| 207 | [[Image(exp1.png)]] |
| 208 | |
| 209 | and |
| 210 | |
| 211 | [[Image(exp2.png)]] |
| 212 | |
| 213 | Because each testbed only knows about the resources it has committed to the federated experiment, these representations are incomplete. Even the two virtual testbeds on DETERLab do not include information about the other testbed. |
| 214 | |
| 215 | It can be instructive to see how the federation system interconnects these experiments. |
| 216 | |
| 217 | Logging into node {{{d}}} in the {{{deter/exp2}}} sub-experiment, inspecting the routing table shows: |
| 218 | |
| 219 | {{{ |
| 220 | d:~$ ip route |
| 221 | default via 192.168.1.254 dev eth1 |
| 222 | 10.0.0.0/24 dev eth2 proto kernel scope link src 10.0.0.1 |
| 223 | 10.0.1.0/24 via 10.0.0.2 dev eth2 proto zebra metric 30 |
| 224 | 10.0.2.0/24 via 10.0.0.2 dev eth2 proto zebra metric 30 |
| 225 | 10.0.3.0/24 via 10.0.0.2 dev eth2 proto zebra metric 20 |
| 226 | 10.0.4.0/24 via 10.0.0.2 dev eth2 proto zebra metric 20 |
| 227 | 192.168.0.0/22 dev eth1 proto kernel scope link src 192.168.3.144 |
| 228 | 192.168.252.0/22 via 192.168.1.254 dev eth1 proto zebra |
| 229 | }}} |
| 230 | |
| 231 | There are routes in the table to hosts that are not in the DETERLab experiment. Specifically none of 10.0.0.0/24, 10.0.3.0/24 or 10.0.4.0/24 are present in the {{{TIED/fed1-exp2}}} experiment that contains {{{d}}}. |
| 232 | |
| 233 | The federation system has done 4 things to make it possible and simple for the sub-experiments to communicate. |
| 234 | |
| 235 | * The [NewFeddAbout#TheExperimentController experiment controller] assigned consistent network (IP) addresses to the experiment nodes. |
| 236 | * The controller configured and started [http://en.wikipedia.org/wiki/Open_Shortest_Path_First ospf] routers on each machine to propagate routes between the two experiments. |
| 237 | * The controller interconnected the two experiments through a local VLAN (by coordinating with a third virtual testbed) |
| 238 | * Entries for the nodes in the other experiment were added to {{{/etc/hosts}}} so symbolic names can be used to reach nodes allocated in either experiment. |
| 239 | |
| 240 | Similar work can be done to present unified login information and shared filesystems. That is not done in this case because the experiments are both in the same DETER project and testbed. |
| 241 | |