How does Redundant CUPS server Work in Failover Mode ?

[azeemo157]

Hi All

I have to install a Redundant CUPS server at one of my sites. I know you have to add the secondary server in the Server tab in CUPS Administration page. But for CUCM and CUPC how will it know that there is a secondary CUPS server ? Also in the SIP Trunk we can mention noly 1 IP address. So how ill the Failover Mechanism work. Any help will be much appreciated.

[htluo]

When CUPC logs in, it retrieve the configuration from CUPS via SOAP protocol.  Within the configuration, there's a list of CUPS servers and the "home" server.

CUPC will try to use the "home" server for SIP/XMPP.  If that failed, CUPC will use the other server.

If you want redundancy for SIP trunk, you need to use SRV record from CUCM configuration.  SRV is a type of DNS record that points to actual hosts (A records).  CUCM will try the first A record on the list.  If that failed, it'll try the 2nd one.  So on so forth.

Michael

http://htluo.blogspot.com

[azeemo157]

Thank you For your reply

I tried this. i created two Host A records with the Same name and different IP Address, the from my PC i did an nslookup to this hostname and it showed me hits to both IP's. This means both the IP's will get hits. So it will be in an active-active state. I guess the Best workaround is to use Windows NLB or Cisco ACE. If the same can be done through DNS please do advice as my knowldge with Microsoft is limited. Thanks for your Reply once again

[htluo]

You should have two A records with different name and different IP address.  For example:

cup01.mydomain.com 192.168.1.100

cup02.mydomain.com 192.168.1.200

Then you may point your SRV record to the two A records.  In the SRV record, you also specify service type, port number, priority, etc.

For more details, please see: http://en.wikipedia.org/wiki/SRV_record

Thanks!

Michael

[Zaid Ahmaad Ibrahim Al-Taiar]

Where should i create the SRV record as well as the HOST A records ? Is it on a windows based DNS Server or a Linux Based DNS Server ? If On a Linux based Server could you please explain how it is done ? As for CUCM we will just have to enter a hostname in the SIP Address tab rite ? So this hostname is the one that we mention in the SRV records ? I would appreciate if you could explain to me how this will work.

Thank you very much for the help Extended.

[htluo]

You create those records on a DNS server.  The DNS server could be Windows, Linux, or any appliances.  If you don't know where it is, you may check with your network administrator.

How to create DNS records is specific to the DNS server.  Please refer to Windows or Linux administration guide.  Or you may ask the network administrator to do it for you.

On CUCM SIP trunk configuration, there's a checkbox indicate the name is a SRV record.  You check that checkbox and enter the SRV name into the "destination address" field.

Michael

http://htluo.blogspot.com

[azeemo157]

Hi

I created the SRV records. In the Presence Administration>system>service parameters. in the UC Sip Proxy i edited the SRV cluster name as well as in the address resolution i made it SRV.

Now i am confused in the SIP trunk in Call manager what should be given in the destination address ? I have already checked marked use SRV o nthe trunk.

also for the CUPC client what should be mentioned in the Login server field.

[htluo]

You are confusing three different things into one. 

1) CUPS > Service Parameter > SIP Proxy Domain.

This is to define the SIP Proxy Domain of the CUPS.  "Proxy Domain" is a SIP concept.  It defines the domain that the system handles.  For example, your Proxy Domain is "mycompany.com".  If the server received a SIP message with the "To:" field set to "johndoe@mycompany.com", it know this message should be handled locally.  However, if it received a SIP message with "To:" field set to "johndoe@acme.com", it knows this message should be forwarded/redirected somewhere else because the domain is different.

SIP Proxy Domain is NOT a DNS concept.  And it has NO redundancy concern.

For difference between SIP Proxy Domain and DNS domain, please see: http://htluo.blogspot.com/2009/01/sip-domain-and-dns-domain.html

2) CUCM > Device > Trunk > SIP Trunk > Destination Address

This is for data transport.  SRV record is a DNS concept.  The goal is to add another layer on of of A record.  So we could get a DNS name resolved to multiple host addresses in one DNS query.

3) CUPC log on server address

This is for CUPC log on.  Please note CUPC log on process is NOT a SIP process.  CUPC log on does NOT support SRV record.  CUPC log on redundancy is achieved automatically after the intial logon.  It retrieves the server list from CUPS server via SOAP and stores it locally on the client PC.

Michael

http://htluo.blogspot.com