Subject: [manet] draft-boot-manet-nemo-analysis-00.txt

From: "Teco Boot" <[email-masked]>
Date: Tue, 27 Feb 2007 09:02:49 +0100

<copy 3rd time; submit on MANET WG as it was rejected the 1st & 2nd time>
[Teco] Now shortened somewhat for keeping within size limits
-----Original Message-----
From: Teco Boot
Sent: maandag 26 februari 2007 14:16
To: 'Jari Arkko'
Cc: [email-masked]'; [email-masked]'; [email-masked]'
Subject: draft-boot-manet-nemo-analysis-00.txt

Hi Jari,

I finished writing an I-D with an analysis of MANET and NEMO. It can be used
as background information, for MANET and NEMO WG meetings in Prague. I
included I-D text below in advance.

Others are working on improving the MANEMO problem statement / writing other
I-Ds on this subject.

Regards, Teco

=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+

MANET and NEMO Working Groups                                    T. Boot
Internet-Draft                                         Infinity Networks
Expires: August 30, 2007                               February 26, 2007

                       Analysis of MANET and NEMO
                 draft-boot-manet-nemo-analysis-00.txt

Abstract

   This document provides an overview of MANET and NEMO characteristics.
   It is claimed that MANET suits small mobile network topologies,
   providing optimal paths for communication within a MANET cloud.  It
   is also claimed that NEMO suits small, mobile networks, providing
   sub-optimal paths to all Internet connected nodes.  MANET and NEMO
   technology shortcoming are described, to be addressed in the MANET
   and NEMO workgroups or elsewhere within the IETF.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3

   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4

   3.  MANET and NEMO Characteristics . . . . . . . . . . . . . . . .  6
     3.1.  Scalability  . . . . . . . . . . . . . . . . . . . . . . .  6
     3.2.  Mobility . . . . . . . . . . . . . . . . . . . . . . . . .  6
     3.3.  HA dependency  . . . . . . . . . . . . . . . . . . . . . .  7
     3.4.  Route optimization . . . . . . . . . . . . . . . . . . . .  7
     3.5.  Interface type . . . . . . . . . . . . . . . . . . . . . .  7
     3.6.  Multicast support  . . . . . . . . . . . . . . . . . . . .  8
     3.7.  Worst Path First Syndrome  . . . . . . . . . . . . . . . .  8

   4.  MANET for NEMO . . . . . . . . . . . . . . . . . . . . . . . . 11

   5.  IANA considerations  . . . . . . . . . . . . . . . . . . . . . 12

   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 13

   7.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 14

   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
     8.1.  Normative reference  . . . . . . . . . . . . . . . . . . . 14
     8.2.  Informative Reference  . . . . . . . . . . . . . . . . . . 15

   Appendix A.  Change Log From Previous Version  . . . . . . . . . . 16

   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 16
   Intellectual Property and Copyright Statements . . . . . . . . . . 17

1.  Introduction

   IP technology is increasingly being used in mobile networks.  Many
   issues arise with mobility, for example wireless bandwidth and link
   quality are typically low related to fixed, wired infrastructures.
   Also routing protocols for mobile environments are faced with new
   challenges; connectivity comes and goes when nodes move and link
   quality increases and decreases instead of flapping between an OK and
   an NOT-OK state.

   Two IETF mobility technologies are available, that is Mobile Ad-hoc
   NETworks (MANET) and Mobile IP (MIP).

   The MANET workgroup is working on routing protocols, running on
   mobile or fixed routers; either in small isolated topologies or at
   edges of large IP infrastructures.  Multiple types of MANET protocols
   exist; OLSR [1] is a proactive MANET protocol populating the routing
   table independent of any user traffic; DYMO [2] is a reactive
   protocol, providing path information for traffic flows and SMF [3] is
   a multicast flooding protocol.

   The MIP4 and MIP6 workgroups are working on mobility support for
   hosts, enabling session continuity while moving.  Other workgroups
   are working on improvements on MIP, for example MONAMI6 and MIPSHOP
   are working on using multiple interfaces towards the IP
   infrastructure.  The NEMO workgroup extends MIP using the Mobile
   Router concept, providing MIP services for MR attached nodes.  With
   NEMO, nesting can occur, introducing new challenges.

   Currently, a number of communities are working on network
   architectures for mobile domains.  Different communities work on
   different domains, all having their specific requirements.  Work
   within the IETF would comply with all those requirements.  Sample
   domains are military, public safety / emergency response networks,
   mobile networks used by enterprises and non-governmental
   organizations, provider based Internet access, license-free wireless
   networks and networks for intelligent transport systems / vehicle
   communication systems.  Also combinations of multiple domains can be
   used, for example a mobile network for a disaster relief organization
   could use own licensed transmission means, provider based Internet
   access and license-free wireless networks; all used in cars also
   equipped with an inter-vehicle communication system / intelligent
   transport system.

