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Versions: (draft-manyfolks-gaia-community-networks) 00 01 02 03 04 05 06 07 08 RFC 7962

Global Access to the Internet for All                    J. Saldana, Ed.
Internet-Draft                                    University of Zaragoza
Intended status: Informational                            A. Arcia-Moret
Expires: January 2, 2016                         University of Cambridge
                                                                B. Braem
                                                                  iMinds
                                                         E. Pietrosemoli
                                                                    ICTP
                                                         A. Sathiaseelan
                                                 University of Cambridge
                                                              M. Zennaro
                                                        Abdus Salam ICTP
                                                            July 1, 2015


     Alternative Network Deployments.  Taxonomy, characterization,
                     technologies and architectures
           draft-irtf-gaia-alternative-network-deployments-01

Abstract

   This document presents a taxonomy of "Alternative Network
   deployments", and a set of definitions and shared properties.  It
   also discusses the technologies employed in these network
   deployments, and their differing architectural characteristics.

   The term "Alternative Network Deployments" includes a set of network
   access models that have emerged in the last decade with the aim of
   bringing Internet connectivity to people, using topological,
   architectural and business models different from the so-called
   "traditional" ones, where a company deploys or leases the network
   infrastructure for connecting the users, who pay a subscription fee
   to be connected and make use of it.

   Several initiatives throughout the world have built large scale
   alternative Networks, using predominantly wireless technologies
   (including long distance) due to the reduced cost of using the
   unlicensed spectrum.  Wired technologies such as fiber are also used
   in some of these alternate networks.  There are several types of
   alternate networks: community networks, which are self-organized and
   decentralized networks wholly owned by the community; networks owned
   by individuals who act as wireless internet service providers
   (WISPs); networks owned by individuals but leased out to network
   operators who use them as a low-cost medium to reach the underserved
   population, and finally there are networks that provide connectivity
   by sharing wireless resources of the users.





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   The emergence of these networks can be motivated by different causes
   such as the reluctance, or the impossibility, of network operators to
   provide wired and cellular infrastructures to rural/remote areas.  In
   these cases, the networks have self sustainable business models that
   provide more localized communication services as well as Internet
   backhaul support through peering agreements with traditional network
   operators.  Some other times, networks are built as a complement and
   an alternative to commercial Internet access provided by
   "traditional" network operators.

   The present classification considers different existing network
   models such as Community Networks, open wireless services, user-
   extensible services, traditional local Internet Service Providers
   (ISPs), new global ISPs, etc.  Different criteria are used in order
   to build a classification as e.g., the ownership of the equipment,
   the way the network is organized, the participatory model, the
   extensibility, if they are driven by a community, a company or a
   local stakeholder (public or private), etc.

   According to the developed taxonomy, a characterization of each kind
   of network is presented in terms of specific network characteristics
   related to architecture, organization, etc.

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Internet-Drafts are draft documents valid for a maximum of six months
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   This Internet-Draft will expire on January 2, 2016.

Copyright Notice

   Copyright (c) 2015 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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   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
     1.1.  Traditional networks  . . . . . . . . . . . . . . . . . .   5
     1.2.  Criteria for the classification of Alternative Networks .   5
       1.2.1.  Commercial model / promoter . . . . . . . . . . . . .   5
       1.2.2.  Goals and motivation  . . . . . . . . . . . . . . . .   6
       1.2.3.  Administrative model  . . . . . . . . . . . . . . . .   6
       1.2.4.  Technologies employed . . . . . . . . . . . . . . . .   6
       1.2.5.  Typical scenarios . . . . . . . . . . . . . . . . . .   7
   2.  Classification of Alternative Networks  . . . . . . . . . . .   7
     2.1.  Community Networks  . . . . . . . . . . . . . . . . . . .   7
       2.1.1.  Free Networks . . . . . . . . . . . . . . . . . . . .   9
     2.2.  Wireless Internet Service Providers WISPs . . . . . . . .  10
     2.3.  Shared infrastructure model . . . . . . . . . . . . . . .  11
     2.4.  Crowdshared approaches, led by the people and third party
           stakeholders  . . . . . . . . . . . . . . . . . . . . . .  12
     2.5.  Testbeds for research purposes  . . . . . . . . . . . . .  15
   3.  Scenarios where Alternative Networks are deployed . . . . . .  15
     3.1.  Digital Divide and Alternative Networks . . . . . . . . .  15
     3.2.  Urban vs. rural areas . . . . . . . . . . . . . . . . . .  17
     3.3.  Gap between demanded and provided communications services  18
     3.4.  Topology patterns followed by Alternative Networks  . . .  18
   4.  Technologies employed . . . . . . . . . . . . . . . . . . . .  19
     4.1.  Wired . . . . . . . . . . . . . . . . . . . . . . . . . .  19
     4.2.  Wireless  . . . . . . . . . . . . . . . . . . . . . . . .  19
       4.2.1.  Antennas  . . . . . . . . . . . . . . . . . . . . . .  19
       4.2.2.  Physical link length  . . . . . . . . . . . . . . . .  20
         4.2.2.1.  Line-of-Sight . . . . . . . . . . . . . . . . . .  20
         4.2.2.2.  Transmitted and Received Power  . . . . . . . . .  20
       4.2.3.  Media Access Control (MAC) Protocols for Wireless
               Links . . . . . . . . . . . . . . . . . . . . . . . .  21
         4.2.3.1.  802.11 (Wi-Fi)  . . . . . . . . . . . . . . . . .  21
         4.2.3.2.  GSM . . . . . . . . . . . . . . . . . . . . . . .  23
         4.2.3.3.  Dynamic Spectrum  . . . . . . . . . . . . . . . .  23
   5.  Upper layers  . . . . . . . . . . . . . . . . . . . . . . . .  24
     5.1.  Layer 3 . . . . . . . . . . . . . . . . . . . . . . . . .  24
       5.1.1.  IP addressing . . . . . . . . . . . . . . . . . . . .  24
       5.1.2.  Routing protocols . . . . . . . . . . . . . . . . . .  25
         5.1.2.1.  Traditional routing protocols . . . . . . . . . .  25
         5.1.2.2.  Mesh routing protocols  . . . . . . . . . . . . .  25



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     5.2.  Transport layer . . . . . . . . . . . . . . . . . . . . .  26
       5.2.1.  Traffic Management when sharing network resources . .  26
       5.2.2.  Multi-hop issues  . . . . . . . . . . . . . . . . . .  26
     5.3.  Services provided . . . . . . . . . . . . . . . . . . . .  27
       5.3.1.  Intranet services . . . . . . . . . . . . . . . . . .  27
       5.3.2.  Access to the Internet  . . . . . . . . . . . . . . .  28
         5.3.2.1.  Web browsing proxies  . . . . . . . . . . . . . .  28
         5.3.2.2.  Use of VPNs . . . . . . . . . . . . . . . . . . .  28
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  28
   7.  Contributing Authors  . . . . . . . . . . . . . . . . . . . .  28
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  30
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  30
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  30
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  30
     10.2.  Informative References . . . . . . . . . . . . . . . . .  31
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  36

1.  Introduction

   Several initiatives throughout the world have built large scale
   networks that are alternative to the traditional network operator
   deployments using predominantly wireless technologies (including long
   distance) due to the reduced cost of using the unlicensed spectrum.
   Wired technologies such as fiber are also used in some of these
   alternate networks.  There are several types of alternate
   deployments: community networks are self-organized and decentralized
   networks wholly owned by the community; networks owned by individuals
   who act as wireless internet service providers (WISPs); networks
   owned by individuals but leased out to network operators who use such
   networks as a low cost medium to reach the underserved population,
   and finally there are networks that provide connectivity by sharing
   wireless resources of the users.

