One document matched: draft-irtf-dtnrg-ipnd-01.txt

Differences from draft-irtf-dtnrg-ipnd-00.txt




Network Working Group                                          D. Ellard
Internet-Draft                                                  D. Brown
Intended status: Experimental                  Raytheon BBN Technologies
Expires: September 9, 2010                                 March 8, 2010


                    DTN IP Neighbor Discovery (IPND)
                        draft-irtf-dtnrg-ipnd-01

Abstract

   Disruption Tolerant Networking (DTN) IP Neighbor Discovery (IPND), is
   a method for otherwise oblivious nodes to learn of the existence,
   availability, and addresses of other DTN participants.  IPND both
   sends and listens for small IP UDP announcement "beacons."  Beacon
   messages are addressed to an IP unicast, multicast, or broadcast
   destination to discover specified remote neighbors, or unspecified
   local neighbors in the topology, e.g. within wireless range.  IPND
   beacons advertise neighbor availability by including the DTN node's
   canonical endpoint identifier.  IPND beacons optionally include
   service availability and parameters.  In this way, neighbor discovery
   and service discovery may be coupled or decoupled as required.  Once
   discovered, new neighbor pairs use advertised availabilities to
   connect, exchange routing information, etc.  This document describes
   DTN IPND.

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on September 9, 2010.



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Copyright Notice

   Copyright (c) 2010 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
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   the Trust Legal Provisions and are provided without warranty as
   described in the BSD License.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Protocol Description . . . . . . . . . . . . . . . . . . . . .  5
     2.1.  Beacon Period  . . . . . . . . . . . . . . . . . . . . . .  5
     2.2.  Unknown Neighbors  . . . . . . . . . . . . . . . . . . . .  5
     2.3.  Enumerated Neighbors . . . . . . . . . . . . . . . . . . .  6
     2.4.  Allowing Data to Substitute for Beacons  . . . . . . . . .  6
     2.5.  Discovering Bidirectional Links  . . . . . . . . . . . . .  7
     2.6.  Beacon Message Format  . . . . . . . . . . . . . . . . . .  7
       2.6.1.  Services . . . . . . . . . . . . . . . . . . . . . . .  9
       2.6.2.  Neighborhood Bloom Filter  . . . . . . . . . . . . . . 10
     2.7.  IPND and CLAs  . . . . . . . . . . . . . . . . . . . . . . 10
     2.8.  Disconnection  . . . . . . . . . . . . . . . . . . . . . . 11
   3.  Relation to Other Discovery Protocols  . . . . . . . . . . . . 12
   4.  Implementation Experience  . . . . . . . . . . . . . . . . . . 13
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . . 14
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 15
   7.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
     7.1.  Normative References . . . . . . . . . . . . . . . . . . . 16
     7.2.  Informative References . . . . . . . . . . . . . . . . . . 16
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18












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1.  Introduction

   Delay and Disruption Tolerant Networks (DTNs) [RFC4838] make no
   presumptions about network topology, routing, or availability.  DTNs
   therefore attempt to provide communication in challenged environments
   where, for instance, contemporaneous end-to-end paths do not exist.
   Examples of such DTNs arise in a variety of contexts including mobile
   social networks, space communications, rural message delivery,
   military networks, etc.

   In many DTN scenarios, the identity and meeting schedule of
   participating nodes is not known in advance.  Therefore, an important
   primitive is Neighbor Discovery (ND), or the ability to dynamically
   discover other DTN nodes.  This document specifies Internet Protocol
   Neighbor Discovery (IPND).  In contrast to link or physical layer
   discovery, IPND enables a general form of neighbor discovery across a
   heterogeneous range of links, as are often found in DTN networks.
   IPND is particularly useful in mobile, ad-hoc DTN environments where
   meeting opportunities are not known a priori and connections may
   appear or disappear without warning.  For example, two mobile nodes
   might come into radio distance of each other, discover the new
   connection, and move data along that connection before physically
   disconnecting.

   In addition to discovering neighbors, it is often valuable to
   simultaneously discover services available from that neighbor.
   Examples of DTN services include a neighbor's available Convergence
   Layer Adapters (CLAs) and their parameters (e.g.  [TCPCLA]),
   available routers (e.g.  [PROPHET]), tunnels, etc.  Newly discovered
   nodes will then typically participate in bundle [RFC5050] routing and
   delivery.

   In other situations it is useful to decouple service discovery from
   neighbor discovery for efficiency and generality.  For example, upon
   discovering a neighbor, a DTN node might initiate a separate
   negotiation process to establish 1-hop connectivity via a particular
   convergence layer, perform routing setup, exchange availability
   information, etc.