2.  Terminology

   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 RFC2119 [4]

   Readers are expected to be familiar with all the terms defined in
   RFC3753: Mobility Related Terminology [5] and the NEMO Terminology
   draft [6]

   MANET

      Mobile Ad-hoc NETworks [5]

   NEMO

      NEtork MObility [6]

   NEMO BS

      Network Mobility Basic Support Protocol [7]

   NEMO RO

      NEMO Route Optimization [8] / [9] / [20]

   MIP

      Mobile IP [6]

   MIP4

      IP Mobility Support for IPv4 [10]

   MIP6

      Mobility Support in IPv6 [11]

   OLSR

      Optimized Link-State Routing Protocol [1]

   DYMO

      Dynamic MANET On-demand Routing [2]

   SMF

      Simplified Multicast Forwarding for MANET [3]

   OSPF

      Open Shortest Path First [12][13]

   MONAMI6

      Mobile Nodes and Multiple Interfaces in IPv6

   MIPSHOP

      Mobility for IP: Performance, Signaling and Handoff Optimization

   HAHA

      Global HA to HA protocol [14]; [15]

   MR

      Mobile Router [5] [6]; also referenced as "MANET Router"[16]

   HA

      Home Agent [6]

   CN

      Correspondent Node [6]

   LFN

      Local Fixed Node [6]

   RA

      Router Advertisement [17]

3.  MANET and NEMO Characteristics

3.1.  Scalability

   MANET and NEMO have very different scalability characteristics.
   MANET can provide optimized paths within a limited topology, where
   NEMO provides Internet scale end-to-end connectivity.

   MANET scalability is researched and many improvements are proposed.
   But still MANET networks have their limits, a large number (100 or
   more) of Mobile Routers in a flat area is a topic for active research
   [16].  Other technology must be used to provide Internet scale
   deployment.

   The OSPF MANET extension [21], [22] is applicable for a limited
   number of routers interconnected with radio interfaces.  Such a MANET
   subnetwork would be part of an OSPF area, and OSPF (and BGP) routing
   state flooding reduction mechanisms enable large scale deployment.
   Many independent OSPF MANET subnetworks can de deployed, similar to
   for example Ethernet segment scalability.

   NEMO makes use of the MIP tunnel overlay, hiding mobility on the
   fixed Internet infrastructure.  The number of mobile networks scales
   with the number of home agents, and address aggregation enables huge
   scale NEMO deployment.

3.2.  Mobility

   With MANET, a MR can roam within an area where sufficient coverage is
   available.  When the number of MRs increase, coverage will improve or
   the area will be enlarged.  Scalability issues restrict the number of
   MRs, which implies restrictions on mobility.  Zoned or hierarchical
   models are proposed, but world wide mobility would not be provided by
   MANET.

   With NEMO, scalability is not an issue and worldwide mobility can be
   provided for an almost unlimited number of MR, all having end-to-end
   connectivity.

   For both MANET and NEMO, mobility is related to radio coverage.  No
   coverage implies no connectivity.  Wireless Bandwidth is a scarce
   resource, so an ad-hoc dense crowd of MR requiring lots of bandwidth
   will overload available transmission means.  Mobility is thus also
   restricted by available bandwidth.

3.3.  HA dependency

   MANET does not depend on Mobile IP and doesn't need a home agent.

   NEMO extends Mobile IP using a Mobile Router.  The Mobile Router
   maintains a tunnel to its home agent.  Traffic between LFN and CN
   flows through the tunnel and thus the home agent is a critical
   element for communication.  HA dependency can be relaxed by HA
   redundancy or new protocols, like Global HA to HA protocol (HAHA)
   [14] / [15].  MIP and NEMO Route Optimization could also relax the HA
   dependency.

   For communication from a NEMO LFN to a far away CN, the HA dependency
   may not be a problem.  But for local communication, this could be
   unacceptable, especially in military and public safety / emergency
   response networks, where local communication availability is a
   primary concern.

3.4.  Route optimization

   MANET protocols would select a shortest path (fewest hops, lowest
   metric) or an optimized path based on cross-layer metrics.  Problems
   with optimized path selection based on fewest hop count are described
   below in section Worst Path First Syndrome.

