Community-Lab introduction

Modified script.txt from [1a6ed75dc5] to [d52f0b2d78].

    98     98     - Avoids problems with firewalls and private networks in nodes.
    99     99     - Uses IPv6 to avoid address scarcity and incompatibility between CNs.
   100    100     - Mgmt connections are short-lived to tolerate link instability.
   101    101   - Gateways are entry points to the mgmt network.
   102    102     - They help extend it over multiple CNs by external means (e.g. FEDERICA, the
   103    103       Internet).
   104    104     - They can also route the management network to the Internet.
   105         -- Researchers run experiments in slices spread over several nodes (as
   106         -  slivers). *##*
          105  +- Experiments are configured by researchers in the server and run in nodes. *##*
   107    106   
   108    107   ** Slices, slivers and nodes
   109         -# Axel: Reverse, from PoV of researcher: select nodes, run as slivers, gruop in slices.
   110         -- These concepts are inspired in PlanetLab.
   111         -- A slice is a management concept that groups a set of related slivers.
   112         -- A sliver holds the resources (CPU, memory, disk, bandwidth, interfaces…)
   113         -  allocated for a slice in a given node.
   114         -- A node hosts several slivers at the same time. *##*
          108  +- Particularly, researchers select nodes for running experiments.
          109  +- Each node is able to run several experiments simultaneously.
          110  +- An experiment runs in a given node as a sliver which holds a share of its
          111  +  resources (CPU, memory, disk, bandwidth, interfaces…).
          112  +- Finally, related slivers are grouped in a slice for management purposes.
          113  +- All these concepts are inspired in PlanetLab. *##*
   115    114   
   116    115   ** Node architecture
   117    116   # Axel: More stress on node itself.
   118    117   # Ivan: Don't zoom!!
   119    118   allows the realization of these concepts.  *##* A node consists of a CD, a RD
   120    119   and a rD connected to the same wired local network. *##*
   121    120