05-27-2010 01:55 PM - edited 03-15-2019 10:59 PM
Does anyone have the actual configuration examples for enabling DNS SRV in CUCM and CUP 7.x to support high availability? I have read through all the Cisco docs which seem to be lacking in specific CUCM/CUP configuration examples and which, if any service parameters in CUP need to be changed.
Thanks,
Jeremy.
05-27-2010 02:29 PM
It depends on what "example" are you looking for.
Cisco does not have documentations on SRV examples because it's actually out of Cisco scope.
Basically, you may treat SRV as a container for multiple A records with additional information like priority, service ports, etc. See http://en.wikipedia.org/wiki/SRV_record
If you have two CUPS servers, cup1.acme.local and cup2.acme.local, you would configure SRV record like below:
_sip._tcp.acme.local. 86400 IN SRV 10 60 5060 cup1.acme.local.
_sip._tcp.acme.local. 86400 IN SRV 10 20 5060 cup2.acme.local.
For explanation of the numbers above, see Wiki.
Michael
http://htluo.blogspot.com
05-27-2010 02:35 PM
I have all the DNS info configured, was more looking for what gets added to CUP / CUCM...
1. Obviously in CUCM, DNS SRV needs to be selected for the CUPS SIP trunk, but does it need the FQDN with the service/protocol or without? Also does it use TCP or UDP on port 5060?
2. In CUP do any service parameters need to be updated, such as setting the balancing to SRV and populating the domain proxy field with the DNS SRV entry and if so, which FQDN?
3. The CUPs presence gateway settings would be changed to the DNS SRV, but does it need the TCP or UDP FQDN? And which FQDN type - with the service/protocol or without?
Thanks,
Jeremy.
05-27-2010 02:41 PM
1. Obviously in CUCM, DNS SRV needs to be selected for the CUPS SIP trunk, but does it need the FQDN with the service/protocol or without? Also does it use TCP or UDP on port 5060?
[Michael] In CUCM, you use the SRV record. In our example, that would be "_sip._tcp.acme.local" (without quotation marks). You don't specify ports. Because the ports are specified in the SRV record itself.
2. In CUP do any service parameters need to be updated, such as setting the balancing to SRV and populating the domain proxy field with the DNS SRV entry and if so, which FQDN?
[Michael] No configuration required on CUP.
3. The CUPs presence gateway settings would be changed to the DNS SRV, but does it need the TCP or UDP FQDN? And which FQDN type - with the service/protocol or without?
[Michael] I don't think CUP presene gateway supports SRV. I'll double check.
Michael
05-27-2010 03:26 PM
I have the presence gateway configured as a SIP SRV record in CUPS 7.0(8) and the help documentation specifies that an SRV record is supported. I have it as "_sip._tcp.domain.domain.local"
Presence Gateway: FQDN, DNS SRV FQDN, or the IP address of the associated Cisco Unified Communications Manager server or Microsoft Exchange server.
06-17-2011 12:06 PM
hi micheal
i am integrating cucm with cups, as far as i know with dns srv i have entered following information
domain=rabbit.com
service=_sip
protocol=_tcp
priority=0
weight=100
port number= 5060
host offering this service=cups
this srv record _sip._tcp._rabbit.com i have entered in cucm sip trunk page.
now in cups i have to add srv record for service pointing to cucm, this is what i have enterered.
domain=rabbit.com
service=_sip
protocol=_tcp
priority=0
weight=100
port number= 5060
host offering this service=cucm
now when i add srv record i am getting error.
"Presence Gateway - value must be either a valid Hostname or IP address."
now let say if it does allow me to enter the srv record, how it will decide which host to go to. cups or cucm.
regards
06-17-2011 04:36 PM
It depends on what version of CUPS you are using. From what I remember in the latest releases you need to use simply the fqdn name without the _sip._tcp part.
It is always recommended to put these records in a subdomain so as to avoid any conflicts with any other srv records configured.
HTH,
Christos
06-17-2011 04:48 PM
hi chirs
first thanks for your reply
i am using cups 8.5 and cucm 8.5
do you recommend using srv or FQDN for sip trunk and presence gateway.