   The emergence of these networks can be motivated by different causes,
   as the reluctance, or the impossibility, of network operators to
   provide wired and cellular infrastructures to rural/remote areas
   [Pietrosemoli].  In these cases, the networks have self sustainable
   business models that provide more localized communication services as
   well as Internet backhaul support (i.e. uplink connection) through
   peering agreements with traditional network operators.  Some other
   times, they are built as a complement and an alternative to
   commercial Internet access provided by "traditional" network
   operators.

   One of the aims of the Global Access to the Internet for All (GAIA)
   IRTF initiative is "to document and share deployment experiences and
   research results to the wider community through scholarly
   publications, white papers, Informational and Experimental RFCs,



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   etc."  In line with this objective, this document is intended to
   propose a classification of these "Alternative Network Deployments".
   This term includes a set of network access models that have emerged
   in the last decade with the aim of bringing Internet connectivity to
   people, following topological, architectural and business models
   different from the so-called "traditional" ones, where a company
   deploys the infrastructure connecting the users, who pay a
   subscription fee to be connected and make use of it.  The document is
   intended to be largely descriptive providing a broad overview of
   initiatives, technologies and approaches employed in these networks.
   Research references describing each kind of network are also
   provided.

1.1.  Traditional networks

   In this document we will use the term "traditional networks" to
   denote those sharing these characteristics:

   - Regarding scale, they are usually large networks spanning entire
   regions.

   - Top-down control of the network and centralized approaches are
   used.

   - They require a substantial investment in infrastructure.

   - Users in traditional networks tend to be passive consumers, as
   opposed to active stakeholders, in the network design, deployment,
   operation and maintenance.

1.2.  Criteria for the classification of Alternative Networks

   The classification of Alternative Network Deployments, presented in
   this document, is based on the next criteria:

1.2.1.  Commercial model / promoter

   The entity (or entities) or individuals promoting an Alternative
   Network can be:

   o  a community of users

   o  a public stakeholder

   o  a private company

   o  crowdshared approaches are also considered




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   o  shared infrastructure

   o  they can be created as a testbed by a research or academic entity

1.2.2.  Goals and motivation

   Alternative networks can also be classified according to the
   underlying motivation for them, i.e., addressing deployment and usage
   hurdles:

   o  reducing initial capital expenditures (for the network and the end
      user, or both)

   o  providing additional sources of capital (beyond the traditional
      carrier-based financing)

   o  reducing on-going operational costs (such as backhaul or network
      administration)

   o  leveraging expertise

   o  reducing hurdles to adoption (digital literacy; literacy, in
      general; relevance, etc.)

   o  extending coverage to underserved areas (users and communities)

   o  network neutrality guarantees

1.2.3.  Administrative model

   o  centralized

   o  distributed

1.2.4.  Technologies employed

   o  normal Wi-Fi

   o  Wi-Fi modified for long distances (WiLD), either with CSMA/CA or
      with an alternative TDMA MAC [Simo_b]

   o  802.16-compliant systems over non-licensed bands

   o  Dynamic Spectrum Solutions (e.g. based on the use of white spaces)

   o  satellite solutions

   o  low-cost optical fiber systems



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1.2.5.  Typical scenarios

   The scenarios where Alternative Networks are usually deployed can be:

   o  urban

   o  rural

   o  rural in developing countries

2.  Classification of Alternative Networks

   This section classifies Alternative Networks (ANs) according to their
   intended usage.  Each of them has different incentive structures,
   maybe common technological challenges, but most importantly
   interesting usage challenges which feeds into the incentives as well
   as the technological challenges.

   At the beginning of each subsection, a table is presented including a
   classification of each network according to the criteria listed in
   the "Criteria for the classification of Alternative Networks"
   subsection.

2.1.  Community Networks

   +--------------------+----------------------------------------------+
   | Commercial         | community                                    |
   | model/promoter     |                                              |
   +--------------------+----------------------------------------------+
   | Goals and          | reducing hurdles; to serve underserved       |
   | motivation         | areas; network neutrality                    |
   +--------------------+----------------------------------------------+
   | Administration     | distributed                                  |
   +--------------------+----------------------------------------------+
   | Technologies       | Wi-Fi, optical fiber                         |
   +--------------------+----------------------------------------------+
   | Typical scenarios  | urban and rural                              |
   +--------------------+----------------------------------------------+

           Table 1: Community Networks' characteristics summary

   Community Networks are large-scale, distributed, self-managed
   networks sharing these characteristics:

   - They are built and organized in a decentralized and open manner.

   - They start and grow organically, they are open to participation
   from everyone, sometimes sharing an open peering agreement.



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   Community members directly contribute active (not just passive)
   network infrastructure.

   - Knowledge about building and maintaining the network and ownership
   of the network itself is decentralized and open.  Community members
   have an obvious and direct form of organizational control over the
   overall operation of the network in their community (not just their
   own participation in the network).

   - The network can serve as a backhaul for providing a whole range of
   services and applications, from completely free to even commercial
   services.

   Hardware and software used in Community Networks can be very diverse,
   even inside one network.  A Community Network can have both wired and
   wireless links.  Multiple routing protocols or network topology
   management systems may coexist in the network.

   These networks grow organically, since they are formed by the
   aggregation of nodes belonging to different users.  A minimum
   governance infrastructure is required in order to coordinate IP
   addressing, routing, etc.  An example of this kind of Community
   Network is described in [Braem].  These networks follow a
   participatory model, which has been shown effective in connecting
   geographically dispersed people, thus enhancing and extending digital
   Internet rights.

   The fact of the users adding new infrastructure (i.e. extensibility)
   can be used to formulate another definition: A Community Network is a
   network in which any participant in the system may add link segments
   to the network in such a way that the new segments can support
   multiple nodes and adopt the same overall characteristics as those of
   the joined network, including the capacity to further extend the
   network.  Once these link segments are joined to the network, there
   is no longer a meaningful distinction between the previous and the
   new extent of the network.

   In Community Networks, the profit can only be made by services and
   not by the infrastructure itself, because the infrastructure is
   neutral, free, and open (traditional Internet Service Providers,
   ISPs, base their business on the control of the infrastructure).  In
   Community Networks, everybody keeps the ownership of what he/she has
   contributed.

   Community Networks may also be called "Free Networks" or even
   "Network Commons" [FNF].  The majority of Community Networks
   accomplishes the definition of Free Network, included in the next
   subsection.



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2.1.1.  Free Networks

   A definition of Free Network (which may be the same as Community
   Network) is proposed by the Free Network Foundation (see
   http://thefnf.org) as:

   "A free network equitably grants the following freedoms to all:

   Freedom 0 - The freedom to communicate for any purpose, without
   discrimination, interference, or interception.

   Freedom 1 - The freedom to grow, improve, communicate across, and
   connect to the whole network.

   Freedom 2- The freedom to study, use, remix, and share any network
   communication mechanisms, in their most reusable forms."

   The principles of Free, Open and Neutral Networks have also been
   summarized (see http://guifi.net/en/FONCC) this way:

   - You have the freedom to use the network for any purpose as long as
   you do not harm the operation of the network itself, the rights of
   other users, or the principles of neutrality that allow contents and
   services to flow without deliberate interference.

   - You have the right to understand the network, to know its
   components, and to spread knowledge of its mechanisms and principles.

   - You have the right to offer services and content to the network on
   your own terms.

   - You have the right to join the network, and the responsibility to
   extend this set of rights to anyone according to these same terms.


















