Dear Mohammad,
It isn't clear whether you have 3 different configuration files or not, so let's make sure you have them.
You didn't give info on node 3 either.
Node 1 should have a conf file with :
#Connected to node 2
static1_address = 192.168.10.12
static1_uri = dtn://dtn-node2.dtn
static1_proto = tcp
Node 2 should have a conf file with :
#Connected to Node 1
static1_address = 192.168.10.11
static1_uri = dtn://dtn-node1.dtn
static1_proto = tcp
# Connected to Node 3
static2_address = 192.168.10.13
static2_uri = dtn://dtn-node3.dtn
static2_proto = tcp
Node 3 should have a conf file with :
#Connected to node 2
static1_address = 192.168.10.12
static1_uri = dtn://dtn-node2.dtn
static1_proto = tcp