SRG phones stuck in local mode

[carentan1944]

I have a number of SRGs registered to a CS1000 running 4.0 I am finding that if I get a network issue various phones on the SRGs get stuck in local mode and the only way to get them to register to the main office is to reboot the SRG. The SRGs sre running on 3.6 s/w.
Has anyone had similar problems or can explain why this should happen. Your help would be very much appreciated.

 

[thattekguy]

There is a known problem with this when there is a WAN outage,upgrade,reboot, there is some patches for this.
SRG200/400 1.5 beta patches, or something like that.If you can't find them I will look for them and list them out for you.

 

[thattekguy]

See if this might be your issue.
SRG 1.0, 1.5 or SRG50 is configured to a CS1000 Main Office. The telephones are in Normal Mode (redirected to the Main Office).

Though there has been no WAN failure, it has been reported that some or all SRG telephones go into Survivable Mode (Local Mode). Once in this condition, the telephones do not redirect themselves back to the Main Office but rather have to be manually redirected using Element Manager or Unified Manager as applicable or by power-cycling the IP telephone itself.

One known cause of this issue is packet loss in the network which causes the watchdog timer to expire. If the watchdog timer is exceeded, this causes the IP telephone to "reset". This is design intent.

Scenario:
IP telephones use the RUDP (Reliable UDP) layer to detect WAN Failure.
RUDP requires an ACK for each message sent to the TPS (in this case, the Main Office TPS).
If no ACK is received for a given message (a watchdog timeout event or user input), then the IP telephone retries the message transmission.
If there is no response after N retries, the IP telephone enters the TPS Acquisition process and tries to reestablish RUDP session with the current TPS.
The telephone displays “Server Unreachable – Retrying”.
This extends the provisioned “Retry Count” number of times.
If unsuccessful, the IP telephone waits 1.5 to 2.5 minutes (random distribution) and tries to establish a RUDP session with the provisioned S1 (which is set to the SRG).
Since SRG is reachable, the RUDP session is established and the IP telephone is booted in local mode on the SRG.
Call forward of local FTE is cancelled automatically and the IP telephone can access local resources, (including PSTN) as provisioned.
Note: Telephones cannot distinguish among WAN failures, routing issues, or main office TPS failures.
In this case, the problem is not due to a WAN failure but rather because of the lack of an acknowledgment received from the Main Office within the allotted time (the watchdog timer is 200 seconds).
Redirected telephones exchange more messaging with the TPS than does a telephone which is directly connected to the MO in order to reliably fall back into survivable mode in the event of network issues. This is the intention and the design of survivability.
Problem Resolution
Determine if the IP telephones are resetting because of a watchdog timeout. This can be done by checking the IP telephone status in the CS1000. If the last reset reason seen in the CS1000 is watchdog timer expiry, then the packet loss is likely occurring in the network.

Isolate and correct the the source of the packet loss in the network.