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Versions: 00 01 02 03 04 05                                             
Mobile Ad Hoc Networking Working Group                        Namhi Kang
INTERNET DRAFT                                        DASAN Networks Inc.
17 October 2005                                             Younghan Kim
                                           University of Soongsil, Korea

                    Quality of Service Extension to
                Dynamic MANET OnDemand Routing Protocol
                       draft-kang-dymoqos-00.txt


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Copyright Notice

   Copyright (C) The Internet Society (2005).


Abstract

   This document describes extensions to the Dynamic MANET On-demand
   (DYMO) routing protocol in order to enable mobile nodes to discover
   and maintain QoS routes.  DYMO is a reactive (on-demand) routing
   protocol designed for use by mobile nodes in multi-hop wireless ad
   hoc networks.  Extensions of this document include the necessary
   addition to the routing table and the DYMO message element.



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1. Introduction


   The DYMO routing protocol specifies a reactive means to discover a
   route to the destination for MANET nodes. A source node disseminates
   RREQ message toward the destination node to discover a route to the
   node.  Once the RREQ message arrives at the destination node, it
   responds RREP message back to the source node over the discovered
   path by unicasting.  During such a route discovery process,
   intermediate nodes (i.e. nodes that relay the RREQ and RREP message)
   update its routing table based on the routing information that is
   present in those two messages for each direction.  DYMO also offers
   adaptation to changing network topology, which can be occurred by the
   mobility of nodes as the main cause, by means of the route
   maintenance mechanisms [1].

   In order to provide MANET nodes with QoS routes, extensions to DYMO
   message elements are required.  These extensions specify the service
   requirements (say maximum tolerable delay, maximum tolerable jitter,
   and/or minimum bandwidth limitation) that must be guaranteed by nodes
   along a route from a source to the destination.

   This document presents which extensions are required for support QoS
   in routing, how service guarantees are achieved by using the defined
   extensions without high impacts on the existing DYMO operations and
   how QoS routes are discovered and maintained are also briefly
   described.

   The extensions of this document conform to the DYMO routing protocol
   (i.e. the the extentions to DYMO data structure specified in [1]).

   In this document, the extension to routing table is first described
   and then two message element extensions, QoS Route Element (QRE) and
   QoS Route Error (QRERR), are presented for supporting QoS routing.

   The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [2].







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2. Routing Table Entries for QoS Routing

   In QoS routing, routing table entries can be defined differently
   according to the type of QoS model; per-flow based model such as
   IntServ model [3] or per-class based model such as DiffServ model
   [4].

   In case of the per-flow based mechanism, the following entries may be
   added to the routing table of each DYMO router on the path.  A
   routing table entry is defined for a flow to specify QoS requirements
   requested by the source (requestor) of the particular flow, where a
   flow can be identified by the pair of IP address and port number.

      -  Maximum Tolerable Delay

      -  Maximum Tolerable Jitter

      -  Minimum Available Bandwidth

      -  List of Sources Identifier Requesting Delay Guarantees

      -  List of Sources Identifier Requesting Jitter Guarantees

      -  List of Sources Identifier Requesting Bandwidth Guarantees,

      where the Source Identifier consists of IPSourceAddress and Port
      number.

   In case of the class-based model , on the other hand, the following
   fields may be added to the routing table of a DYMO router. Each
   routing table entry is defined for each pre-specified class, where a
   packet belonging to each class can be distinguished by DSCP (DiffServ
   Code Point) as specified in [5].

      -  Maximum Tolerable Delay

      -  Maximum Tolerable Jitter

      -  Minimum Available Bandwidth

      -  List of Classes

      -  List of Sources Identifier Belonging to Each Class



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3. Extensions to DYMO Message Elements

   In this section, we present two extensions to DYMO message element
   for support QoS route.  The work especially considers the compact
   representation for use by mobile nodes in using of limited capacity,
   the future extensions for covering various QoS parameters and the
   support of the per-flow based mechanism and the per-class based
   mechanism as well.


3.1 QoS Routing Element (QRE)


   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |          Len          |    TTL    |I|A|  Res  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   :                   NotifyAddress (QoS Requestor)               :
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   :                         TargetAddress                         :
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         TargetSeqNum                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   :                                                               :
   :                   QoS Information Block (QIB)                 :
   :                                                               :
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   :                                                               :
   :                QoS State Information Block (QSIB)             :
   :                                                               :
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  THopCnt  |Res|                                               :
   +-+-+-+-+-+-+-+-+                                               :
   :                                                               :
   :                    Routing Blocks (RBlocks)                   :
   :                                                               :
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                  Figure 1. QoS Routing Element (QRE)

   QoS Routing Element (QRE) is an extension to the DYMO Routing Element



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   (RE) in order to enable a source to discover a path that is able to
   guarantee the QoS requirements.  The QoS requirements of the source
   are specified in the QIB (QoS Information Block) field.

