Problems faced - Kushagram/wireless-testbed GitHub Wiki

Issues with connectivity

• After setting up the AP and the clients next step is to check whether the configured network is able to communicate with each other or not. However say we ping from the client to the AP and receive the message

Destination Host Unreachable

then it implies the ping request from the client cannot find its route to the destination host.Following might be the reasons for this:

• Actually when the packet is transmitted it first reaches the default gateway and thereafter it reaches the remote gateway.This remote gateway does not have any route to the destination host listed in it(i.e the IP address of the desired host in its routing table) and hence the above message is displayed.

• The destination host might be down.

• The packet reaches the destination network but fails to find the the path to the destination host.

In a similar fashion I had set up one AP(which was opened up in two terminals) and one client. On the first erminal of AP I ran the following command:

ifconfig wlan0 up

create_ap - c 1 -n wlan0 wireless1 secretpassword

Thereafter on the second AP terminal I set up the IP address by running the following command:

ifconfig wlan0 10.10.10.1

Thereafter on the client's terminal I entered the following commands:

wpa_passphrase wireless1 secretpassword > wpa.conf

wpa_supplicant -iwlan0 -cwpa.conf -B

Now when I checked for the connectivity issue by pinging to node1-1 i.e. the Access Point:

ping -c 1 10.10.10.1

The output was:

PING 10.10.10.1 (10.10.10.1) 56(84) bytes of data.

From 10.10.10.2 icmp_seq=1 Destination Host Unreachable

--- 10.10.10.1 ping statistics ---

1 packets transmitted, 0 received, +1 errors, 100% packet loss, time 0ms

When I ran the ifconfig command on node1-1 corresponding to the terminal of AP1 to verify that the IP address and subnet are what I think they are since interfaces can lose or change their IP address if there are multiple background processes all trying to control the interface at the same time.

What I indeed found out was that if I was running:

ping -c 1 10.10.10.1

on the terminal of node1-2 then it showed that Destination host was unreachable.

But on running

ping -c 1 10.40.1.1

where 10.40.1.1 is the IP address of eth1 interface on AP.

This IP address of eth1 interface can be found by running ifconfig on all the nodes.

Hence I think that wlan0 is no longer the interface therefore the IP address of eth1 would be used for all the communication between any pair of nodes.

Now I was planning to proceed with the IP address of this eth1 interface instead of wlan0, so I wanted to know whether it would cause any issues as was the case when I had used the node name for sending data packets.