Hello Ovais,
as explained in the document linked by Rakesh pinging your own ip address works differently on wan interfaces then on ethernet interfaces.
LAN interfaces ping themselves without sending a packet on the wire.
Actually if you take an unplugged ethernet of fastethernet you configure
int eth0
ip address 10.10.10.1 255.255.255.0
no keepalive
you can then ping it even if it is unplugged I've used this trick on lab tests some years ago.
With serial interface, ATM, FR the things are different:
pinging your own ip address means the packet is sent out on wires: the icmp echo request reach the remote end DTE that "reflects back" the frame to local router interface.
I saw this clearly the first time I did Netflow tests: by comparing interface counters, SNMP interface counters and Netflow data all was multiplied by 2 when pinging the ip address of an ATM interface from itself.
On all this trip when you do
PPP over FR you cannot solve this by simply mapping on FR your own ip address as it can be done on a FR only multipoint interface.
Because you now have:
IP/PPP/FR you cannot map ip over FR.
to be noted that if you can ping the other side all is well.
By the way you have alternate ways to verify that connectivity is good:
you can check the virtual-template to see if the ipcp phase is in open state meaning a successful IPCP negotiation has been performed on the logical PPP channel.
Hope to help
Giuseppe