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2.2.  Wireless Internet Service Providers WISPs

   +--------------------+----------------------------------------------+
   | Commercial         | company                                      |
   | model/promoter     |                                              |
   +--------------------+----------------------------------------------+
   | Goals and          | to serve underserved areas; to reduce CAPEX  |
   | motivation         | in Internet access                           |
   +--------------------+----------------------------------------------+
   | Administration     | centralized                                  |
   +--------------------+----------------------------------------------+
   | Technologies       | wireless, unlicensed frequencies             |
   +--------------------+----------------------------------------------+
   | Typical scenarios  | rural                                        |
   +--------------------+----------------------------------------------+

                  Table 2: WISPs' characteristics summary

   WISPs are commercially-operated wireless Internet networks that
   provide Internet and/or Voice Over Internet (VoIP) services.  They
   are most common in areas not covered by incumbent telcos or ISPs.
   WISPs often use wireless point-to-point or point-to-multipoint in the
   unlicensed frequencies but licensed frequency use is common too
   especially in regions where unlicensed spectrum is either perceived
   as crowded or where unlicensed spectrum may have regulatory barriers
   impeding its use.

   Most WISPs are operated by local companies responding to a perceived
   market gap.  There is a small but growing number of WISPs, such as
   AirJaldi [Airjaldi] in India that have expanded from local service
   into multiple locations.

   Since 2006, the deployment of cloud-managed WISPs has been possible
   with companies like Meraki and later OpenMesh and others.  Until
   recently, however, most of these services have been aimed at
   industrialized markets.  Everylayer [Everylayer], launched in 2014,
   is the first cloud-managed WISP service aimed at emerging markets.














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2.3.  Shared infrastructure model

   +----------------+--------------------------------------------------+
   | Commercial     | shared: companies and users                      |
   | model/promoter |                                                  |
   +----------------+--------------------------------------------------+
   | Goals and      | to eliminate a CAPEX barrier (to operators);     |
   | motivation     | lower the OPEX (supported by the community); to  |
   |                | extend coverage to underserved areas             |
   +----------------+--------------------------------------------------+
   | Administration | distributed                                      |
   +----------------+--------------------------------------------------+
   | Technologies   | wireless in non-licensed bands and/or low-cost   |
   |                | fiber                                            |
   +----------------+--------------------------------------------------+
   | Typical        | rural areas, and more particularly rural areas   |
   | scenarios      | in developing regions                            |
   +----------------+--------------------------------------------------+

          Table 3: Shared infrastructure characteristics summary

   In conventional networks, the operator usually owns the
   telecommunications infrastructures required for the service, or
   sometimes rents these infrastructures to other companies.  The
   problem arises in large areas with low population density, in which
   neither the operator nor other companies have deployed infrastructure
   and such deployments are not likely to happen due to the low
   potential return of investment.

   When users already own a deployed infrastructure, either individually
   or as a community, sharing that infrastructure with an operator
   represents an interesting win-win solution that starts to be
   exploited in some contexts.  For the operator, this supposes a
   significant reduction of the initial investment needed to provide
   services in small rural localities because the CAPEX is only
   associated to the access network, as renting capacity in the users'
   network for backhauling supposes is only an increment in the OPEX.
   This approach also benefits the users in two ways: they obtain
   improved access to telecommunications services that would not be
   otherwise accessible, and they can get some income from the operator
   that helps to afford the network's OPEX, particularly for network
   maintenance.

   One clear example of the potential of the "shared infrastructure
   model" nowadays is the deployment of 3G services in rural areas in
   which there is a broadband rural community network.  Since the
   inception of femtocells, there are complete technical solutions for
   low-cost 3G coverage using the Internet as a backhaul.  If a user or



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   community of users has an IP network connected to the Internet with
   some capacity in excess, placing a femtocell in the user premises
   benefits both the user and the operator, as the user obtains better
   coverage and the operator does not have to support the cost of the
   infrastructure.  Although this paradigm was conceived for improved
   indoor coverage, the solution is feasible for 3G coverage in
   underserved rural areas with low population density (i.e. villages),
   where the number of simultaneous users and the servicing area are
   small enough to use low-cost femtocells.  Also, the amount of traffic
   produced by these cells can be easily transported by most community
   broadband rural networks.

   Some real examples can be referenced in the European Commission FP7
   TUCAN3G project, (see http://www.ict-tucan3g.eu/) which deployed
   demonstrative networks in two regions in the Amazon forest in Peru.
   In these networks [Simo_a], the operator and several rural
   communities have cooperated to provide services through rural
   networks built up with WiLD links [WiLD].  In these cases, the
   networks belong to the health public authorities and were deployed
   with funds come from international cooperation for telemedicine
   purposes.  Publications that justify the feasibility of this approach
   can also been found in that website.

2.4.  Crowdshared approaches, led by the people and third party
      stakeholders

   +-----------------------+-------------------------------------------+
   | Commercial            | community, public stakeholders, private   |
   | model/promoter        | companies                                 |
   +-----------------------+-------------------------------------------+
   | Goals and motivation  | sharing connectivity and resources        |
   +-----------------------+-------------------------------------------+
   | Administration        | distributed                               |
   +-----------------------+-------------------------------------------+
   | Technologies          | wireless                                  |
   +-----------------------+-------------------------------------------+
   | Typical scenarios     | urban and rural                           |
   +-----------------------+-------------------------------------------+

          Table 4: Crowdshared approaches characteristics summary

   These networks can be defined as a set of nodes whose owners share
   common interests (e.g. sharing connectivity; resources; peripherals)
   regardless of their physical location.  They conform to the following
   approach: the home router creates two wireless networks: one of them
   is normally used by the owner, and the other one is public.  A small
   fraction of the bandwidth is allocated to the public network, to be
   employed by any user of the service in the immediate area.  Some



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   examples are described in [PAWS] and [Sathiaseelan_c].  Other example
   is constituted by the networks created and managed by City Councils
   (e.g., [Heer]).

   In the same way, some companies [Fon] develop and sell Wi-Fi routers
   with a dual access: a Wi-Fi network for the user, and a shared one.
   A user community is created, and people can join the network in
   different ways: they can buy a router, so they share their connection
   and in turn they get access to all the routers associated to the
   community.  Some users can even get some revenue every time another
   user connects to their Wi-Fi spot.  Other users can just buy some
   passes in order to use the network.  Some telecommunications
   operators can collaborate with the community, including in their
   routers the possibility of creating these two networks.

   As in the case of main Internet Service Providers in France,
   Community Networks for urban areas are conceived as a set of APs
   sharing a common SSID among the clients favouring the nomadic access.
   For users in France, ISPs promise to cause a little impact on their
   service agreement when the shared network service is activated on
   clients' APs.  Nowadays, millions of APs are deployed around the
   country performing services of nomadism and 3G offloading, however as
   some studies demonstrate, at walking speed, there is a fair chance of
   performing file transfers [Castignani_a], [Castignani_b].  Scenarios
   studied in France and Luxembourg show that the density of APs in
   urban areas (mainly in downtown and residential areas) is quite big
   and from different ISPs.  Moreover, performed studies reveal that
   aggregating available networks can be beneficial to the client by
   using an application that manages the best connection among the
   different networks.  For improving the scanning process (or topology
   recognition), which consumes the 90% of the connection/reconnection
   process to the Community Network, the client may implement several
   techniques for selecting the best AP [Castignani_c].

   A Virtual Private Network (VPN) is created for public traffic, so it
   is completely secure and separated from the owner's connection.  The
   network capacity shared may employ a low priority, a less-than-best-
   effort or scavenger approach, so as not to harm the traffic of the
   owner of the connection [Sathiaseelan_a].