   IPND beacons thus optionally advertise a node's available services
   while maintaining the ability to decouple node and service discovery
   as necessary.  This flexibility is important to various DTN use
   scenarios where connection opportunities may be limited (thus
   necessitating an atomic message for all availability information),
   bandwidth might be scarce (thus implying that service discovery
   should be an independent negotiation to lower beacon overhead), or
   connections have very large round-trip-times (service negotiation is
   therefore too costly with respect to time).



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   DTN IPND is designed to be simple, efficient, and general.

   Although this document describes a neighbor discovery protocol in
   terms of IP, the principles and basic mechanisms used in this
   protocol may also be expressed in terms of other datagram protocols.

   The remainder of this document describes DTN IPND.

1.1.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

   The following terminology is used for describing DTN IPND.

   Bundle  A PDU as defined in [RFC5050].

   Node  A DTN entity in the network that receives and processes
      bundles.

   Beacon message  An IPND-specific message, defined in this document,
      used to announce the presence of a DTN node and parameters with
      which to connect to that node.

   Convergence layer adapter  A convergence layer adapter (CLA) sends
      and receives bundles on behalf of a node by providing the
      conversion between bundles and a transport protocol such as TCP or
      UDP.






















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2.  Protocol Description

   Nodes use DTN IPND beacons, small UDP messages in the IP underlay, to
   advertise presence.  Similarly, IPND beacons received from other
   nodes serve to detect the availability of DTN neighbors.  Nodes
   SHOULD both send and receive beacons.  These beacon messages,
   detailed in Section 2.6, may be sent either as IP unicast, multicast,
   or broadcast UDP packets.  The beacon message content is agnostic to
   the underlying transport mode.

   Broadcast beacons are designed to reach unknown neighbors in
   neighborhoods within the local network broadcast domain.  Multicast
   [RFC1112] beacons extend the scope of beacon dissemination to
   potentially include multiple networks across routed boundaries.  On
   broadcast media such as Ethernet or wireless, multicast and broadcast
   beacons are sent as link-layer broadcast messages.

   Broadcast and multicast discovery are described in Section 2.2.  In
   contrast, unicast beacons are sent only to explicitly known and
   enumerated neighbors as described in Section 2.3.

   Upon discovering a neighbor, IPND can establish a connection to the
   new neighbor via an IP-based Convergence Layer Adapter (CLA), for
   example the TCP [TCPCLA] or UDP [UDPCLA] CLA.  The CLA then
   negotiates the connection per its individual specification and
   installs the appropriate next-hop routing information in the local
   node.

2.1.  Beacon Period

   An IPND implementation SHOULD send beacons periodically.  The time
   interval between beacons SHOULD be appropriate for the conditions of
   the network and MAY be configurable.

   A receiving node SHOULD know the expected beacon interval and use
   this parameter, along with the existence and time of received beacons
   to determine whether state of the sender's ability to transmit to the
   receiver, i.e., the up or down state of the sender to receiver link.
   The exact algorithm for determining the link status based on received
   beacons is implementation-defined.

2.2.  Unknown Neighbors

   In the general case, the IP addresses of potential neighbors are not
   known in advance.  To discover unknown neighbors, IPND beacon
   messages are sent as IP packets with either multicast or broadcast
   destination addresses.  IPND MUST support multicast IP destination
   addresses [RFC1112] and multicast IGMP group membership [RFC3376].



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   IPND MAY support IP broadcast destinations.  IPND multicast addresses
   SHOULD be from the IANA assigned local network control block
   224.0.0/24 [RFC3171].  This block of multicast addresses is
   intentionally scoped to the local network to prevent dissemination to
   the wider Internet.

   IPND MAY also use other multicast addresses as required, such as
   multicast addresses from the IANA assigned Internetwork Control Block
   [RFC3171].

   In all cases, IPND MUST support a configurable IP time-to-live value
   for all beacon messages.

2.3.  Enumerated Neighbors

   IPND MUST support multicast or broadcast beacons and SHOULD support
   both.  IPND SHOULD support unicast beacons.  Since multicast or
   broadcast discovery is not feasible over internetworks, the IP
   addresses of potential neighbors reachable only across multiple
   underlay hops must be explicitly enumerated for discovery.  While the
   neighbor's address is therefore known, the availability of that
   neighbor is not known.  IPND thus permits DTN nodes to discover
   available remote neighbors across multiple IP underlay hops when
   provided with the addresses of those neighbors.  In this way, IPND
   can be used to bridge IP-based DTNs while detecting disconnections
   among and between the DTNs.

