#+title: Community-Lab: A Community Networking Testbed for the Future Internet
* Introduction
** Community networks
- Origins: In spite of the importance of the Internet, companies and
governments left behind people and regions of little economic interest for
them. Thus some groups started coordinating the deployment of their own
networks for self-provision.
- Characteristics: Open participation, open and transparent management,
distributed ownership, works and grows according to users' interests.
- Prospective: Strategic importance for the expansion of broadband access
throughout Europe (as stated in the European Digital Agenda).
- A challenge: How to support the growth and sustainability of community
networks by providing the means to conduct experimentally driven research.
** The CONFINE project (Community Networks Testbed for the Future Internet)
- Takes on the previous challenge.
- Project supported by the European Community Framework Programme 7 within the
Future Internet Research and Experimentation Initiative (FIRE).
- Partners (list with logos): Fundació guifi.net, Funkfeuer, Athens Wireless
Metropolitan Network (community networks); Universitat Politècnica de
Catalunya, Fraunhofer Institute for Communication, Information Processing
and Ergonomics, Interdisciplinary Institute for Broadband Technology
(research centres); the OPLAN Foundation, Pangea (NGOs).
- Objectives: Provide a testbed and associated tools and knowledge for
researchers to experiment on real community networks.
** Testbeds
- Environments built with real hardware for realistic experimental research on
network technologies (instead of simulations).
- Wireless: Berlin RoofNet, MIT Roofnet (outdoor); IBBT's w-iLab.t, CERTH's
NITOS, WINLAB's ORBIT (indoor). Limited local scale, controlled
environment, no resource sharing between experiments.
- Internet: PlanetLab, planet-scale testbed with resource sharing on nodes.
Main inspiration for Community-Lab.
** Community-Lab: a testbed for community networks
- The testbed developed by CONFINE.
- Integrates and extends three Community Networks: guifi.net, FunkFeuer, AWMN.
# Node maps here for CNs with captures from node DBs.
- Also nodes in participating research centres.
- Linked together over the FEDERICA backbone.
- All its software and documentation is released under Free licenses, anyone
can setup a CONFINE testbed like Community-Lab.
* Challenges and requirements
** Simple management vs. Distributed node ownership
- In contrast with e.g. indoors testbeds that belong wholly to the same
entity.
** Features vs. Lightweight, low cost (free & open)
- Devices ranging from PCs to embedded boards.
- Need light system able to run on very different devices.
** Familiarity & flexibility vs. System stability
- Familiar Linux env with root access to researchers.
- Keep env isolation (nodes are shared by experiments).
- Keep node stability (to avoid in-place maintenance, some difficult to reach
node locations).
# Frozen tower.
** Flexibility vs. Network stability
- Network experiments running on nodes in a production network.
- Allow interaction with CN at the lowest level possible but not disrupting or
overusing it.
** Traffic collection vs. Privacy of CN users
- Experiments performing traffic collection and characterization.
- Avoid researchers spying on users' data.
** Link instability vs. Management robustness
- Deal with frequent network outages in the CN.
** Reachability vs. IP address provisioning
- Testbed spanning different CNs.
- IPv4 scarcity and incompatibility between CNs, lack of IPv6 support.
** Heterogeneity vs. Compatibility
- Lots of different devices (disparate connectivity and software openness).
- Lots of different link technologies (wireless, wired, fiber).
* Community-Lab testbed architecture
** Overall architecture
This architecture applies to all testbeds using the CONFINE software.
# Move over overlay diagram less overlay connections plus overlay network.
- A testbed consists of a set of nodes managed by the same server.
- Server managed by testbed admins.
- Network and node managed by node admins (usually owners and CN members).
- Node admins must adhere to testbed conditions.
- This decouples testbed management from infrastructure ownership and mgmt.
- Testbed management traffic uses a tinc mesh VPN:
- Avoids problems with firewalls and private networks in nodes.
- Uses IPv6 to avoid address scarcity and incompatibility between CNs.
- Short-lived mgmt connections make components mostly autonomous and
tolerant to link instability.
- A testbed can span multiple CNs thanks to gateways.
- Bridging the mgmt net over external means (e.g. FEDERICA, the Internet).
- Gateways can route the management network to the Internet.
- A researcher runs the experiments of a slice in slivers each running in a
different node…
** Nodes, slices and slivers
- …a model inspired in PlanetLab.
- The slice (a management concept) groups a set of related slivers.
- A sliver holds the resources (CPU, memory, disk, bandwidth, interfaces…)
allocated for a slice in a given node.
# Diagram: Slices and slivers, two or three nodes with a few slivers on them,
# each with a color identifying it with a slice.)
** Node architecture
# Node simplified diagram, hover to interesting parts.
- The community device
- Completely normal CN device, so existing ones can be used.
- Routes traffic between the CN and devices in the node's wired local
network (which runs no routing protocol).
- The research device
- Usually more powerful than CD, since experiments run here.
- Separating CD/RD makes integration with any CN simple and safe:
- Little CONFINE-specific tampering with CN infrastructure.
- Little CN-specific configuration for RDs.
- Misbehaving experiments can't crash CN infrastructure.
- Runs OpenWrt firmware customized by CONFINE.
- Slivers are implemented as Linux containers.