   Element Type (Type)
         The Type field identifies that this element is QRE and the han-
         dling by nodes that do not implement or understand QoS exten-
         sions. The data structure of the Type is as follows.


              0                          0
              0 1 2 3 4 5 6 7 8          0 1 2 3 4 5 6 7 8
              +-+-+-+-+-+-+-+-+          +-+-+-+-+-+-+-+-+
              |     Type      |     =    |M| H |         |
              +-+-+-+-+-+-+-+-+          +-+-+-+-+-+-+-+-+

                             Figure 2. Type

         In QRE, M bit MUST be set to one (1) in order to indicate that
         QRE requires notification via an UERR when QRE is not under-
         stood or handled by a node on the path.  Therefore QRE MUST
         convey NotifyAddress field to which UERR is sent.  As well as
         the H bits in the Type field MUST set to (11) in order to force
         a node which does not support QRE to drop the QRE packet with-
         out processing any other QoS DYMO elements.

   NotifyAddress (QoS Requestor)
         IP address of the source that have originally generated this
         QRE to request a particular service.

   Most of fields conform to the DYMO message element specified in [2]
   except the newly defined two information block fields (i.e. QoS
   Information Block (QIB) and QoS State Information Block (QSIB)).
   Those two blocks are defined as follows.

   QoS Information Block (QIB)
         This field can be used differently according to the type of
         element message (i.e. in a route request and a route reply ele-
         ment with QoS extensions).  In QRREQ message, on one hand, the
         QIB field indicates the service requirements that must be met
         at nodes along a route to the destination.  On the other hand,
         in QRREP message, the destination uses this field to inform the



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         route's resources available for the QoS requestor.  The route's
         resources are gathered or updated by intermediate nodes and
         contained within the QSIB field during the route discovery
         process.  The data structure of QIB field is described in Fig-
         ure 3.


   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |QPCnt| QoS PM  |Res|Traffic Cls|      QoS Param Value 1        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |QoS Param Value N(if presented)|   Padding Bits (if needed)    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                 Figure 3. QoS Information Block (QIB)

   QoS Parameter Count (QPCnt)
         The most significant 3 bits, QPCnt bits, indicate the number of
         QoS parameters being presented within the QIB field.

   QoS Parameter Mark (QoS PM)
         The 5 bits marker of QoS PM field specifies which parameter is
         present in QIB to specify the service requirements. This field
         consists of the following bit marker.


              0                          0
              0 1 2 3 4 5 6 7 8          0 1 2 3 4 5 6 7 8
              +-+-+-+-+-+-+-+-+          +-+-+-+-+-+-+-+-+
              |    QoS PM     |     =    |B|D|J|   Res   |
              +-+-+-+-+-+-+-+-+          +-+-+-+-+-+-+-+-+

                Figure 4. QoS Parameter Marker (QoS PM)

      B-bit (B)
         1-bit marker to indicate whether the minimum bandwidth is spec-
         ified as one of the service requirements within QIB.

      D-bit (D)
         1-bit marker to indicate whether the maximum delay (end to end
         delay) is specified as one of the service requirements within



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         QIB.

      J-bit (J)
         1-bit marker to indicate whether the maximum jitter (end to end
         jitter) is specified as one of the service requirements within
         QIB.

      Reserved (Res)
         Reserved 2 bits for the future extensions (i.e. for other QoS
         parameters such as power of a node).  Typically, these bits are
         set to zero (0) and ignored in any processing.  In addition to
         these 2 bits, there exist two more bits at the next field
         (between QoS PM and Traffic Class fields).  These Res bits also
         can be used for the future extensions.  (At the time of writing
         this document, these two Res fields are conceptually distin-
         guished in order to support easy to implement, i.e. byte based
         variable allocation in conventional programming language such
         as C.)

   Traffic Class (Traffic Cls)
         The Traffic Cls field allows mobile nodes to employ the per-
         class based mechanism (say DiffServ). This field is specified
         by using 6-bits code, called DSCP (Differentiated Services Code
         Points) that indicate a particular class.

   QoS parameter value (QoS Param Value)
         The number and the type of QoS parameters depend on the first
         16 bytes of QIB as above addressed. If B and D bit are set to
         one (1), for example, there MUST exist two parameter value
         fields so that the padding field does not needed.  QoS Param
         Value fields are defined as follows.

