I'm troubleshooting a fractional T1 (16 timeslots) that is having some strange problems. Using extended ping, I gathered the following information:
-Small pings up to 1000 bytes with the default data pattern go across the line with no problems.
-Starting at around 1400 bytes, pings with the default data pattern fail at a rate of about 3 - 5%.
-Pings sized at 1000 bytes with a data patern of 0x0000 fail at a rate of about 3 to 5%
-500 byte pings with a data pattern of 0x0000 go through with no problem.
-1000 byte pings with a data pattern of 0xFFFF go through with no problem.
-Strangley, no errors show in the counters for the interfaces on either side of the link.
The MTU is set at 1500 bytes at both sides. I changed the queueing from WF to FIFO with no change in results. I verified that the settings of the (external) DSU on one side of the link is set correctly (ESF, B8ZS,16 timeslots), but I can access the other end's DSU.
specified somewhere along the path of the circuit. But why would the0x0000 pings fail only for larger packets, and not the smaller sized? Any insight would be greatly appreciated.