docs: Connect Mini-NDN to external network

refs: #3052

Change-Id: I0bb060fc1095946b8f6302880aa78b817a9c07f7

docs/CONNECT-TO-OUTSIDE.md

@@ -0,0 +1,86 @@
+Connect Mini-NDN nodes to an outside network
+============================================
+
+Mini-NDN nodes can be connected to an outside network indirectly by running NFD on the local machine:
+
+    (Mini-NDN node) ------ (NFD running on the host machine where Mini-NDN is running) ------- (External Network)
+
+## Add a node in root namespace
+
+For this simple example, we use the default topology:
+
+    c----a----b----d
+
+If we want node "a" to connect to the host machine, we need to add a "root" node which has a link with
+node "a."
+
+To do so, the following lines can be added to bin/minindn before net.start():
+
+```python
+root = Node( 'root', inNamespace=False )
+net.addLink(root, 'a')
+```
+
+Adding these before net.start() is important as node "root" would then be assigned an IP automatically.
+Re-install Mini-NDN by issuing the following command in the mini-ndn folder:
+
+    sudo ./install.sh -i
+
+## Configuration
+
+Run Mini-NDN with the simple topology and issue ifconfig on the local machine to confirm the addition of
+the interface. You should be able to locate "root-eth0":
+
+    root-eth0 Link encap:Ethernet  HWaddr 3e:eb:77:d2:6f:1f
+              inet addr:1.0.0.9  Bcast:1.0.0.11  Mask:255.255.255.252
+              inet6 addr: fe80::3ceb:77ff:fed2:6f1f/64 Scope:Link
+              UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
+              RX packets:34 errors:0 dropped:0 overruns:0 frame:0
+              TX packets:33 errors:0 dropped:0 overruns:0 carrier:0
+              collisions:0 txqueuelen:1000
+              RX bytes:2667 (2.6 KB)  TX bytes:2797 (2.7 KB)
+
+To make the IP address associated with this interface persistent, add the following line to
+/etc/network/interfaces and reboot your machine:
+
+    iface root-eth0 inet manual
+
+## Check connection
+
+After rebooting, run Mini-NDN and issue the following command:
+
+    mininet>net
+    a a-eth0:b-eth0 a-eth1:c-eth0 a-eth2:root-eth0
+
+Node "a" is connected to "root-eth0". Now issue "ifconfig a-eth2" on node "a":
+
+    mininet>a ifconfig a-eth2
+    a-eth2    Link encap:Ethernet  HWaddr fa:76:d4:86:d3:ba
+              inet addr:1.0.0.10  Bcast:1.0.0.11  Mask:255.255.255.252
+
+As learned from the previous step, the IP address of root-eth0 is 1.0.0.9.
+
+    mininet>a ping 1.0.0.9
+    PING 1.0.0.9 (1.0.0.9) 56(84) bytes of data.
+    64 bytes from 1.0.0.9: icmp_seq=1 ttl=64 time=0.137 ms
+    64 bytes from 1.0.0.9: icmp_seq=2 ttl=64 time=0.123 ms
+
+The host machine will also be able to ping node "a":
+
+    VirtualBox:~$ ping 1.0.0.10
+    PING 1.0.0.10 (1.0.0.10) 56(84) bytes of data.
+    64 bytes from 1.0.0.10: icmp_seq=1 ttl=64 time=0.086 ms
+
+## Run NFD on local machine and register route
+
+Start NFD on the local machine by using:
+
+    sudo nfd
+
+The "nfd-start" script cannot be used, since the script allows only one instance of NFD at a time.
+The NFD processes running on the Mini-NDN nodes will prevent the "nfd-start" script from working.
+
+Now, using "nfdc register", we can register a route from node "a" in Mini-NDN to the NFD process on the
+host machine and from the host machine to an external machine.
+
+Also, if the local machine has a public IP, Mini-NDN nodes can be reached via external machines.