         - Minimum Bandwidth Requirement
         16-bit number, measured in kbits/second (kbps). The maximum
         value is about 131 Mbps (2^17 - 1 kbps). If the required band-
         width is less than 1kbps, the value is set to one (1) That is,
         the least bandwidth requirement the source requires is 1 Kbps.

         - Maximum End to End Delay Requirement
         16-bit number, measured in milliseconds (ms)

         - Maximum End to End Jitter Requirement



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         16-bit number, measured in milliseconds (ms)

   Padding Bits
         The Padding field of QIB is used to confirm to DYMO message
         element.  If QoS PCnt is even number then these bits are set to
         zero (0).


   QoS State Information Block (QSIB)
         In QoS routing, intermediate nodes along a path to the destina-
         tion should inform the destination about its current state of
         resources in order that the destination is able to decide the
         optimal route among route candidates.  The number and the kinds
         of QoS State Value depend on the QIB field.  As an example, if
         a source specifies a delay parameter as a QoS requirement (i.e.
         D bit in QoS PM field is set), there MUST exist a QoS state
         value in SIB for presenting a delay value on candidate paths.
         In this case, all intermediate nodes MUST accumulate its mea-
         sured delay. The data structure of the QSIB is illustrated in
         figure 5.


   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       QoS State Value 1       |QoS State Value N(if presented)|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |QoS State Value N(if presented)|   Padding Bits (if needed)    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

            Figure 5. QoS State Information Block (QoS SIB)



3.2 QoS Route Error (QRERR)

   QoS Route Error (QRERR) is an extension to the DYMO RERR message ele-
   ment.  QRERR message element is generated when an intermediate node
   realizes a lack of ability to maintain the QoS guarantees for a spe-
   cific route.  The data structure of this element is as follows.





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   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |          Len          |    TTL    |I|Reserved |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   :                         QUNodeAddress1                        :
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         QUNodeSeqNum1                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           UQParam1                            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   :               Additional QUNodeAddressN (if needed)           :
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |               Additional QUNodeSeqNumN (if needed)            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                   Figure 6. QoS Route Error (QRERR)

   QoS Unsupported Node Address (QUNodeAddress)
         The IP address of the node that cannot guarantee QoS any more.

   QoS Unsupported Node Sequence Number (QUNodeSeqNum)
         The sequence number of the node that cannot guarantee QoS, if
         known; otherwise this field set to zero (0).

   Unsupported QoS Parameter (UQParam)
         The main difference between RERR and QRERR is the UQParam
         (Unsupported QoS Parameter) field which is used to inform the
         QoS requestor about which QoS parameter is no longer available
         for the originally specified QoS requirements. Once the QoS
         requestor receives the QRERR, it re-builds a QoS route process
         based on the unavailable QoS parameters if it still has packets
         to deliver. This field is illustrated in figure 7.


   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |QPCnt| QoS PM  |Res|Traffic Cls|      QoS Param Value 1        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |QoS Param Value N(if presented)|   Padding Bits (if needed)    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                            Figure 7. UQParam field



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   All fields are equivalent to the fields of QIB in the QRE message
   element but differently used. QoS PCnt indicates the number of scarce
   resource and each of their kinds are marked in QoS PM filed to iden-
   tify the next fields (i.e. which parameter(s) is (are) present in
   UQParam field).

   QoS Parameter Value
         The QoS Parameter Value field reports the measured QoS parame-
         ter(s) that fails to meet the originally requested QoS. If a
         particular node is aware of higher delay than the maximum per-
         missible delay, the measured delay is reported to the QoS
         requestor.

   The QRERR message MUST be delivered to all QoS requestor potentially
   affected by the change in the QoS parameter.


4. QoS DYMO Operations


4.1 QoS Route Discovery

   Like DYMO routing procedures, a QoS route is also discovered by means
   of two way handshaking consisting of a route request and route reply
   cycle.  Instead of DYMO RREQ, the source (QoS requestor) disseminates
   QRREQ (RREQ with a QoS extension) to the destination.  QRREQ message
   elements therefore should contain required QoS parameters as well as
   the QoS reporting information on the path that the message has been
   experienced.  Thereafter, the destination node decides a correct
   route that can meet the QoS requirements and then sends QRREP (RREP
   with a QoS extension) to the source.

   Ahead of re-broadcasting a QRREQ message by an intermediate node, the
   node must check its resources whether it is available for the QoS
   requirements contained within the QRREQ message during the route dis-
   covery process.  Thereafter, if resources are enough to meet service
   requirements, the intermediate node updates QoS information that is
   present in the QRREQ message to inform the destination about the cur-
   rent QoS states related to the path.