- Lightweight virtualization supported mainstream.
- Provides a familiar and flexible env for researchers.
- Direct interfaces allow experiments to bypass the CD when interacting with
the CN.
- Control software
- Uses LXC tools on containers to enforce resource limitation, resource
isolation and node stability.
- Uses traffic control, filtering and anonymization to ensure network
stability, isolation and privacy.
- The recovery device can force a hardware reboot of the RD from several
triggers and help with upgrade and recovery.
** Node and sliver connectivity
# Node simplified diagram, hover to interesting parts.
Slivers can be configured with different types of network interfaces depending
on what connectivity researchers need for experiments:
- Home computer behind a NAT router: a private interface with traffic
forwarded using NAT to the CN and filtered to ensure network stability.
- Publicly open service: a public interface (with a public CN address) with
traffic routed directly to the CN and filtered to ensure network stability.
- Traffic capture: a passive interface using a direct interface for capture.
Incoming traffic is filtered and anonymized to ensure network privacy.
- Routing: an isolated interface using a VLAN on top of a direct interface.
It only can reach other slivers of the same slice with isolated interfaces
on the same link. All traffic is allowed.
- Low-level testing: the sliver is given raw access to the interface. For
privacy, isolation and stability reasons this should only be allowed in
exceptional occasions.
* How the testbed works
# Event diagram, hover over components explained.
An example experiment: two slivers, one of them (source sliver) pings the
other one (target sliver).
1. The researcher first contacts the server and creates a slice description
which specifies a template for slivers (e.g. Debian Squeeze i386).
Experiment data is attached including a program to setup the experiment and
another one to run it.
2. The server updates the registry which holds all definitions of testbed,
nodes, users, slices, slivers, etc.
3. The researcher chooses a couple of nodes and creates sliver descriptions
for them belonging to the previous slice. Both sliver descriptions include
a public interface to the CN and user-defined properties for telling apart
the source sliver from the target one. Sliver descriptions go to the
registry.
4. Each of the previous nodes gets a sliver description for it. If enough
resources are available, a container is created by applying the desired
configuration over the selected template.
5. Once the researcher knows that slivers have been instantiated, the server
can be commanded to activate the slice. The server updates the registry.
6. When nodes get instructions to activate slivers they start the containers.
7. Containers run the experiment setup program and the run program. The
programs query sliver properties to decide their behaviour.
8. Researchers interact straight with containers if needed (e.g. via SSH) and
collect results from them.
9. When finished, the researcher tells the server to deactivate and
deinstantiate the slice.
10. Nodes get the instructions and they stop and remove containers.
At all times there can be external services interacting with researchers,
server, nodes and slivers, e.g. to help choosing nodes, monitor nodes or
collect results.
* Community-Lab integration in existing community networks
# CN diagram (buildings and cloud).
A typical CN looks like this, with most nodes linked using cheap and
ubiquitous WiFi technology (and less frequently Ethernet, optical fiber or
others). The CONFINE project follows three strategies taking into account
that CNs are production networks with distributed ownership:
# CN diagram extended with CONFINE devices (hover over interesting part).
- Take an existing node owned by CN members, CONFINE provides a RD and
connects it via Ethernet to the CD. Experiments are restricted to the
application layer unless the node owner allows the RD to include a direct
interface (i.e. antenna).
- Extend the CN with complete nodes, CONFINE provides both the CD and the RD
and uses a CN member's location. All but low-level experiments are possible
using direct interfaces.
- Set up a physically separated cloud of nodes, CONFINE extends the CN with a
full installation of connected nodes at a site controlled by a partner
(e.g. campus). All kinds of experiments are possible using direct
interfaces. Users are warned about the experimental nature of the network.
* Recap
- Community networks are an emerging field to provide citizens with
connectivity in a sustainable and distributed manner in which the owners of
the networks are the users themselves.
- Research on this field is necessary to support CNs' growth while improving
their operation and quality.
- Experimental tools are still lacking because of the peculiarities of CNs.
- The CONFINE project aims to fill this gap by deploying Community-Lab, a
testbed for existing community networks.
# Commenters: Less attention on architecture, more on global working of
# testbed.
# Ivan: Describe simple experiment, show diagram (UML-like timing diagram?
# small animation?) showing the steps from slice creation to instantiation,
# activation, deactivation and deletion for that example experiment.
# Axel: Maybe the difference of push and pull can be a bit hidden since
# concepts of allocation and deployment remain somehow.
# Ivan: Explain sliver connectivity options using a table with examples ("for
# this experiment you can use that type of sliver interface").
# Axel: I think there are also many figures and lists in the paper that can be
# reused as buzzwords.
# Axel: For example its nice if RDs, sliver connectivity, experiment
# status,... can be instantly demonstrated using globally routable IPv6
# addresses to anybody without having to prepare complex tunnels. These are
# attractive advantages of our design/implementation over PlanetLab and we
# should make use of it and exploit them in demonstrations, dissemination,
# open-call...
# Ivan: We may show more or less the same presentation in the upcoming SAX
# 2012 (Tortosa, September 29-29). We may add (or dedicate more time to) a
# couple of points more related with Community Networks, namely the Open Call
# and how to participate in Community-Lab.
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