As for the first part, if i decided to use srv, my entry in dns should look like this.
domain=cups.rabbit.com
service=_sip
protocol=_tcp
priority=0
weight=100
port number= 5060
host offering this service=cups
and for cucm
domain=cucm.rabbit.com
service=_sip
protocol=_tcp
priority=0
weight=100
port number= 5060
host offering this service=cucm
correct me if i am worng.
regards,
note: in the presence gateway configuration help it does say to use srv record.
06-17-2011 04:45 PM
SRV records do not work the way you have configured them. At each domain level only one product (e.g. CUCM or CUP) can use that SRV service for a particular protocol (e.g. SIP). It will not work as you have it because you have created SRV records for _sip._tcp and pointed it to two separate products!
You need to create subdomains for each product. Here's the output of one working example using nslookup:
Here are the records for CUP. Note that they are in the subdomain presence.uc.domain.com.
Based on this you would enter "_sip._tcp.presence.cluster1.uc.domain.com" into the Destination Address of the SIP Trunk in CUCM and check the SRV checkbox.
nslookup
set type=srv
_sip._tcp.presence.cluster1.uc.domain.com
Server: dns-server.domain.com
Address: 10.242.40.64
_sip._tcp.presence.cluster1.uc.domain.com SRV service location:
priority = 10
weight = 0
port = 5060
svr hostname = presence2.cluster1.uc.domain.com
_sip._tcp.presence.cluster1.uc.domain.com SRV service location:
priority = 10
weight = 0
port = 5060
svr hostname = presence1.cluster1.uc.domain.com
presence2.cluster1.uc.domain.com internet address = 10.245.250.58
presence1.cluster1.uc.domain.com internet address = 10.245.250.57
Here are the records for CUCM. Note they are in the subdomain uc.domain.com.
Based on this you would enter "cluster1.uc.domain.com" into the presence gateway on the CUP server.
nslookup
set type=srv
_sip._tcp.cluster1.uc.domain.com
Server: dns-server.domain.com
Address: 10.242.40.64
_sip._tcp.cluster1.uc.domain.com SRV service location:
priority = 10
weight = 0
port = 5060
svr hostname = manager5.cluster1.uc.domain.com
_sip._tcp.cluster1.uc.domain.com SRV service location:
priority = 10
weight = 0
port = 5060
svr hostname = manager6.cluster1.uc.domain.com
manager5.cluster1.uc.domain.com internet address = 10.245.250.37
manager6.cluster1.uc.domain.com internet address = 10.245.250.38
PS- Christos is correct. The behavior appears to have changed in recent CUPS versions; it no longer wants _sip._tcp in the URL even though this isn't clearly documented.
06-17-2011 04:55 PM
Great example. I couldn't have written it better!
On top of the above just watch out for the following defect which you will probably hit when using SRV records
CSCth25928
Callmanager will never try the second SRV record if the primary CUPS is down
Doesn't look it's fixed yet.
Regards,
Christos
06-17-2011 05:08 PM
Wow. How/why is that classified as an enhancement request and not an defect?! That essentially renders all SRV usage on CUCM completely pointless!
01-03-2012 11:05 PM
Does this bug make CUPS HA pointless as DNS SRV is required for the functionality being described throughout this thread?Two sites with both a CUCM and CUP, and the active site goes down. Will the presence gateway work?
I understand the Jabber/CUPC clients will failover to the second CUPS server but then there is no Presence gateway for soft and hard phone and presence status.
Has this been resolved in 8.6 latest? The bug does not indicate such and I opened a TAC case to see but wanted to see if anyone has been successful in a CUCM/CUPS failover.
Thanks
01-16-2012 11:23 AM
Did you happen to get a response from TAC whether the bug is resolved?
05-15-2012 11:54 AM
As of today May 15, CSCth25928 is not resolved. I recommend using the bug toolkit to track the progress of any bug. Here's a link for your convience.
There is now a workaround in the bug.
Workaround:
Configure two A records that point to the CUPS pub and sub by configuring a
dummy fqdn in DNS where the cucm sip trunk is pointing at. This dummy fqdn
resolved into 2 ip addresses.
Now the caveat is that you have to configure this fqdn in the cup sip proxy
service parameter
Server Name (supplemental)
In order for cup server to recognize that this fqdn is destined for CUP
otherwise we endup in a loop.
-- Joseph Hardy
06-06-2012 12:20 PM
So if I'm understanding this correctly, the Destination is an SRV option for a SIP trunk in CUCM is nothing more than a cosmetic button? It actually doesn't work until the feature is "enhanced"??
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