   The elements involved in a crowd-shared network are summarized below:

   - Interest: a parameter capable of providing a measure (cost) of the
   attractiveness of a node towards a specific location, in a specific
   instance in time.

   - Resources: A physical or virtual element of a global system.  For
   instance, bandwidth; energy; data; devices.



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   - The owner: End users who sign up for the service and share their
   network capacity.  As a counterpart, they can access another owners'
   home access for free.  The owner can be an end user or an entity
   (e.g. operator; virtual operator; municipality) that is to be made
   responsible for any actions concerning his/her device.

   - The user: a legal entity or an individual using or requesting a
   publicly available electronic communications' service for private or
   business purposes, without necessarily having subscribed to such
   service.

   - The Virtual Network Operator (VNO): An entity that acts in some
   aspects as a network coordinator.  It may provide services such as
   initial authentication or registering, and eventually, trust
   relationship storage.  A VNO is not an ISP given that it does not
   provide Internet access (e.g. infrastructure; naming).  A VNO is
   neither an Application Service Provider (ASP) since it does not
   provide user services.  Virtual Operators may also be stakeholders
   with socio-environmental objectives.  They can be a local government,
   grass root user communities, charities, or even content operators,
   smart grid operators, etc.  They are the ones who actually run the
   service.

   - Network operators, who have a financial incentive to lease out the
   unused capacity [Sathiaseelan_b] at lower cost to the VNOs.

   VNOs pay the sharers and the network operators, thus creating an
   incentive structure for all the actors: the end users get money for
   sharing their network, the network operators are paid by the VNOs,
   who in turn accomplish their socio-environmental role.





















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2.5.  Testbeds for research purposes

   +--------------------+----------------------------------------------+
   | Commercial         | research / academic entity                   |
   | model/promoter     |                                              |
   +--------------------+----------------------------------------------+
   | Goals and          | research                                     |
   | motivation         |                                              |
   +--------------------+----------------------------------------------+
   | Administration     | centralized initially, but it may end up in  |
   |                    | a distributed model.                         |
   +--------------------+----------------------------------------------+
   | Technologies       | wired and wireless                           |
   +--------------------+----------------------------------------------+
   | Typical scenarios  | urban and rural                              |
   +--------------------+----------------------------------------------+

                Table 5: Testbeds' characteristics summary

   In some cases, the initiative to start the network is not from the
   community, but from a research entity (e.g. a university), with the
   aim of using it for research purposes [Samanta], [Bernardi].

   The administration of these networks may start being centralized in
   most cases (administered by the academic entity) and may end up in a
   distributed model in which other local stakeholders assume part of
   the network administration [Rey].

3.  Scenarios where Alternative Networks are deployed

   Alternative Network Deployments are present in every part of the
   world.  Even in some high-income countries, these networks have been
   built as an alternative to commercial ones managed by traditional
   network operators.  This section discusses the scenarios where
   Alternative Networks have been deployed.

3.1.  Digital Divide and Alternative Networks

   Although there is no consensus on a precise definition for the term
   "developing country", it is generally used to refer to nations with a
   relatively lower standard of living.  Developing countries have also
   been defined as those which are in transition from traditional
   lifestyles towards the modern lifestyle which began in the Industrial
   Revolution.  When it comes to quantify to which extent a country is a
   developing country, the Human Development Index has been proposed by
   the United Nations in order to consider the Gross National Income
   (GNI), the life expectancy and the education level of the population
   in a single indicator.  Additionally, the Gini Index (World Bank



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   estimate) may be used to measure the inequality, as it estimates the
   dispersion of the national income (see
   http://data.worldbank.org/indicator/SI.POV.GINI).

   However, at the beginning of the 90's the debates about how to
   quantify development in a country were shaken by the appearance of
   Internet and mobile phones, which many authors consider the beginning
   of the Information Society.  With the beginning of this Digital
   Revolution, defining development based on Industrial Society concepts
   started to be challenged, and links between digital development and
   its impact on human development started to flourish.  The following
   dimensions are considered to be meaningful when measuring the digital
   development state of a country: infrastructures (availability and
   affordability); ICT (Information and Communications Technology)
   sector (human capital and technological industry); digital literacy;
   legal and regulatory framework; and content and services.  The lack
   or less extent of digital development in one or more of these
   dimensions is what has been referred as Digital Divide.  This divide
   is a new vector of inequality which - as it happened during the
   Industrial Revolution - generates a lot of progress at the expense of
   creating a lot economic poverty and exclusion.  The Digital Divide is
   considered to be a consequence of other socio-economic divides,
   while, at the same time, a reason for their rise.

   In this context, the so-called "developing countries", in order not
   to be left behind of this incipient digital revolution, motivated the
   World Summit of the Information Society which aimed at achieving "a
   people-centred, inclusive and development-oriented Information
   Society, where everyone can create, access, utilize and share
   information and knowledge, enabling individuals, communities and
   peoples to achieve their full potential in promoting their
   sustainable development and improving their quality of life" [WSIS],
   and called upon "governments, private sector, civil society and
   international organizations" to actively engage to accomplish it
   [WSIS].

   Most efforts from governments and international organizations focused
   initially on improving and extending the existing infrastructure in
   order not to leave their population behind.  As an example, one of
   the goals of the Digital Agenda for Europe [DAE] is "to increase
   regular internet usage from 60% to 75% by 2015, and from 41% to 60%
   among disadvantaged people."

   Universal Access and Service plans have taken different forms in
   different countries over the years, with very uneven success rates,
   but in most cases inadequate to the scale of the problem.  Given its
   incapacity to solve the problem, some governments included Universal
   Service and Access obligations to mobile network operators when



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   liberalizing the telecommunications market.  In combination with the
   overwhelming and unexpected uptake of mobile phones by poor people,
   this has mitigated the low access indicators existing in many
   developing countries at the beginning of the 90s [Rendon].

   Although the contribution made by mobile network operators in
   decreasing the access gap is undeniable, their model presents some
   constraints that limit the development outcomes that increased
   connectivity promises to bring.  Prices, tailored for the more
   affluent part of the population, remain unaffordable to many, who
   invest large percentages of their disposable income in
   communications.  Additionally, the cost of prepaid packages, the only
   option available for the informal economies existing throughout
   developing countries, is high compared with the rate longer-term
   subscribers pay.

   The consolidation of many Alternative Networks (e.g.  Community
   Networks) in high income countries sets a precedent for civil society
   members from the so-called developing countries to become more active
   in the search for alternatives to provide themselves with affordable
   access.  Furthermore, Alternative Networks could contribute to other
   dimensions of the digital development like increased human capital
   and the creation of contents and services targeting the locality of
   each network.

3.2.  Urban vs. rural areas

   The Digital Divide presented in the previous section is not only
   present between countries, but within them too.  This is specially
   the case for rural inhabitants, which represents approximately 55% of
   the world's population, from which 78% inhabit in developing
   countries.  Although it is impossible to generalize among them, there
   exist some common features that have determined the availability of
   ICT infrastructure in these regions.  The disposable income of their
   dwellers is lower than those inhabiting urban areas, with many
   surviving on a subsistence economy.  Many of them are located in
   geographies difficult to access and exposed to extreme weather
   conditions.  This has resulted in the almost complete lack of
   electrical infrastructure.  This context, together with their low
   population density, discourages telecommunications operators to
   provide similar services to those provided to urban dwellers, since
   they do not deem them profitable.

