For us Cisco techs, one of the more often than not nowadays is that have to deal with the MS world of DNS (AND Certifciate Architecture… I’ll talk about this in later articles). I’ve had a fair bit of experience with DNS in the past, so I thought I would just share a little about integrating CUCM with IM & Presence using SRV records both ways to support CUCM Clusters and IM & Presence Clusters for high availability.
DNS Configuration
Create A (Host) Records
CUCM DNS A Records
Type | Hostname | IP Address |
A | cucm01.uplinks.com.au | 192.168.0.20 |
A | cucm02.uplinks.com.au | 192.168.0.21 |
IM&P DNS A Records
Type | Hostname | IP Address |
A | imp01.uplinks.com.au | 192.168.0.30 |
A | imp02.uplinks.com.au | 192.168.0.31 |
Create SRV Records
IM&P Cluster Name: imp.uplinks.com.au
Type | Identifer | Protocol | Weight | Priority | Host |
SRV | _sip | _tcp | 10 | 10 | imp01.uplinks.com.au |
SRV | _sip | _tcp | 10 | 10 | imp02.uplinks.com.au |
CUCM Cluster Name: cucm.uplinks.com.au
Type | Identifer | Protocol | Weight | Priority | Host |
SRV | _sip | _udp | 10 | 10 | cucm01.uplinks.com.au |
SRV | _sip | _udp | 10 | 10 | cucm01.uplinks.com.au |
Verify Records via NSLOOKUP
> set q-all
> _sip._tcp.imp.uplinks.com.au
> _sip._udp.cucm.uplinks.com.au
The above should output the following results.
- The SRV Records and their target hosts
- An A record for every target host identified in the SRV record.
CUCM Configuration
SIP Trunk
- Navigate to Device, then select Trunks
- Select Add New
- Select SIP Trunk for Trunk Type
- Select Next
- Complete the details of the SIP Trunk as per normal.
- Under SIP Information, check the box Destination Address is SRV
Note: When the checkbox is ticked, CUCM changes the outbound SIP protocol from udp to tcp.
- Type the IM&Presence Cluster Name. (imp.uplinks.com.au)
- Select Save and then reset the Trunk.
Configure SIP Publish Trunk
- Navigate to the Service Parameters, then Cisco CallManager.
- Find “IM & Presence Publish Trunk”
- Drop the arrow down and select the above SIP Trunk.
IM & Presence Configuration
SRV Cluster Name
- Navigate to Service Parameters, then Cisco SIP Proxy.
- Find “SRV Cluster Name”
- Type the IM&Presence cluster name (imp.uplinks.com.au)
- Select Save
Presence Gateway
- Navigate to Presence, then Gateways.
- Select Add New
- Select CUCM for Presence Gateway Type.
- Type a Descriptive note.
- Type the SRV Record for the CUCM Cluster Name.
Note: Do not strip the SRV Identifier or Protocol. Example input would be _sip._udp.cucm.uplinks.com.au