Interview Question for GK & CUBE

What are the benefits of using Cisco Unified Border Element ?
A:
• Multiple physical interconnects, intelligent OAM, Call Admission Control, Billing etc
• Security Demarc: FireWall, DOS protection, VPN, etc
• Signaling, Protocol & Media Interworking: H.323/SIP, transcoding, DTMF etc.
• Media QoS control and monitoring
• Interoperability: various network elements, CUCM, etc.
• Co-existence/co-operation with TDM trunking

Q: What type of Calls are supported in CUBE ?

A: CUBE supports,
• IP-to-IP Calls
• TDM Voice Calls
• Gatekeeper
• Routing

Q: How the Media is handled in CUBE ?

A: Media is handled in 2 different modes

• Media Flow-Through
• Media Flow-Around

 Q: What Platforms are supported for CUBE?

A: Cisco CUBE is an Integrated application with Cisco IOS software.
CUBE functionality is supported in Cisco 2600XM, 2691, Cisco ISR 2800, 3800 series, Cisco VXR 7200, Cisco XR 12000, AS5400XM Universal gateways and the Service Provider Gateways.

Q: Do we need Digital signal processors (DSPs) for CUBE?

A: Digital Signal Processors (DSPs) are only required for calls with dissimilar codecs

 Q: What is the licensing requirements of the CUBE?

A: If you have any existing Cisco Gateway then you can download the Cisco IOS supported version for running CUBE on your Gateway. Also you need to buy license for the no. of sessions in CUBE for different platform. Say for an example if you want to have a CUBE supporting 500 sessions , you need to buy the license for this amount.

Q: Do CUCM need special license for CUBE or it will be just a SIP trunk without license ?
A: No, there is no special license for connecting CUCM to CUBE..

Q: WE have a CUBE for a SIP connection. I know there is a license that we purchased from Cisco. Is there a command to enter on the CUBE to view the licenses?

A: The CUBE licenses are not entered into the router. As of now, they are paper licenses.
 
Q: Whether CUBE supports Voice and Data traffic simultaneously?

A: Yes. CUBE is in IOS based platform hence it can handle both Voice and Data traffic.

Q: Does CUBE have to be run on a dedicated device/router?

A: Not Necessary. It depends on the voice traffic you want to route using CUBE. For large enterprise its recommended to use standalone device for CUBE functionality. If the traffic is not high you can run other services along with the CUBE application for voice on the same platform simultaneously.

Q: Do we need DSP resources in CUBE if the SIP trunk from city (external) to the SIP trunk of CUCM will be used ? IP phones will use g711 codec. It could be e a need in DSP resources for audio conference and others supplementary services…

A: No DSP resources are required to simply connect to SIP Trunk. DSP resources are required if you plan on doing transcoding between g711 to g729 codec. For conferences if all parties are using g711 codec, then you can use the software resources in UCM to do the conferencing. If one of the parties is using g729 codec and if that needs to be conferenced, you will need to use voice gateways for hardware conferencing which will require DSPs. Digital Signal Processors (DSPs) are only required for calls with dissimilar codecs. 

Q: Will SRST work on CUBE ?
A: Yes, SRST and CUBE can be co-located on the same router.

Q: Explain the Call flow in CUBE.

A:



1.Incoming VoIP setup message from OGW to CUBE
2.This matches an inbound VoIP dial peer 1 for characteristics such as codec, VAD, DTMF method, protocol etc
3.CUBE then looks up called number in setup and matches outbound VoIP dial peer 2
4.Outgoing VoIP setup message from CUBE to TGW 
Q: How to enable the IP-IP Calls and Protocol support in CUBE ?

A: Enabling the IP-to-IP Calls
CUBE#config t
CUBE(config)# voice service voip
CUBE(conf-voi-serv)#allow-connections h323 to h323
CUBE(conf-voi-serv)#allow-connections h323 to sip
CUBE(conf-voi-serv)#allow-connections sip to h323
CUBE(conf-voi-serv)#allow-connections sip to sip

It is mandatory to have Incoming and Outgoing VoIP Dial-peers with required parameters like Protocol, Transport, Codec, CAC, QoS, etc

Q: Whether CUBE supports Universal Transcoding ?

A: Yes CUBE supports Universal Transcoding, any to any Voice codec. Example. iLBC to G.711 or iLBC to G.729
List of codecs supported

• g711alaw 64Kbps
• g711ulaw 64Kbps
• g723r53 5.3Kbps
• g723r63 6.3Kbps
• g723r63 6.3Kbps
• g729 (all variants) 8Kbps
• iLBC

Q: What is CAC ?

A: CAC is Call Admission Control. It control number of calls based on resources and bandwidth and Proactively reserve resources for good quality video calls. Also it ensure traffic adheres to QoS policies within each network. CUBE can provide six different CAC mechanisms

Q: Is CP-PWR-CUBE-4= compatible with the 7900 series phones?

A: No this power cube is for the new 8900/9900 phones, compatable with Communications Manager. The power tip is different size, won’t fit in other phones.

Q: Im trying to find a way to route inbound SIP calls, based on their source. For example:

SIPCarrier1 is coming from 1.1.1.1
SIPCarrier2 is coming from 2.2.2.2

If calls originate from SIPCarrier1, I want them to be passed to my UCM Cluster.

If call originate from SIPCarrier2, I want them to be passed to my Asterisk box.

I’ve played around with incoming called-number, trying to make it work with IP addresses, rather than phone numbers, but no luck.

Any ideas on how to enable source based routing?

A: Yes this can be achieved by Carrier based Routing. Refer this link for more details.

VoIP Gateway Trunk and Carrier Based Routing Enhancements

Q: CUBE Sizing, how many simultaneous calls/ sessions are supported on each Router model to terminate a SIP Trunk at the service provider end ?

A: Refer the given table for more details.