Why usrp Receiver get error packets at receiving end?

Hi,

I tried to send ping between two system using tunnel.py.

When I run the tunnel.py, it shows,

UUTIMEOUT
Tx: len(payload) = 90
Rx: ok = False len(payload) = 90
UUTx: len(payload) = 54
UUTx: len(payload) = 214
URx: ok = False len(payload) = 214
UTx: len(payload) = 319
URx: ok = False len(payload) = 319
UTx: len(payload) = 319
Rx: ok = False len(payload) = 319
UTx: len(payload) = 319
Rx: ok = False len(payload) = 319
UTx: len(payload) = 78
UUTx: len(payload) = 295
Rx: ok = False len(payload) = 295
UUTx: len(payload) = 214
URx: ok = False len(payload) = 214
UTx: len(payload) = 90

At the receiving end the packets not received properly, I got Rx
OK=false.

I changed the min_delay=0.05 to 0.1 , but same problem I got.
I am using USRP1., gr0 up and assigned IP address.

Can anyone faced like this.

Thank you,

KR