   The cost of the wireless infrastructure required to set up a network,
   including powering it (e.g. via solar energy), is within the range of
   availability if not of individuals at least of entire communities.
   The social capital existing in these areas can allow for Alternative
   Network set-ups where a reduced number of nodes may cover communities



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   whose dwellers share the cost of the infrastructure and the gateway
   and access it via inexpensive wireless devices.  Some examples are
   presented in [Pietrosemoli] and [Bernardi].

   In this case, the lack of awareness and confidence of rural
   communities to embark themselves in such tasks can become major
   barriers to their deployment.  Scarce technical skills in these
   regions have also been pointed as a challenge for their success, but
   the proliferation of urban Community Networks, where scarcity of
   spectrum, scale, and heterogeneity of devices pose tremendous
   challenges to their stability and the services they aim to provide,
   has fuelled the creation of robust low-cost low-consumption low-
   complexity off-the-shelf wireless devices which make much easier the
   deployment and maintenance of these alternative infrastructures in
   rural areas.

3.3.  Gap between demanded and provided communications services

   Beyond the Digital Divide, either international or domestic, there
   are many situations in which the market fails to provide the
   information and communications services demanded by the population.
   When this happens permanently in an area, citizens may be compelled
   to take a more active part in the design and implementation of ICT
   solutions, hence promoting Alternative Networks.

3.4.  Topology patterns followed by Alternative Networks

   Alternative Networks, considered self-managed and self-sustained,
   follow different topology patterns [Vega].  Generally, these networks
   grow spontaneously and organically, that is, the network grows
   without specific planning and deployment strategy and the routing
   core of the network fits fairly well a power law distribution.
   Moreover, the network is composed of a high number of heterogeneous
   devices with the common objective of freely connecting and increasing
   the network coverage.  Although these characteristics increase the
   entropy (e.g., by increasing the number of routing protocols), they
   have resulted in an inexpensive solution to effectively increase the
   network size.  One example corresponds to Guifi.net [Vega] with an
   exponential grow rate in the number of operating nodes during the
   last decade.

   Regularly rural areas in these networks are connected through long-
   distance links (the so-called community mesh approach) which in turn
   convey the Internet connection to relevant organisations or
   institutions.  In contrast, in urban areas, users tend to share and
   require mobile access.  Since these areas are also likely to be
   covered by commercial ISPs, the provision of wireless access by
   Virtual Operators like [Fon] may constitute a way to extend the user



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   capacity (or gain connection) to the network.  Other proposals like
   Virtual Public Networks [Sathiaseelan_a] can also extend the service.

4.  Technologies employed

4.1.  Wired

   In many (developed or developing) countries it may happen that
   national service providers may decline to provide connectivity to
   tiny and isolated villages.  So in some cases the villagers have
   created their own optical fiber networks.  It is the case of
   Lowenstedt in Germany [Lowenstedt], or some parts of Guifi.net
   [Cerda-Alabern].

4.2.  Wireless

   The vast majority of the Alternative Network Deployments are based on
   different wireless technologies [WNDW].  Below we summarize topics to
   be considered in such deployments.  Different considerations about
   the available options are presented, including physical and Media
   Access Control (MAC) layers.  In addition, the trends (and some
   recommendations) when using these features in Alternative Networks
   are summarized.

4.2.1.  Antennas

   Three kinds of antennas are suitable to be used in these networks:
   omnidirectional, low-gain directional and high-gain directional
   antennas.

   For local access, omnidirectional antennas are the most useful, since
   they provide the same coverage in all directions of the plane in
   which they are located.  Above and below this plane, the received
   signal will diminish, so the maximum benefits are obtained when the
   client is at approximately the same height as the Access Point.

   For indoor clients, omnidirectional antennas are generally fine,
   because the numerous reflections normally found in indoor
   environments negate the advantage of using directional antennas.

   For outdoor clients, directional antennas can be quite useful to
   extend coverage to an Access Point fitted with an omnidirectional
   one.

   When building point-to-point links, the highest gain antennas are the
   best choice, since their narrow beamwidth mitigates interference from
   other users and can provide the longest links [Flickenger],
   [Zennaro].



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   Despite the fact that the free space loss is directly proportional to
   the square of the frequency, it is normally advisable to use higher
   frequencies for point-to-point links when there is a clear line of
   sight, because it is normally easier to get higher gain antennas, the
   protection against interferences is better and the spectrum
   saturation is lower.  Deploying high gain antennas at both ends will
   more than compensate for the additional free space loss.

   On the contrary, lower frequencies offer advantages when the line of
   sight may be blocked because they can leverage diffraction to reach
   the intended receiver.

   In the case of mesh networking, where the antenna should connect to
   several other nodes, it is better to use omnidirectional antennas.

   The same type of polarization must be used at both ends of any radio
   link.  For point-to-point links, parabolic antennas exist that may
   transmit/receive two different signals simultaneously at the same
   frequency but with orthogonal polarizations, thus permitting to
   increase the achievable throughput significantly and to improve the
   protection to multipath and to other transmission impairments.

4.2.2.  Physical link length

4.2.2.1.  Line-of-Sight

   For short distance transmission, there is no strict requirement of
   line of sight between the transmitter and the receiver, and multipath
   can guarantee communication despite the existence of obstacles in the
   direct path.

   For longer distances, the first requirement is the existence of an
   unobstructed line of sight between the transmitter and the receiver.
   For very long paths, the earth curvature is an obstacle that must be
   cleared, but the trajectory of the radio beam is not strictly a
   straight line due to the bending of the rays as a consequence of non-
   uniformities of the atmosphere.  Most of the time this bending will
   mean that the radio horizon extends further than the optical horizon.

4.2.2.2.  Transmitted and Received Power

   Once a clear radio-electric line of sight is obtained, it is required
   that the received power is significantly above the sensitivity of the
   receiver, by what is known as the "link margin".  The greater the
   link margin, the more reliable the link.  For mission critical
   applications 20 dB margin is suggested, but for non critical ones 10
   dB might suffice.




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   The sensitivity of the receiver decreases with the transmission
   speed, so more power is needed at greater transmission speeds.

   Different options can be considered in order to achieve a given link
   margin (also called "fade margin"):

   a) To increase the output power.The maximum transmitted power is
   specified by each country's regulation, and for unlicensed
   frequencies is much lower than for licensed frequencies.

   b) To increase the antenna gain.  There is no limit in the gain of
   the receiving antenna, but high gain antennas are bulkier, present
   more wind resistance and require sturdy mounts to comply with tighter
   alignment requirements.  The transmitter antenna gain is also
   regulated and can be different for point-to-point as for point-to-
   multipoint links.

   c) To reduce the propagation loss, by using a more favorable
   frequency or a shorter path.

   d) To use a more sensitive receiver.  Receiver sensitivity can be
   improved by using better circuits, but it is ultimately limited by
   the thermal noise, which is proportional to temperature and
   bandwidth.  One can increase the sensitivity by using a smaller
   receiving bandwidth, or by settling to lower throughput even in the
   same receiver bandwidth.

4.2.3.  Media Access Control (MAC) Protocols for Wireless Links

   Different protocols for Media Access Control, which also include
   physical layer (PHY) recommendations, are widely used in Alternative
   Network Deployments.  Wireless standards ensure interoperability and
   usability to those who design, deploy and manage wireless networks.

   The standards used in the vast majority of Alternative Networks come
   from the IEEE Standard Association's IEEE 802 Working Group.
   Standards developed by other international entities can also be used,
   as e.g. the European Telecommunications Standards Institute (ETSI).

