
*
* Link to the Paper: http://portal.acm.org/citation.cfm?doid=190314.190336
*
*/
#endif /* DSDV_H_ */