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Internet connections interrupted

Last Modified: 2012-08-15
Hello all,

This is long, please bear with me.

For the past week we have been having severe latency and interruptions to our internet connectivity.  Messages from R-U-0n and MxWatch show that periodically our resources are unreachable online, the timing varies.  We have an MPLS network and all sites are affected, though it seems that the main site is affected more.   I have removed our own firewall from the mix.  That did not solve the problem.  The ISP has their own FrontLine firewall.

These interruptions affect computers in any switch.  Switch diags show no errors or packet loss.WireShark reports 0 errors. Resources inside the LAN are not affected, all servers and printers are available as usual while the Internet interruptions occur.  

Current example:  A continuous ping to the natted address from outside to Server A times out (5 times) and then comes back for one reply, then repeats, in that pattern, 5 off, one on, with little variation.  Continuous ping to Server A from Server B from inside the LAN replys in <1ms with no timeouts at all. Both servers are in the same gigabit switch. Could this still happen if the switch, a port or the cable were bad?   I was able to remote to the Server B at the same time i was unable to remote to Server B.  After about 20 minutes I got disconnected from Server B, then after a few minutes it was available again.  I am able to remote to the Server A from my Server B session inside the LAN with no issues.

Our ISP says there are no errors on the circuit, however Verizon came to fix what they said was a circuit problem on 7/31 (they did not touch the data room, only the demarc), and it was right after they left that the constant monitoring messages began.  

Any ideas on what could be causing the problem would be appreciated.
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