4.2.3.1.  802.11 (Wi-Fi)

   The standard we are most interested in is 802.11 a/b/g/n/ac, as it
   defines the protocol for Wireless LAN.  It is also known as "Wi-Fi".
   The original release (a/b) was issued in 1999 and allowed for rates
   up to 54 Mbit/s.  The latest release (802.11ac) issued in 2011
   reaches up to 866.7 Mbit/s.  In 2012, the IEEE issued the 802.11-2012
   Standard that consolidates all the previous amendments.  The document
   is freely downloadable from IEEE Standards [IEEE].



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4.2.3.1.1.  Deployment planning for 802.11 wireless networks

   To provide physical connectivity, wireless network devices must
   operate in the same part of the radio spectrum.  This means that
   802.11a radios will talk to 802.11a radios at around 5 GHz, and
   802.11b/g radios will talk to other 802.11b/g radios at around 2.4
   GHz.  But an 802.11a device cannot interoperate with an 802.11b/g
   device, since they use completely different parts of the
   electromagnetic spectrum.  More specifically, wireless interfaces
   must agree on a common channel.  If one 802.11b radio card is set to
   channel 2 while another is set to channel 11, then the radios cannot
   communicate with each other.

   Each 802.11 device can operate in one of four possible modes:

   1.  Master mode (also called AP or infrastructure mode) is used to
   create a service that looks like a traditional Access Point.
   Wireless interfaces in master mode can only communicate with
   interfaces that are associated with them in managed mode.

   2.  Managed mode is sometimes also referred to as client mode.
   Wireless interfaces in managed mode will join a network created by a
   master, and will automatically change their channel to match it.
   Managed mode interfaces do not communicate with each other directly,
   and only communicate with an associated master.

   3.  Ad-hoc mode creates a multipoint-to-multipoint network where
   there is no single master node or AP.  In ad-hoc mode, each wireless
   interface communicates directly with its neighbors.  Ad-hoc mode is
   often also called Mesh Networking.

   4.  Monitor mode is used by some tools (such as Kismet) to passively
   listen to all radio traffic on a given channel.

   When implementing a point-to-point or point-to-multipoint link, one
   radio will typically operate in master mode, while the other(s)
   operate in managed mode.  Ad-hoc is more flexible but has a number of
   performance issues as compared to using the master / managed modes.

4.2.3.1.2.  Long Distances in 802.11

   The MAC protocol in 802.11 is called CSMA/CA (Carrier Sense Multiple
   Access with Collision Avoidance) and was designed for short
   distances; the transmitter expects the reception of an acknowledgment
   for each transmitted unicast packet; if a certain waiting time is
   exceeded, the packet is retransmitted.  This behavior makes necessary
   the adaptation of several MAC parameters when 802.11 is used in long
   links [Simo_b].  Even with this adaptation, the distance has a



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   significant negative impact on the performance.  For this reason,
   many vendors implement alternative medium access techniques that are
   offered alongside the standard CSMA/CA in their outdoor 802.11
   products.  These alternative proprietary MAC protocols usually employ
   some type of TDMA (Time Division Multiple Access).  Low cost
   equipment using these techniques can offer high throughput at
   distances above 100 kilometers.

4.2.3.2.  GSM

   GSM (Global System for Mobile Communications), from ETSI, has also
   been used in Alternative Networks as Layer 2 option, as explained in
   [Mexican].

4.2.3.3.  Dynamic Spectrum

   Some Alternative Networks make use of TV White Spaces - a set of UHF
   and VHF television frequencies that can be utilized by secondary
   users in locations where it is unused by licensed primary users such
   as television broadcasters.  Equipment that makes use of TV White
   Spaces is required to detect the presence of existing unused TV
   channels by means of a spectrum database and/or spectrum sensing in
   order to ensure that no harmful interference is caused to primary
   users.  In order to smartly allocate interference-free channels to
   the devices, cognitive radios are used which are able to modify their
   frequency, power and modulation techniques to meet the strict
   operating conditions required for secondary users.

   The use of the term "White Spaces" is often used to describe "TV
   White Spaces" as the VHF and UHF television frequencies were the
   first to be exploited on a secondary use basis.  There are two
   dominant standards for TV white space communication: (i) the 802.11af
   standard [IEEE.802-11AF.2013] - an adaptation of the 802.11 standard
   for TV white space bands and (ii) the IEEE 802.22 standard
   [IEEE.802-22.2011] for long-range rural communication.

4.2.3.3.1.  802.11af

   802.11af [IEEE.802-11AF.2013] is a modified version of the 802.11
   standard operating in TV White Space bands using Cognitive Radios to
   avoid interference with primary users.  The standard is often
   referred to as White-Fi or "Super Wi-Fi" and was approved in February
   2014. 802.11af contains much of the advances of all the 802.11
   standards including recent advances in 802.11ac such as up to four
   bonded channels, four spatial streams and very high rate 256-QAM
   modulation but with improved in-building penetration and outdoor
   coverage.  The maximum data rate achievable is 426.7 Mbps for
   countries with 6/7 MHz channels and 568.9 Mbps for countries with 8



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   MHz channels.  Coverage is typically limited to 1km although longer
   range at lower throughput and using high gain antennas will be
   possible.

   Devices are designated as enabling stations (Access Points) or
   dependent stations (clients).  Enabling stations are authorized to
   control the operation of a dependent station and securely access a
   geolocation database.  Once the enabling station has received a list
   of available white space channels it can announce a chosen channel to
   the dependent stations for them to communicate with the enabling
   station. 802.11af also makes use of a registered location server - a
   local database that organizes the geographic location and operating
   parameters of all enabling stations.

4.2.3.3.2.  802.22

   802.22 [IEEE.802-22.2011] is a standard developed specifically for
   long range rural communications in TV white space frequencies and
   first approved in July 2011.  The standard is similar to the 802.16
   (WiMax) [IEEE.802-16.2008] standard with an added cognitive radio
   ability.  The maximum throughput of 802.22 is 22.6 Mbps for a single
   8 MHz channel using 64-QAM modulation.  The achievable range using
   the default MAC scheme is 30 km, however 100 km is possible with
   special scheduling techniques.  The MAC of 802.22 is specifically
   customized for long distances - for example, slots in a frame
   destined for more distant Consumer Premises Equipment (CPEs) are sent
   before slots destined for nearby CPEs.

   Base stations are required to have a Global Positioning System (GPS)
   and a connection to the Internet in order to query a geolocation
   spectrum database.  Once the base station receives the allowed TV
   channels, it communicates a preferred operating white space TV
   channel with the CPE devices.  The standard also includes a co-
   existence mechanism that uses beacons to make other 802.22 base
   stations aware of the presence of a base station that is not part of
   the same network.

5.  Upper layers

5.1.  Layer 3

5.1.1.  IP addressing

   Most known Alternative Networks started in or around the year 2000.
   IPv6 was fully specified by then, but almost all Alternative Networks
   still use IPv4.  A survey [Avonts] indicated that IPv6 rollout
   presents a challenge to Community Networks.




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   Most Community Networks use private IPv4 address ranges, as defined
   by [RFC1918].  The motivation for this was the lower cost and the
   simplified IP allocation because of the large available address
   ranges.

5.1.2.  Routing protocols

   As stated in previous sections, Alternative Networks are composed of
   possibly different layer 2 devices, resulting in a mesh of nodes.
   Connection between different nodes is not guaranteed and the link
   stability can vary strongly over time.  To tackle this, some
   Alternative Networks use mesh network routing protocols while other
   networks use more traditional routing protocols.  Some networks
   operate multiple routing protocols in parallel.  For example, they
   use a mesh protocol inside different islands and use traditional
   routing protocols to connect these islands.

