Troubleshooting Notes #3
CRCX
I’m on a roll tonight. Here are some more troubleshooting/FYI notes, this time focused on SRST. The study life of a dedicated CCIE candidate is one constant stream of information absorption occasionally interrupted by family time, eating, sleeping, and relieving oneself in the bathroom. Sometimes the latter gets delayed by long chapters on gatekeeper behavior (as I’m experiencing right now!).
DLCX
Be aware of the following SRST restrictions:
- Extension mobility does not work in SRST mode when using call-manager-fallback. CME as SRST does have extension mobility, but login information is not seamlessly transferred during failure situations.
- SRST does not have a concept of partitions or calling search spaces. CoR can be used to some extent, but it is a weak-comparison and is not automatically populated on the SRST router.
- MWIs might be out of synch when recovering from SRST mode.
- All forwarding (busy, no answer, and forward all) is lost in SRST mode.
- In SRST mode, all call routing decisions are made on the SRST gateway through dial peer configuration, so anything not explicitly configured on the SRST gateway will not work.
For SRST mode, be sure to configure voicemail under “telephony-service” and to configure an “ephone-dn template” to set the necessary call-forward noan and busy behaviors.
Set your DHCP lease times to several days, or use a local DHCP server to ensure that IP Phones do not reset themselves when their lease expires during a WAN outage.
Use transfer patterns to allow transfers to non-IP Phone destinations.