   Currently, nested NEMO based on NEMO BS [7] lacks intelligent path
   selection.  RA sent by MR are equivalent to RA sent by a fixed Access
   Router.  Selecting an Attachement Router without any knowledge on
   path metrics would select non-optimal paths.  Nested NEMO has high
   tunnel header overhead and a pinball route problem.  Also route loops
   can occur (NEMO RO) [8]

3.5.  Interface type

   In the MANET architecture, a MANET-Interface is an interface with a
   MANET protocol enabled.  Typical behavior is the relay function,
   incoming traffic on this interface can be relayed to serve other
   nodes increasing connectivity in the MANET topology [18].

   In Mobility Related Terminology [5], The Ingress and Egress Interface
   types are introduced.  Terms are related to the NEMO mobile Router
   model [7].  The Ingress Interface is the interface with the Mobile
   Network Nodes connected to.  The Egress Interface is the interface
   the Mobile Router uses to attach to the fixed infrastructure.

   When discussions started about integrating MANET and NEMO, the
   difference between the MANET and Egress interface faded.  Also a
   discussion about the need for a MANEMO Ingress Interfaces started, as

   in MANET there is no need for special handling, and in MANEMO any MR
   interface could be MANET enabled.  For policy reasons, a MANEMO
   interface could be defined as Ingress only.

3.6.  Multicast support

   In MANET environment, classical multicast forwarding using a Reverse
   Path Forwarding Check cannot be used.  The MANET interface is used
   for relaying IP packets, and a basic forwarding rule is broken,
   specifying that an IP multicast packet is never sent back over the
   incoming interface.

   Multiple MANET multicast protocols are proposed, but many of them
   showed large overhead for keeping state information.  Currently the
   MANET workgroup is working on SMF [3].  SMF use 2-hop neighbor state
   provided by another protocol (currently NHDP [19]) for efficient
   flooding combined with duplicate packet detection.

   In NEMO, multicast service can be provided.  Within the Mobile
   Network itself, basic multicasting is used.  Global multicast
   supported can also be provided; the MR relays the multicast to the
   HA, where the multicast flow is injected in the fixed infrastructure.
   Receiving multicast from the fixed infrastructure is also supported,
   the HA relays the multicast flow via the tunnel to the MR and the
   FLNs.

   Multicasting between nearby NEMO MRs would have large overhead, as
   the multicast is lead over the HAs.  Also multicast from the fixed
   infrastructure to multiple nearby NEMO MRs is inefficient, as the
   multicast flow is pseudo-broadcasted over multiple tunnels to these
   MRs.  Options for improved NEMO multicast support are proposed, e.g.
   using MLD-proxy [23].

3.7.  Worst Path First Syndrome

   Classic routing protocols use the hop-count as metric for best path
   selecting.  Hop-count is still used in modern MANET routing
   protocols.  For homogeneous topologies, where all links have similar
   capabilities, this could be seen as sufficient.  But when different
   link types are used or link characteristics vary in time and on a
   neighbor by neighbor basis, problems are introduced.  Using cross-
   layer information is seen as helpful for MANET environments[16].

   NEMO / nested NEMO do not select a path based on metrics.

   The Worst Path First Syndrome is a name given to a behavior of a path
   selection algorithm, selecting the path to a destination using the
   fewest hops, but also the worst quality links.  Using ad-hoc networks
   with broadcast radios, link quality and data rate would be a function
   of distance and influenced by obstacles.  In the example below, a
   high quality radio link uses a data rate of 11Mbps and has a packet
   loss below 1%.  A bad quality radio link uses a data rate of 1Mbps
   and has a packet loss around 50%.

               +-----+
               | MR1 |
               +-----+
         11Mbps /  |
         loss  /   |
         <1%  /    | 1Mbps
            +-+-+  | loss ~50%
            |MR2|  |
            +-+-+  |
        11Mbps \   |
           loss \  |
             <1% \ |
                 +-+-+
                 |MR3|
                 +---+

           Figure 1: Worst Path First Syndrome Network Topology

   MR3 can select MR1 or MR2 as attachment router, router advertisements
   from both MR1 and MR2 are received.  A MANET protocol, selecting a
   path based on hop-count, selects the direct path to MR1.  NEMO would
   select MR1 or MR2, as it has no knowledge of the topology.

   Selecting the direct path to MR1 is the worst in terms of bandwidth
   (1Mbps where 11Mbps is available), packet loss (50% where less than
   2% is available) and used spectrum (single transmission over 1Mbps
   takes more time for sending a packet than 2 times over 11Mbps).  The
   direct path to MR1 would require more retransmissions if reliable
   data transfer is supported.

   In a heterogeneous topology, the problem becomes totally
   unacceptable.  Imagine that the three MRs are temporally "on the
   pause" and MR2 and MR3 are near to each other.  Because MR3 has bad
   user experience, it can be serviced by using cabling to MR2 and the
   bandwidth is increased to 100Mbps and the packet loss is zero.
   Still, user experience is not enhanced at all, and MR1 would be
   selected.