5.1.2.1.  Traditional routing protocols

   The Border Gateway Protocol (BGP), as defined by [RFC4271] is used by
   a number of Community Networks, because of its well-studied behavior
   and scalability.

   For similar reasons, smaller networks opt to run the Open Shortest
   Path First (OSPF) protocol, as defined by [RFC2328].

5.1.2.2.  Mesh routing protocols

   A large number of Alternative Networks use the Optimized Link State
   Routing Protocol (OLSR) routing protocol as defined in [RFC3626].
   The pro-active link state routing protocol is a good match with
   Alternative Networks because it has good performance in mesh networks
   where nodes have multiple interfaces.

   The Better Approach To Mobile Adhoc Networking (BATMAN) [Abolhasan]
   protocol was developed by members of the Freifunk community.  The
   protocol handles all routing at layer 2, creating one bridged
   network.

   Parallel to BGP, some networks also run the BatMan-eXperimental
   (BMX6) protocol [Neumann].  This is an advanced version of the BATMAN
   protocol which is based on IPv6 and tries to exploit the social
   structure of Alternative Networks.








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5.2.  Transport layer

5.2.1.  Traffic Management when sharing network resources

   When network resources are shared, a special care has to be put on
   the management of the traffic at upper layers.  From a crowdshared
   perspective, and considering just regular TCP connections during the
   critical sharing time, the Access Point offering the service is
   likely to be the bottleneck of the connection.  This is the main
   concern of sharers, having several implications.  There should be an
   adequate Active Queue Management (AQM) mechanism that implements a
   Lower-than-best-effort (LBE) [RFC6297] policy for the user and
   protects the sharer.  Achieving LBE behavior requires the appropriate
   tuning of the well known mechanisms such as Explicit Congestion
   Notification (ECN) [RFC3168], or Random Early Detection (RED)
   [RFC2309], or other more recent AQM mechanisms such as Controlled
   Delay (CoDel) and [I-D.ietf-aqm-codel] PIE (Proportional Integral
   controller Enhanced) [I-D.ietf-aqm-pie] that aid on keeping low
   latency.

   However, other bottlenecks besides client's access bottleneck may not
   be controlled by the previously mentioned protocols.  Therefore,
   recently proposed transport protocols like LEDBAT [Ros], [Komnios]
   with the purpose of transporting scavenger traffic may be a solution.
   LEDBAT requires the cooperation of both the client and the server to
   achieve certain target delay, therefore controlling the impact of the
   user along all the path.

   There are applications that manage aspects of the network from the
   sharer side and from the client side.  From sharer's side, there are
   applications to centralize the management of the APs conforming the
   network that have been recently proposed by means of SDN
   [Sathiaseelan_a], [Suresh].  There are also other proposals such as
   Wi2Me [Lampropulos] that manage the connection to several Community
   Networks from the client's side.  These applications have shown to
   improve the client performance compared to a single-Community Network
   client.

5.2.2.  Multi-hop issues

   On the other hand, transport protocols inside a multiple hop wireless
   mesh network are likely to suffer performance degradation for
   multiple reasons, e.g., hidden terminal problem, unnecessary delays
   on the TCP ACK clocking that decrease the throughout or route
   changing [Hanbali].  There are some options for network
   configuration.  The implementation of an easy-to-adopt solution for
   TCP over mesh networks may be implemented from two different
   perspectives.  One way is to use a TCP-proxy to transparently deal



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   with the different impairments ([RFC3135]).  Another way is to adopt
   end-to-end solutions for monitoring the connection delay so that the
   receiver adapts the TCP reception window (rwnd) [Castignani_c].
   Similarly, the ACK Congestion Control (ACKCC) mechanism [RFC5690]
   could deal with TCP-ACK clocking impairments due to inappropriate
   delay on ACK packets.  ACKCC compensates in an end-to-end fashion the
   throughput degradation due to the effect of media contention as well
   as the unfairness experienced by multiple uplink TCP flows in a
   congested Wi-Fi access.

5.3.  Services provided

   This section provides an overview of the services between hosts
   inside the network.  They can be divided into Intranet services,
   connecting hosts between them, and Internet services, connecting to
   nodes outside the network.

5.3.1.  Intranet services

   Intranet services can include, but are not limited to:

   - VoIP (e.g. with SIP)

   - Remote desktop (e.g. using my home computer and my Internet
   connection when I am on holidays in a village).

   - FTP file sharing (e.g. distribution of Linux software).

   - P2P file sharing.

   - Public video cameras.

   - DNS.

   - Online games servers.

   - Jabber instant messaging.

   - IRC chat.

   - Weather stations.

   - NTP.

   - Network monitoring.

   - Videoconferencing / streaming.




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   - Radio streaming.

5.3.2.  Access to the Internet

5.3.2.1.  Web browsing proxies

   A number of federated proxies may provide web browsing service for
   the users.  Other services (file sharing, skype, etc.) are not
   usually allowed in many Alternative Networks due to bandwidth
   limitations.

5.3.2.2.  Use of VPNs

   Some "micro-ISPs" may use the network as a backhaul for providing
   Internet access, setting up VPNs from the client to a machine with
   Internet access.

6.  Acknowledgements

   This work has been partially funded by the CONFINE European
   Commission Project (FP7 - 288535).  Arjuna Sathiaseelan and Andres
   Arcia Moret were funded by the EU H2020 RIFE project (Grant Agreement
   no: 644663).  Jose Saldana was funded by the EU H2020 Wi-5 project
   (Grant Agreement no: 644262).

   The editor and the authors of this document wish to thank the
   following individuals who have participated in the drafting, review,
   and discussion of this memo:

   Paul M.  Aoki, Roger Baig, Jaume Barcelo, Steven G.  Huter, Rohan
   Mahy, Rute Sofia, Dirk Trossen.

   A special thanks to the GAIA Working Group chairs Mat Ford and Arjuna
   Sathiaseelan for their support and guidance.

7.  Contributing Authors

   Leandro Navarro
   U. Politecnica Catalunya
   Jordi Girona, 1-3, D6
   Barcelona  08034
   Spain

   Phone: +34 934016807
   Email: leandro@ac.upc.edu






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   Carlos Rey-Moreno
   University of the Western Cape
   Robert Sobukwe road
   Bellville  7535
   South Africa

   Phone: 0027219592562
   Email: crey-moreno@uwc.ac.za

   Ioannis Komnios
   Democritus University of Thrace
   Department of Electrical and Computer Engineering
   Kimmeria University Campus
   Xanthi 67100
   Greece

   Phone: +306945406585
   Email: ikomnios@ee.duth.gr

   Steve Song
   Village Telco Limited


   Halifax
   Canada

   Phone:
   Email: stevesong@nsrc.org

   David Lloyd Johnson
   Meraka, CSIR
   15 Lower Hope St
   Rosebank 7700
   South Africa

   Phone: +27 (0)21 658 2740
   Email: djohnson@csir.co.za

   Javier Simo-Reigadas
   Escuela Tecnica Superior de Ingenieria de Telecomunicacion
   Campus de Fuenlabrada
   Universidad Rey Juan Carlos
   Madrid
   Spain

   Phone: 91 488 8428 / 7500
   Email: javier.simo@urjc.es




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8.  IANA Considerations

   This memo includes no request to IANA.

9.  Security Considerations

   No security issues have been identified for this document.

10.  References

10.1.  Normative References

   [IEEE]     Institute of Electrical and Electronics Engineers, IEEE,
              "IEEE Standards association", 2012.