2.4.  Allowing Data to Substitute for Beacons

   Sending data to an IP address matching a configured beacon
   destination SHOULD suppress the generation of beacon messages to that
   destination for a period of time up to but no longer than the beacon
   sending interval.  This suppression SHOULD NOT occur if the
   parameters of a new beacon message would differ from the preceding
   beacon including the advertised services (Section 2.6.1) or
   Neighborhood Bloom Filter (NBF) (Section 2.6.2).

   Upon receiving a data packet from a neighbor where the packets do not
   represent a beacon, a node SHOULD behave as if a beacon had been
   received from that neighbor, as follows.  If the data packet is
   addressed to this node via a unicast address, then the behavior
   SHOULD be as if the implied received beacon contains a Neighborhood
   Bloom Filter which indicates the membership of the receiving node in
   the sender's 1-hop neighborhood.  Otherwise, if the destination
   address is multicast or broadcast, then the receiving node should
   presume that the link is bidirectional if and only if its state was
   bidirectional prior to receiving the data packet.  See Section 2.5.
   The sender's advertised services are presumed to be unchanged since



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   the sender's last received beacon.  If no beacons have previously
   been received from such a neighbor, then it is presumed that there
   are no services associated with the sender.

2.5.  Discovering Bidirectional Links

   Many routing protocols work correctly only when links are
   bidirectional.  In wired IP networks, link bidirectionality can often
   be presumed.  For other types of networks, such as Mobile Ad-Hoc
   Networks (MANETs) this assumption often does not hold.  If a link to
   a neighbor is said to be "up" only because one or more beacon
   messages have been received from that neighbor over a wireless
   medium, it is not generally safe to assume that the link is
   bidirectional.  In practice, MANET networks often have links that are
   only unidirectional due to differences in antennae, transmit power,
   hardware variability, multi-path effects, etc.

   To discover the bidirectionality of links, an IPND Neighborhood Bloom
   Filter (NBF) (Section 2.6.2) facility MAY be employed in which each
   node advertises a Bloom filter representation of the set of neighbors
   from whom it has received enough recent beacons to be considered
   "up".  Upon receiving a beacon from an "up" neighbor that advertises
   an NBF which represents a set containing the receiving node's ID,
   then the link SHOULD be considered bidirectional.

2.6.  Beacon Message Format

   Figure 1 depicts the format of beacon messages.  Note that IPND
   follows the DTN convention of using Self-Delimiting Numeric Values
   (SDNVs) [SDNV] to represent variable length integers (denoted by *).
   IPND MUST use UDP checksums to ensure correctness.

   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Version    |     Flags     |     Beacon Sequence Number    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          EID Len  (*)         |   Canonical EID (variable)    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   /                    Service Block (optional)                   /
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  NBF Length (*) (optional)    |    NBF Bloom Filter Bits      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                      Figure 1: Beacon Message Format




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   The beacon message is comprised of the following fields:

   o  Version: An 8-bit field indicating the version of IPND that
      constructed this beacon.  The present document describes version
      0x02 of IPND.  This version field is incremented for IPND if
      either the IPND protocol is modified or the Bundle Protocol
      version is incremented.  In this way the field can also be used to
      determine the BP version supported by a potential DTN neighbor.

   o  Flags: An 8-bit field indicating IPND processing flags.  Two flags
      are currently defined. 0x00 indicates that no special processing
      should be performed on the beacon.  Semantics of bits are
      described here from least significant (LSb) to most significant
      (MSb).

      Bit 0  Source EID present: iff set, indicates that the source
         node's EID is present in the beacon.  If the EID is present, it
         is preceded by an SDNV indicating its length.

      Bit 1  Service Block present: iff set, indicates that a service
         block is present.

      Bit 2  Neighborhood Bloom Filter present: iff set, indicates that
         a Neighbor Bloom Filter is present.

   o  Beacon sequence number: A two-octet unsigned integer value
      incremented once for each beacon transmitted to a particular IP
      address.

   o  EID Length: The byte length of the canonical EID contained in the
      beacon.  The EID length field is an SDNV and is therefore variable
      length.  A two-octet length is shown for convenience of
      representation.

   o  Canonical EID: The canonical end node identifier of the neighbor
      advertised by the beacon message.  The canonical EID is variable
      length and represented as a Uniform Resource Identifier [RFC3986].

   o  Service Blocks: (Section 2.6.1) Optional announced services in the
      beacon.

   o  Neighborhood Bloom Filter: (Section 2.6.2) Optional length-
      prefixed bitfield representing the source node's 1-hop
      neighborhood.







