Redirect call from internet

[Anju Josua]

Dear All,

currently i am deploying telepresence on my customer.

i still confuse about design.

my topology is like this:

C60 --- VCS-C --- (DMZ) --- VCS-E --- Internet

               |

               |

          MCU

c60 and mcu is register to vcs-c

My question is about incoming call from internet. if someone want to call c60 from internet, how should they call?

My design is :

                    - they call to public ip address of vcs-e

                    - then vcs-e will redirect this call to vcs-c

                    - vcs-c will redirect this to MCU

                    - then MCU will call c60

Can this callflow works?

need advice

Thanks,

Anju Josua

[Chad Patterson]

Anju,

There are a couple ways that you could deploy this and accomplish what you are wanting to do. What you are doing will work. However, more commonly you would configure your SIP domain on both your VCS Control and your VCS Expressway. Then, you would create SRV records for that SIP domain and place them on your internal and external DNS server. Creating SRV records are detailed in this guide on page 52 (http://www.cisco.com/en/US/docs/telepresence/infrastructure/vcs/config_guide/Cisco_VCS_Basic_Configuration_Cisco_VCS_Control_with_Cisco_VCS_Expressway_Deployment_Guide_X7-0.pdf)

With these SRV records in place, a user from outside of your network could dial your C60 or MCU using the SIP URI and the call would connect.

For example, lets say the C60 is registered to the VCS control with SIP as C60@sipdomain.com and the MCU is registered to the VCS as MCU@sipdomain.com. A users external to your network could dial C60@sipdomain.com or MCU@sipdomain.com and this would connect to your MCU or C60.

This works becuase when someone dials an endpoint using your SIP domain, when they dial the endpoint will do an SRV lookup on that domain, and because you have these SRV records on an external DNS server, it will resolve to your expressway's IP address. The call will then land on your expressway, and based on your search rules, will be sent across a traversal zone to your VCS Control and then connect to your endpoint or bridge.

The guide that i mentioned above goes over a VCS Control and Expressway sample deployment. I would recommend going over this guide as it may answer any more questions that you may have!

I hope this helps.

--

Chad P.

[Anju Josua]

Chad,

thanks for your response

i already read that guide, my concern is they have to provide dns srv for public sip uri.

and every endpoint that want to call from internet should know the dns ip address.

is it possible if we just dial by ip address?

Thanks,

Anju

[Chad Patterson]

Are you trying to dial from internal to external, or external to internal?

If you are trying to accomplish external to internal, you only need to create SRV records for your SIP domain that resolve to your VCS expressway, not each individual endpoint. Once the call lands on the expressway it will handle the signaling and based on the search rules find the endpoint that was dialed.

[Jens Didriksen]

I would also create H.323 SRV records to allow for both SIP and H.323 calls.

/jens

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[Anju Josua]

Hi Jens,

i read your post on other forum.

you said that it is possible to call vcs expressway public ip address then fallback to mcu.

Is it possible if then trom mcu we set up auto attendant to direct call to other internal endpoint.

Thanks,

Anju

[Anju Josua]

Chad,

Thanks again.

I'll try your suggestion in our lab.

but, sorry for being persistent , if i want to call to ip address is it still possible? like my first design above.

my last question, can we have same sip domain for vcs-c and vcs-e?

because in the guide, it is use different sip domain.

Thanks,

Anju

[Jens Didriksen]

Examples of SRV records you should have in place, replace vcse-fqdn.com with the FQDN of your VCS-E;

_h323ls._udp SRV 1 0 1719 vcse-fqdn.com

_h323cs._tcp SRV 1 0 1720 vcse-fqdn.com

_SIP._tcp.jcu.edu.sg 43200 IN SRV 1 0 5060 vcse-fqdn.com

_SIP._udp.jcu.edu.sg 43200 IN SRV 1 0 5060 vcse-fqdn.com

_SIP._tls.jcu.edu.sg 43200 IN SRV 1 0 5061 vcse-fqdn.com

You can have the same SIP domain for both VCS-C and VCS-E.

You should also allow people to connect to you using either alias@domain or alias@VCS-E_IP_address

This is easily done by transforms and search rules on the VCS-E.

Using the fallback alias will allow people to connect to a specific alias by dialling the IP address of the VCS-E, but that's it.

If you create a static, virtual meeting room on the MCU and use that alias as your fallback alias, you can either have your end-point sitting there permanently connected (not recommended), or you will have to connect to the VMR as required.

I only use the fallback alias as a last resort to allow organisations which have absolutely no other way of connecting, to connect to us on a case by case basis.

/jens

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[Anju Josua]

Jens,

can we fallback to auto attendant in MCU (as i read in your post)?

so external user can choose which room they want to join or which endpoint they want to dial from MCU.

Thanks,

Anju

[Jens Didriksen]

Yes you can, but they can't dial the end-point(s), they can only choose an existing conference (room), and it will be up to the user to connect to the same room,

I.e. lets say you have a user called Bob, and he has his own virtual meeting room called "Bob" which is available from the auto-attendant. External user calls the VCS-E IP address and gets re-directed to the auto-attendant where he selects "Bob" from the menu and gets connected to Bobs VMR. Now it's up to Bob to connect to the same VMR to join the meeting.

It's not, in my opinion, a very elegant solution though, fallback alias is just that; fallback, and should really be used as a last resort.

Much better to use the DNS SRV records which will allow for both h.323 and SIP calls to easily connect to any of you end-points and/or desktop clients as well as the MCU.

/jens

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