   [IEEE.802-11AF.2013]
              "Information technology - Telecommunications and
              information exchange between systems - Local and
              metropolitan area networks - Specific requirements - Part
              11: Wireless LAN Medium Access Control (MAC) and Physical
              Layer (PHY) specifications - Amendment 5: Television White
              Spaces (TVWS) Operation", IEEE Standard 802.11af, Oct
              2009, <http://standards.ieee.org/getieee802/
              download/802.11af-2013.pdf>.

   [IEEE.802-16.2008]
              "Information technology - Telecommunications and
              information exchange between systems - Broadband wireless
              metropolitan area networks (MANs) - IEEE Standard for Air
              Interface for Broadband Wireless Access Systems", IEEE
              Standard 802.16, Jun 2008,
              <http://standards.ieee.org/getieee802/
              download/802.16-2012.pdf>.

   [IEEE.802-22.2011]
              "Information technology - Telecommunications and
              information exchange between systems - Local and
              metropolitan area networks - Specific requirements - Part
              22: Cognitive Wireless RAN Medium Access Control (MAC) and
              Physical Layer (PHY) specifications: Policies and
              procedures for operation in the TV Bands", IEEE Standard
              802.22, Jul 2011, <http://standards.ieee.org/getieee802/
              download/802.11af-2013.pdf>.

   [RFC1918]  Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
              E. Lear, "Address Allocation for Private Internets", BCP
              5, RFC 1918, February 1996.




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   [RFC2309]  Braden, B., Clark, D., Crowcroft, J., Davie, B., Deering,
              S., Estrin, D., Floyd, S., Jacobson, V., Minshall, G.,
              Partridge, C., Peterson, L., Ramakrishnan, K., Shenker,
              S., Wroclawski, J., and L. Zhang, "Recommendations on
              Queue Management and Congestion Avoidance in the
              Internet", RFC 2309, April 1998.

   [RFC2328]  Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.

   [RFC3135]  Border, J., Kojo, M., Griner, J., Montenegro, G., and Z.
              Shelby, "Performance Enhancing Proxies Intended to
              Mitigate Link-Related Degradations", RFC 3135, June 2001.

   [RFC3168]  Ramakrishnan, K., Floyd, S., and D. Black, "The Addition
              of Explicit Congestion Notification (ECN) to IP", RFC
              3168, September 2001.

   [RFC3626]  Clausen, T. and P. Jacquet, "Optimized Link State Routing
              Protocol (OLSR)", RFC 3626, October 2003.

   [RFC4271]  Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
              Protocol 4 (BGP-4)", RFC 4271, January 2006.

   [RFC5690]  Floyd, S., Arcia, A., Ros, D., and J. Iyengar, "Adding
              Acknowledgement Congestion Control to TCP", RFC 5690,
              February 2010.

   [RFC6297]  Welzl, M. and D. Ros, "A Survey of Lower-than-Best-Effort
              Transport Protocols", RFC 6297, June 2011.

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              based Examination of Community Networks", Proceedings
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              i Balaguer, I., Tatum, B., Matson, M., Blondia, C., Barz,
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              Papathanasiou, S., and P. Escrich, "A case for research
              with and on community networks", ACM SIGCOMM Computer
              Communication Review vol. 43, no. 3, pp. 68-73, 2013.

   [Castignani_a]
              Castignani, G., Loiseau, L., and N. Montavont, "An
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              Foundation", The Free Network Foundation web page,
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              https://corp.fon.com/en , 2014.

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              over Ad Hoc Networks", IEEE Commun. Surv. Tutorials, vol.
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              K. Wehrle, "Collaborative municipal Wi-Fi networks-
              challenges and opportunities", Pervasive Computing and
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              International Conference on (pp. 588-593). IEEE. , 2010.

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              Nichols, K., Jacobson, V., McGregor, A., and J. Jana,
              "Controlled Delay Active Queue Management", draft-ietf-
              aqm-codel-01 (work in progress), April 2015.

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              Pan, R., Natarajan, P., Baker, F., and G. White, "PIE: A
              Lightweight Control Scheme To Address the Bufferbloat
              Problem", draft-ietf-aqm-pie-01 (work in progress), March
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              performance in subpacket regimes", IEEE/IFIP WONS,
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              Lampropulos, A., Castignani, G., Blanc, A., and N.
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              2012, pp. 108-113 , 2012.







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              Huggler, J., "Lowenstedt Villagers Built Own Fiber Optic
              Network", The Telegraph, 03 Jun 2014, available at
              http://www.telegraph.co.uk/news/worldnews/europe/
              germany/10871150/
              German-villagers-set-up-their-own-broadband-network.html ,
              2014.

   [Mexican]  Varma, S., "Lowenstedt Villagers Built Own Fiber Optic
              Network", The Times of India, 27 Aug 2013, available at
              http://timesofindia.indiatimes.com/world/rest-of-world/
              Ignored-by-big-companies-Mexican-village-creates-its-own-
              mobile-service/articleshow/22094736.cms , 2013.

   [Neumann]  Neumann, A., Lopez, E., and L. Navarro, "An evaluation of
              bmx6 for community wireless networks", In Wireless and
              Mobile Computing, Networking and Communications (WiMob),
              2012 IEEE 8th International Conference on (pp. 651-658).
              IEEE. , 2012.

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              Greiffenhagen, C., Mortier, R., Fairhurst, G., and D.
              McAuley, "Public Access WiFi Service (PAWS)", Digital
              Economy All Hands Meeting, Aberdeen , Oct 2012.

   [Pietrosemoli]
              Pietrosemoli, E., Zennaro, M., and C. Fonda, "Low cost
              carrier independent telecommunications infrastructure", In
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   [Rendon]   Rendon, A., Ludena, P., and A. Martinez Fernandez,
              "Tecnologias de la Informacion y las Comunicaciones para
              zonas rurales Aplicacion a la atencion de salud en paises
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              y Tecnologia para el Desarrollo , 2011.

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              Quispe-Taca, R., Linan-Benitez, L., and J. Simo-Reigadas,
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              in the Amazonian jungle of Peru.", Proceedings of the 3rd
              Extreme Conference on Communication: The Amazon
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              "Metropolitan Wi-Fi Research Network at the Los Angeles
              State Historic Park", The Journal of Community
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              C., Radenkovic, M., Crowcroft, J., and D. McAuley, "A
              Feasibility Study of an In-the-Wild Experimental Public
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Authors' Addresses

   Jose Saldana (editor)
   University of Zaragoza
   Dpt. IEC Ada Byron Building
   Zaragoza  50018
   Spain

   Phone: +34 976 762 698
   Email: jsaldana@unizar.es


   Andres Arcia-Moret
   University of Cambridge
   15 JJ Thomson Avenue
   Cambridge  FE04
   United Kingdom

   Phone: +44 (0) 1223 763610
   Email: andres.arcia@cl.cam.ac.uk









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   Bart Braem
   iMinds
   Gaston Crommenlaan 8 (bus 102)
   Gent  9050
   Belgium

   Phone: +32 3 265 38 64
   Email: bart.braem@iminds.be


   Ermanno Pietrosemoli
   ICTP
   Via Beirut 7
   Trieste  34151
   Italy

   Phone: +39 040 2240 471
   Email: ermanno@ictp.it


   Arjuna Sathiaseelan
   University of Cambridge
   15 JJ Thomson Avenue
   Cambridge  CB30FD
   United Kingdom

   Phone: +44 (0)1223 763781
   Email: arjuna.sathiaseelan@cl.cam.ac.uk


   Marco Zennaro
   Abdus Salam ICTP
   Strada Costiera 11
   Trieste  34100
   Italy

   Phone: +39 040 2240 406
   Email: mzennaro@ictp.it













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