An engineer is troubleshooting this situation: -> The MPLS connection between site A and site B is flapping in intervals of 30 seconds at least twice an hour.
-> Phones at site B fail over to their Survivable Remote Site Telephony configured gateway.
-> Phones fail back to their primary Cisco Unified Communications Manager server as soon as the connection is reestablished.
-> Phones fail over again to SRST.
Which UCM setting allows the phones to stay in SRST for a longer period of time before falling back to Cisco Unified CM?
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A. B. C. D. E.Explanation.
The situation described in the question indicates that there is a problem with the MPLS connection between Site A and Site B, causing the connection to go down and come back up every 30 seconds at least twice an hour. As a result, the phones at Site B fail over to their Survivable Remote Site Telephony (SRST) configured gateway and then fail back to their primary Cisco Unified Communications Manager (UCM) server as soon as the connection is reestablished. However, the phones fail over again to SRST, which indicates that the connection is still unstable.
To resolve this issue, the engineer needs to adjust a UCM setting that allows the phones to stay in SRST for a longer period of time before falling back to Cisco Unified CM. The options provided are:
A. Maximum Phone Fallback Queue Depth B. Connection Monitor Duration C. Keepalive Timeout Timer D. Station KeepAlive Interval E. T302 Timer B.
Out of these options, the one that is related to the phones staying in SRST for a longer period of time is the "Connection Monitor Duration" setting (option B). The Connection Monitor Duration setting determines how long the phone will stay registered to the SRST gateway before attempting to re-register with the primary UCM server. By default, this setting is set to 120 seconds. By increasing this setting, the phones will stay registered to the SRST gateway for a longer period of time, allowing more time for the MPLS connection to stabilize.
The other options listed are:
A. Maximum Phone Fallback Queue Depth: This setting determines the maximum number of phones that can be queued for fallback to SRST. It does not affect the duration that phones stay in SRST.
C. Keepalive Timeout Timer: This setting determines the amount of time that the UCM server waits for a response from a phone before considering it unreachable. It does not affect the duration that phones stay in SRST.
D. Station KeepAlive Interval: This setting determines the frequency at which the phone sends keepalive messages to the UCM server. It does not affect the duration that phones stay in SRST.
E. T302 Timer B: This setting is related to the Session Initiation Protocol (SIP) protocol and determines the amount of time that the UCM server waits for a response to a SIP message. It does not affect the duration that phones stay in SRST.
In conclusion, to allow the phones to stay in SRST for a longer period of time before falling back to Cisco Unified CM, the engineer should adjust the "Connection Monitor Duration" setting in UCM.