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2.6.1.  Services

   As described previously, beacon messages may optionally include
   service availability information.  The services are intended to
   represent available CLAs, routers, etc., but are sufficiently general
   to accommodate unanticipated services provided by the advertising
   node.

   For example, the source IP address of a received beacon suffices to
   identify the remote node at the IP level.  However, the IP address
   alone does not inform other processes via which transport mechanism
   (e.g.  TCP or UDP) or via which transport port the remote node is
   offering a connection.  Similarly, nodes do not know which routers
   (e.g.  [PROPHET]) are running on a remote node in order to inform
   bundle exchange.  Therefore, beacons may contain service blocks.

   The format of a service block is given in Figure 2.

   +-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Number of services (*) |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Service Name Len (*)  | Service Name (variable)       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Service 1
   |   Service Param Len (*) | Service Parameters (variable) |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Service Name Len (*)  | Service Name (variable)       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Service 2
   |   Service Param Len (*) | Service Parameters (variable) |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+    ...


                      Figure 2: Service Block Format

   A service block is comprised of the following fields:

   o  Number of services: The number of services described in the block.

   o  Service Name Length: The length of the advertised service name or
      description.  The service name length is an SDNV and is therefore
      variable length.  The service name MUST have non-zero length.

   o  Service Name: An identifying name for the service, e.g.  "UDPCLA."

   o  Service Parameters Length: The length of service-specific
      parameters that accompany this announcement.  The service
      parameters length is an SDNV and is therefore variable length.





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   o  Service Parameters: Service-specific parameters required to use
      the service, e.g. "port=4453."

2.6.2.  Neighborhood Bloom Filter

   In order to efficiently determine link bidirectionality, a node
   represents the set of its 1-hop neighbors using a Bloom filter
   referred to as the Neighborhood Bloom Filter (NBF).  Upon receiving a
   beacon from a neighbor that contains an NBF, a node can quickly
   determine whether it is in the neighbor's NBF set, and thereby
   determine whether the link is bidirectional.

   Every node that might operate in an environment where discovered
   links may not be bidirectional SHOULD include a Bloom filter in some
   of its beacons which describes the membership of its 1-hop neighbor
   set.  The bits to set in the Bloom filter MUST be computed by
   computing hash(es) on the canonical EID of each 1-hop neighbor
   considered to be "up".

   Different networks naturally have distinct requirements, tolerance
   for overhead, and node computing resources, so the parameters of the
   Bloom filter such as length, number and types of hash algorithms,
   etc., are not mandated by IPND.  However, all nodes participating in
   such a DTN MUST use the same Bloom filter representation and
   parameters if they send Bloom filters.

   Bloom filter data, if present, MAY be ignored by a node if its
   implementation does not provide for it, or if the parameters of the
   Bloom filter cannot be determined with certainty.

   Nodes in DTNs with a likelihood of unidirectional links SHOULD
   provide Bloom filter data in some broadcast or multicast beacons if
   the routing protocol in use presumes that links are bidirectional.

   A neighborhood Bloom filter need not be included on every beacon, but
   one SHOULD be present on at least one broadcast or multicast beacon
   following a change in the 1-hop neighborhood of the node.  A
   neighborhood Bloom filter MAY be present on every broadcast or
   multicast beacon beacon.

   A Bloom filter, if included in a beacon message, MUST be represented
   by an SDNV, and MUST follow Service Blocks field, if present, or the
   Canonical EID field if the Service Blocks field is not present.

2.7.  IPND and CLAs

   IP-based CLAs are generally expected to depend on an IPND
   implementation module for their discovery service.  A CLA MAY opt not



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   to use IPND, either because that CLA does not require discovery or
   provides its own.

   Once IPND discovers a new neighbor it MUST inform all CLAs which
   depend on IPND of the neighbor's existence and the discovered
   parameters.  The exact means by which IPND communicates with the CLAs
   is implementation dependent.

   Similarly, once IPND determines that a link has gone down, it MUST
   inform all dependent CLAs of the link down event.

2.8.  Disconnection

   Note that IPND SHOULD maintain state over all existing neighbors in
   order to prevent CLAs from needlessly attempting to establish
   connections between nodes that are already connected.  To maintain
   the current neighbor set, IPND removes stale neighbors after the
   defined neighbor receive timeout period elapses without receiving any
   beacon messages from a particular neighbor.

   Upon detecting a neighbor that is no longer available, IPND MAY
   provide hints to the CLA that the neighbor is gone.  Note that some
   CLAs themselves provide keepalive-type functionality and therefore
   IPND is not necessarily required to detect down neighbors.  However,
   placing both discovery and availability information in IPND provides
   a single, coherent point in the system design to maintain neighbor
   information.
