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   That is, QRREQ should contain two different fields.  One is used to
   specify the QoS requirements of the source (i.e. QoS requestor) that
   must be met at nodes through the path.  The other field is used to
   inform both the QoS requestor and the destination that selects a
   proper QoS route the current network conditions such as delay, jit-
   ter, and/or bandwidth.

   In case of delay and jitter, intermediate nodes accumulate each of
   their measured delay and jitter value to the corresponding value of
   the received QRREQ message.  For this reason, the destination can be
   aware of the end to end delay and jitter along the path.


   In case of bandwidth (i.e. capacity to transmit), the node compares
   its measured value with the value of QSIB field in the received QRREQ
   message. If the measured value is smaller than the value of the mes-
   sage, the field is updated to the measured one.  This field allows
   the destination to be aware of the actual minimum bandwidth over a
   route from the source to the destination since the value of QSIB is
   always bigger than the minimum value that the QoS requestor requires.
   If it is not the case, a node MUST drop the QRREQ message since there
   is not enough bandwidth to guarantee the required one. Such a way
   allows the QoS requestor to be able to increase the minimum bandwidth
   requirement according to the network condition dynamically.


   In QoS enabled DYMO, M-bit MUST be set to one (1) and H-bits MUST be
   set to (11).  Therefore, if the QoS extended element is not supported
   or handled by the processing node, the node MUST send a UERR to the
   NotifyAddress (QoS requestor) and drop the message to prevent that
   unsupported message is not propagated further.

   In DYMO, I bit of RE message indicates whether the element has been
   ignored by some intermediate nodes. Therefore, in QoS DYMO, if the I
   bit is (1), the QRE message MUST be dropped.


4.2 QoS Route Maintenance

   In order to react to changes in the network resources, nodes monitor
   their links under the aspect of QoS.  When a node is aware of the
   fact that resources of its link is no longer available for the QoS



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   requestor, a QoS-Route Error (QRERR) is sent to the QoS requestor to
   inform the current unavailable QoS parameters of the route. Once the
   requestor receives the QRERR, it re-builds a QoS route process based
   on the unavailable QoS parameters if it still has packets to deliver.


5. Security Considerations

   This document does not discuss any special security concerns in
   detail.  The protocol of this document is built on the assumption
   that all participating nodes are trusted each other as well as there
   is no adversary who modifies/injects false route elements to corrupt
   the QoS routes.

   However, support of secure routing protocol is prerequisite for
   launching a secure communication in the presence of adversaries.  In
   such an environment, most of all MANET routing protocols including
   DYMO are vulnerable to many kinds of attacks.  It is fairly easy to
   inject fake routing messages or modify legitimate ones so that net-
   work operation would be heavily disturbed (e.g., by creating loops or
   disconnecting the network).  Therefore, it is necessary to find a
   means to authenticate/verify control messages to discover and main-
   tain a proper route.  Especially, QRE message MUST be authenticated
   to enable nodes participating in QoS DYMO routing protocol to assure
   the origin of the QRE message.


References

   [1] I. Chakeres, E. M. Belding-Royer and C. E. Perkins. Dynamic MANET
   On-demand (DYMO) Routing. IETF Internet Draft draft-ietf-manet-
   dymo-02 June 2005. Work in Progress.

   [2] S. Bradner. Key words for use in RFCs to Indicate Requirement
   Levels.  Internet RFC 2119, March 1997.

   [3] R. Braden, D. Clark, and S. Shenker, Integrated Services in the
   Internet Architecture: an Overview, Internet RFC 1633, June 1994.

   [4] S. Blake, D. Black, M. Carlson, E. Davies, Z. Wang, and W. Weiss,
   An Architecture for Differentiated Services Internet RFC 2475, Decem-
   ber 1998.



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   [5] Nichols, K., Blake, S., Baker, F. and D. Black. Definition of the
   Differentiated Services Field (DS Field) in the IPv4 and IPv6 Head-
   ers, Internet RFC 2474, December 1998.



   Author's Addresses

      Questions about this memo can be directed to:

         Namhi Kang
         Ubiquitous Network Research Center
         DASAN Networks Inc.
         3F FineVenture Bldg. 345-1, YaTap-Dong,
         BunDang-Gu, SeongNam-Si, KyongGi-Do, 463-070
         Korea
         +82 2 814 0151
         nalnal@dcn.ssu.ac.kr

         Younghan Kim
         University of Soongsil in Seoul
         11F Hyungnam Engineering Bldg. 317, Sangdo-Dong,
         Dongjak-Gu, Seoul 156-743
         Korea
         +82 2 820 0904
         yhkim@dcn.ssu.ac.kr



















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