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Chapter 2 Xgig1000 System Setup
Sync Discovery Process
March 2017 Xgig1000 Hardware Guide Page 97
Sync Discovery Process
The Xgig chassis can be cascaded together to form a Sync Group. A Sync Discovery
process is run to establish the Sync Group topology. When Sync Discovery starts, all
connections to the Sync Group will be severed. Port captures may or may not be preserved
depending on each situation. The rules of a Sync Group are:
• The IP addresses of all chassis in the Sync Group must reside on the same subnet.
• All chassis must have the same App Kit version.
The Sync Discovery Process occurs under the following conditions:
• Sync Discovery is done automatically at boot up to learn the topology of the Sync
Group.
• Removing a member from a Sync Group will always cause Sync Discovery to start.
This includes rebooting or shutting down a member within a Sync Group or any inter-
ruption to the management port of any member within the group when the chassis
operating system determines it has lost its IP address. When the Sync Discovery
Process is notified of an IP Address change, it will then start Sync Discovery. For a
Management cable removal, it is usually approximately nine seconds, but this time
could vary.
Examples of IP Address Changes are:
– Original IP address == 10.75.131.10 Then, the Sync Discovery Process is noti-
fied the address has changed to 10.75.131.11
– Original IP address == 10.75.131.10 Then, the Sync Discovery Process is noti-
fied the address has changed to 0.0.0.0 and then back to 10.75.131.10. Sync
Discovery must run in this case, because the chassis has lost communications
with the other chassis, and the Sync Group in is an UNKNOWN State.
• Breaking the Cascade link will always initiate Sync Discovery. The timing is indeter-
minate, as this is not a real time operating system. The thread that detects this runs
every 10ms, but under Windows, this can vary by as much as 20 to 50 milliseconds
or more if a high priority process is utilizing all of the CPU time. Under normal condi-
tions, Sync Discovery will start with in 100 ms, but this cannot be guaranteed.
• Adding member(s) to a Sync Group may start the Sync Discovery. Sync Discovery
will not start if any ports in the group have ever been locked, even if the ports are
unlocked afterward. A Sync Reset operation must be initiated to force a Sync
Discovery operation to start.
• If there are chassis cascaded together, and the master chassis detects it can not
longer communicate with any of the slave chassis, it will initiate Sync Discovery. The
timing on this cannot be stated absolutely. The master chassis tries to connect to the
slaves three times at five second intervals before a failure is declared. The amount of
time this process takes depends on the network. We estimate it takes from 15
seconds to a minute seconds, but it is not possible to pinpoint.
• A Sync Reset can be initiated to re-discover the members within a Sync Group.
When you initiate Sync Reset on one of the sync chassis, it will initiate a group Sync
Reset.This operation can only be done by the administrator via the web utility.