Linux tips and other things…
If you get this message on logs:
VFR-4-FRAG_TABLE_OVERFLOW: Dialer0: the fragment table has reached its maximum threshold 16
usually indicates than you are receiving a high number of fragmented packets. It may happens using p2p applications like torrent or emule, under an fragmentation packet attack or another causes.
You can increase this value and check if warnings disappear:
router(config-if)#ip virtual-reassembly max-reassemblies 64
Enter in config mode:
router#configure t
First configure a DNS server to resolve ntp servers name:
router(config)#ip name-server 8.8.8.8
Now set a primary ntp server:
router(config)#ntp server 0.europe.pool.ntp.org
And also a secondary:
router(config)#ntp server 1.europe.pool.ntp.org
Finally configure the time zone, here CET + 1:
router(config)#clock timezone CET 1
Exit from configuration mode and test the status, usually is necessary to wait for a few minutes to get a successful synchronization. Output can be similar to this:
router# show ntp status Clock is synchronized, stratum 3, reference is 178.16.23.50 nominal freq is 249.9684 Hz, actual freq is 249.9665 Hz, precision is 2**16 reference time is DA07DA35.B8AE53C5 (15:40:20.721 CET Tue Ago 4 2015) clock offset is -0.0009 msec, root delay is 0.11 msec root dispersion is 0.08 msec, peer dispersion is 0.01 msec loopfilter state is 'CTRL' (Normal Controlled Loop), drift is 0.000007607 s/s system poll interval is 1024, last update was 567 sec ago.
And test the association server status too:
router# show ntp associations address ref clock st when poll reach delay offset disp *~178.16.23.50 75.12.230.181 2 907 1024 377 86.323 -0.927 13.845 ~37.247.53.178 129.242.4.241 2 904 1024 377 86.323 -0.927 14.845 * sys.peer, # selected, + candidate, - outlyer, x falseticker, ~ configured