The Out-of-dialog (OOD) Options Ping feature provides a keepalive mechanism at the SIP level between any number of destinations.
A generic heartbeat mechanism allows Cisco Unified Border Element to monitor the status of SIP servers or endpoints and provide
the option of busying-out a dial-peer upon total heartbeat failure. When a monitored endpoint heartbeat fails, the dial-peer
is busied out. If an alternate dial-peer is configured for the same destination pattern, the call is failed over to the next
preferred dial peer, or else the on call is rejected with an error cause code.
The table below describes error codes option ping responses considered unsuccessful and the dial-peer is busied out for following
scenarios:
Table 1. Error Codes that busyout the endpoint
Error Code
|
Description
|
503
|
service unavailable
|
505
|
sip version not supported
|
no response
|
i.e. request timeout
|
All other error codes, including 400 are considered a valid response and the dial peer is not busied out.
Note |
The purpose of this feature is to determine if the SIP session protocol on the endpoint is UP and available to handle calls.
It may not handle OPTIONS message but as long as the SIP protocol is available, it should be able to handle calls.
|
When a dial-peer is busied out, Cisco Unified Border Element continues the heartbeat mechanism and the dial-peer is set to
active upon receipt of a response.