The answer depends on the location of your two PBX’s. If the two PBX’s are located on the same subnet, then
- Move IP: Use the VoIPNIC option of HAAst to move a single IP between peers. This will allow for rapid reconnection of downstream (user agents) and upstream (trunks)
If the two PBX’s are located on different subnets (from each other):
[list=2]
[*]SRV records: Assuming your user agents (phone sets) support SRV records (which most do), then you should create SRV records for your two PBX’s. Most user agents will perform a DNS lookup for SRV records to find available PBX’s, and try them in order of priority until they successfully register with a PBX. For example, if you have PBX’s located in data centers dc1 and dc2, create two DNS entries (in your internal DNS server) as follows:
type=srv
name=_sip._udp.mydomain.com
priority= 10
weight=0
port=5060
hostname=pbx1.local
and
type=srv
name=_sip._udp.mydomain.com
priority= 20
weight=0
port=5060
hostname=pbx2.local
[*]Route Change: Use the pre/post Asterisk start/stop event handlers of HAAst to update routes in your router(s). Set the updated routes to point to the new PBX address.
[*]DNS update: Use the pre/post asterisk start/stop event handlers to update a public DNS entry. Be sure to set the TTL value low enough that phones will lookup the new IP in a reasonable timeframe.[/list]
Note: Using SRV records or DNS entries makes it easy for users with softphones to move on and off LAN and resume a PBX connection without manual intervention.
