I have an issue pinging from one host to another using Cisco 2600 routers.   I can ping from a host throught router A across the t1 to router B's e0/0 port and then the ping stops. This happens going both ways.  Attached below is one runnning conf...

   I am currently studying for the CCNA exam and have a simple PPP Issue.   Host A-100.100.100.3/24   Router 1 - e0/0-100.100.100.252/24,  s0/0-172.16.1.100/24, s0/0 is a t1 curcuit.Router 2 - e0/0-100.100.1.253/24, s0/0-172.16.1.101/24, s0/0 is a t1...