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Beginner

CUP 7 - CUCM 7 & DNS SRV Config

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.

16 REPLIES 16
Engager

Re: CUP 7 - CUCM 7 & DNS SRV Config

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

Beginner

Re: CUP 7 - CUCM 7 & DNS SRV Config

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.

Engager

Re: CUP 7 - CUCM 7 & DNS SRV Config

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

Re: CUP 7 - CUCM 7 & DNS SRV Config

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.

Beginner

Re: CUP 7 - CUCM 7 & DNS SRV Config

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

Re: CUP 7 - CUCM 7 & DNS SRV Config

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

Beginner

Re: CUP 7 - CUCM 7 & DNS SRV Config

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.

Re: CUP 7 - CUCM 7 & DNS SRV Config

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.

Re: CUP 7 - CUCM 7 & DNS SRV Config

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

Re: CUP 7 - CUCM 7 & DNS SRV Config

Wow. How/why is that classified as an enhancement request and not an defect?! That essentially renders all SRV usage on CUCM completely pointless!

Beginner

CUP 7 - CUCM 7 & DNS SRV Config

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

Beginner

CUP 7 - CUCM 7 & DNS SRV Config

Did you happen to get a response from TAC whether the bug is resolved?

Cisco Employee

Re: CUP 7 - CUCM 7 & DNS SRV Config

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.

http://tools.cisco.com/Support/BugToolKit/search/getBugDetails.do?method=fetchBugDetails&bugId=CSCth25928

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

Highlighted
Beginner

CUP 7 - CUCM 7 & DNS SRV Config

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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