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3.  Relation to Other Discovery Protocols

   A variety of discovery protocols exist in other contexts and domains.
   These discovery protocols include the ability to discover available
   neighbors and services.  For example, the IETF zero configuration
   working group [RFC3927], the bonjour protocol [BONJOUR], and the OLSR
   discovery protocol [NHDP] all provide similar functionality.

   Other rendezvous mechanisms are possible that allow a node to find a
   neighbor of a particular type or with particular properties.  For
   example, the Domain Name System (DNS) or Distributed Hash Tables
   (DHTs) could be used to find a neighbor that provides an inter-
   planetary gateway.  Such advanced rendezvous schemes are beyond the
   scope of this document.

   In contrast, DTN-IPND is designed to be DTN-specific, efficient, and
   extremely lightweight.  For instance, DTN-IPND is capable of
   supporting arbitrary length DTN EIDs, and includes CLA information in
   order to maximize the utility of each beacon message without
   requiring multiple round-trip times in order to perform complex
   protocol negotiation.

   While DTN-IPND MAY be used in non-DTN environments, its use is
   RECOMMENDED only in DTNs.



























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4.  Implementation Experience

   BBN Technologies has implemented and deployed DTN IPND as part of the
   SPINDLE [SPINDLE] project.















































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5.  Security Considerations

   Neighbor discovery may be perceived as an impediment to security
   because it advertises a potential target for attacks.  Discovering
   the existence of a particular node is orthogonal to securing the
   services of that node.  Nodes that desire or require higher-levels of
   security SHOULD disable the broadcast IPND beacons and rely instead
   on static neighbor configuration.

   Further, neighbor discovery represents a potential source of network
   congestion and contention.  Therefore, careful consideration should
   be made to the frequency and TTL scope of beacons when setting
   implementation-specific parameters, particularly when a setting
   affects larger regions of the network.





































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6.  IANA Considerations

   None at this time.
















































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7.  References

7.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, January 2005.

7.2.  Informative References

   [BONJOUR]  Cheshire, S., "Bonjour", Apr 2005.

   [NHDP]     Clausen, T., Dearlove, C., and J. Dean, "MANET
              Neighborhood Discovery Protocol (NHDP)", Mar 2009.

   [PROPHET]  Lindgren, A. and A. Doria, "Probabilistic Routing Protocol
              for Intermittently  Connected Networks", Mar 2006.

   [RFC1112]  Deering, S., "Host extensions for IP multicasting", STD 5,
              RFC 1112, August 1989.

   [RFC3171]  Albanna, Z., Almeroth, K., Meyer, D., and M. Schipper,
              "IANA Guidelines for IPv4 Multicast Address Assignments",
              BCP 51, RFC 3171, August 2001.

   [RFC3376]  Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A.
              Thyagarajan, "Internet Group Management Protocol, Version
              3", RFC 3376, October 2002.

   [RFC3927]  Cheshire, S., Aboba, B., and E. Guttman, "Dynamic
              Configuration of IPv4 Link-Local Addresses", RFC 3927,
              May 2005.

   [RFC4838]  Cerf, V., Burleigh, S., Hooke, A., Torgerson, L., Durst,
              R., Scott, K., Fall, K., and H. Weiss, "Delay-Tolerant
              Networking Architecture", RFC 4838, April 2007.

   [RFC5050]  Scott, K. and S. Burleigh, "Bundle Protocol
              Specification", RFC 5050, November 2007.

   [SDNV]     Eddy, W., "Using Self-Delimiting Numeric Values in
              Protocols", Jan 2009.

   [SPINDLE]  Krishnan, R., "Survivable Policy-Influenced Networking:
              Disruption-tolerance through Learning and Evolution",



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              Oct 2006.

   [TCPCLA]   Demmer, M. and J. Ott, "Delay Tolerant Networking TCP
              Convergence Layer Protocol", Nov 2008.

   [UDPCLA]   Kruse, H. and S. Ostermann, "UDP Convergence Layers for
              the DTN Bundle and LTP Protocols", Nov 2008.












































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Internet-Draft                  DTN-IPND                      March 2010


Authors' Addresses

   Daniel Ellard
   Raytheon BBN Technologies
   10 Moulton St.
   Cambridge, MA  02138
   US

   Email: dellard@bbn.com


   Daniel Brown
   Raytheon BBN Technologies
   10 Moulton St.
   Cambridge, MA  02138
   US

   Email: dbrown@bbn.com

































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