Provisioning Root Server Recovery Mode; Benefit Of Using Root Server Recovery; Root Server Recovery Vs. Root Recovery - Symmetricom TimeCreator 1000 User Manual

Provisioning Root Server Recovery Mode

Root Server Recovery is Symmetricom's enhancement to the DOCSIS Timing
Interface (DTI) Specification which allows a root server to re-align its subtending
servers in a timely and orderly fashion, without network interruption.
Root Server Recovery consists of two separate mechanisms:
1. Root Server automatically switching to client mode to acquire time and phase
from a subtending server
2. Root Server returning to server mode and slowly steering the subtending servers'
time and phase back in phase with the root
With the TimeCreator 1000, when the root server has lost power or is taken off line
for servicing, the subtending servers' clocks will enter the holdover state and slowly
drift over time. When the root server is restored and has warmed up, it will
automatically switch to a DTI Client role and acquire the time and phase from a
subtending server connected Port 12. The root server will then switch back to its
role as server and use this time and phase to steer the remaining subtending
servers time and phase. Clients connected to the subtending server will also slew
with the subtending server. If the subtending servers are forced to slew their time
and phase too rapidly, however, this may cause modems to re-range, resulting in
service disruption. Root Server Recovery can be configured to slew at a slow rate
that avoids service disruptions.

Benefit of Using Root Server Recovery

Root Server Recovery minimizes service disruption caused by root server outage,
thus improving network availability.

Root Server Recovery vs. Root Recovery

The way the root server recovers is based on the TOD Source mode in which it is
operating. When the root server is in USER TOD Source mode and auto recovery is
enabled, Root Server Recovery mode is used. When the root server is in GPS, NTP,
or RTC TOD Source mode, Root Recovery mode is used.
recovery mode for all TOD Source modes.
In Root Server Recovery mode, the root is switched from server to client mode, thus
allowing it to acquire TOD and phase data from a subtending server. The root is
then switched back to server mode, allowing it to steer the subtending servers time
and phase. Automatic root server recovery is only available for the USER TOD
Source mode, as shown in
Root Server Recovery.
Server Recovery.
097-93100-01 Revision C – February, 2010
Figure 5-1. Figure 5-2
Figure 5-3 shows a larger scale deployment with Root
Chapter 5 Provisioning
Provisioning Root Server Recovery Mode
Table 5-6 shows the
shows a simple deployment with
TimeCreator 1000 User's Guide 95