   Finding solutions for this problem is out of scope of this document.
   But state of the art MANET protocols, including MANEMO if this work-
   in-progress is continued, shall select optimized paths based on cross
   layer metrics.

4.  MANET for NEMO

   A MANEMO design team is working on a MANET for NEMO.  This MANET
   protocol is used as an enhancement on NEMO, solving problems with
   nested NEMO.  It also introduces scalability in MANET as it
   introduces a new hierarchical layer by using Mobile IP / NEMO.
   MANEMO can be used where fixed infrastructures are partly available
   and where local communication between MRs is a basic requirement.
   Also multicast support and usage of cross-layer metrics is in scope
   for MANEMO.

   The MANEMO protocol is introduced in the MANEMO Problem Statement
   document [24].

8.  References

8.1.  Normative reference

   [1]   Clausen, T., "The Optimized Link-State Routing Protocol version
         2", draft-ietf-manet-olsrv2-02 (work in progress), June 2006.

   [2]   Perkins, C. and I. Chakeres, "Dynamic MANET On-demand (DYMO)
         Routing", draft-ietf-manet-dymo-06 (work in progress),
         October 2006.

   [3]   Macker, J., "Simplified Multicast Forwarding for MANET",
         draft-ietf-manet-smf-03 (work in progress), October 2006.

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

   [5]   Manner, J. and M. Kojo, "Mobility Related Terminology",
         RFC 3753, June 2004.

   [6]   Ernst, T. and H. Lach, "Network Mobility Support Terminology",
         draft-ietf-nemo-terminology-06 (work in progress),
         November 2006.

   [7]   Devarapalli, V., Wakikawa, R., Petrescu, A., and P. Thubert,
         "Network Mobility (NEMO) Basic Support Protocol", RFC 3963,
         January 2005.

   [8]   Ng, C., "Network Mobility Route Optimization Problem
         Statement", draft-ietf-nemo-ro-problem-statement-03 (work in
         progress), September 2006.

   [9]   Ng, C., "Network Mobility Route Optimization Solution Space
         Analysis", draft-ietf-nemo-ro-space-analysis-03 (work in
         progress), September 2006.

   [10]  Perkins, C., "IP Mobility Support for IPv4", RFC 3344,
         August 2002.

   [11]  Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in
         IPv6", RFC 3775, June 2004.

   [12]  Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.

   [13]  Coltun, R., Ferguson, D., and J. Moy, "OSPF for IPv6",
         RFC 2740, December 1999.

   [14]  Thubert, P., "Global HA to HA protocol",
         draft-thubert-nemo-global-haha-02 (work in progress),
         September 2006.

   [15]  Devarapalli, V., "Local HA to HA protocol",
         draft-devarapalli-mip6-nemo-local-haha-01 (work in progress),
         March 2006.

   [16]  Chakeres, I., "Mobile Ad hoc Network Architecture",
         draft-chakeres-manet-arch-01 (work in progress), October 2006.

   [17]  Narten, T., Nordmark, E., and W. Simpson, "Neighbor Discovery
         for IP Version 6 (IPv6)", RFC 2461, December 1998.

   [18]  Templin, F., "Observations on "Link" in MANET/Autoconf and
         Other Contexts", draft-templin-manet-autoconf-link-00 (work in
         progress), August 2006.

   [19]  Clausen, T., "MANET Neighborhood Discovery Protocol (NHDP)",
         draft-ietf-manet-nhdp-00 (work in progress), June 2006.

8.2.  Informative Reference

   [20]  Clausen, T., Baccelli, E., and R. Wakikawa, "NEMO Route
         Optimisation Problem Statement",
         draft-clausen-nemo-ro-problem-statement-00 (work in progress),
         October 2004.

   [21]  Spagnolo, P. and R. Ogier, "MANET Extension of OSPF using CDS
         Flooding", draft-ogier-manet-ospf-extension-08 (work in
         progress), October 2006.

   [22]  Roy, A. and M. Chandra, "Extensions to OSPF to Support Mobile
         Ad Hoc Networking", draft-chandra-ospf-manet-ext-04 (work in
         progress), January 2007.

   [23]  Janneteau, C., "IPv6 Multicast for Mobile Networks with MLD-
         Proxy", draft-janneteau-nemo-multicast-mldproxy-00 (work in
         progress), April 2004.

   [24]  Wakikawa, R. and P. Thubert, "MANEMO Problem Statement",
         draft-wakikawa-manemo-problem-statement-00 (work in progress),
         February 2007.

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