098-00720-000 Revision B – April, 2016
SyncServer 600 Series User’s Guide
85
Chapter 4
Navigation Windows
It is important to note that NTP is UDP/IP and is by nature susceptible to DoS
attacks as no TCP/IP connection is required. The Security-Hardening of the line
speed NTP Reflector is such that in the event of an NTP DoS attack the NTP
packets will not reach the CPU and compromise the server operation. Instead, all
NTP packets can be responded to (or limited) and if the NTP load is in excess of
what is expected an alarm is sent notifying the user. The alarm threshold can be set
on the packet monitoring page, which is part of the Security section tab..
When changing the configuration between IPv4 and IPv6, the reflector will be
disabled for up to 15 seconds. During this time, the traffic will be forwarded to the
CPU. If the traffic rate exceeds the all-packets threshold, then the traffic will be
dropped and an alarm generated.
Note:
There is a 1 microsecond bias compared to the S6xx clock
accuracy when using the NTP Reflector at 100BaseT speeds. This
bias will be largely undetectable by any NTP client, but the bias
should be removed in a future release.