I have two linux based machine (different kernel version), say A and B. B is a freescale board on which i installed linux-3.0.35 and usb ncm gadget driver. I am trying to ping one machine by another via USB.
I am able to ping B from A. But unable to ping A from B.

Routh table of machine A is (ip address 192.168.5.2)

Destination Gateway enmask Flags Metric Ref Use Iface

192.168.5.0 * 255.255.255.0 U 0 0 0 usb0

Routh table of machine B is (ip address 192.168.5.1)

Destination Gateway enmask Flags Metric Ref Use Iface

192.168.5.0 * 255.255.255.0 U 0 0 0 usb0

any guess about the problem ??

Can you do a nslookup on each machine for other one. And what does /etc/hosts say?

"I am able to ping B from A. But unable to ping A from B."

When you issued command ping to A, the ping left B and went to A. It then was allowed to reply back to B. The connection was fully tested both ways.

That single ping proved that both sides did in fact transmit and receive. Ping is a two way connection in order to pass. It is also a poor choice for most uses anymore.

Since we know both systems are connected as proved by a single passing ping we then need to look at ways one system would deny local use or remote use.

Yes ping inot a good way to test connection. In ping response comes on the same path by which it goes A to B. So sometimes A to B ping is possible but B to A has some problem . I open TCp socket and tried to write some data. I am able to do both read and write opearation. I think problem is in NCM gadget driver. Thanx for the help