Cisco Unified Border Element Fundamentals and Basic Setup
Cisco Unified Border Element Fundamentals and Basic Setup
Last Updated: May 10, 2012
This Cisco Unified Border Element is a special Cisco IOS software image that provides a network-to-network interface point for billing, security, call admission control, quality of service, and signaling interworking. This chapter describes basic gateway functionality, software images, topology, and summarizes supported features.
Cisco Product Authorization Key (PAK)--A Product Authorization Key (PAK) is required to configure some of the features described in this guide. Before you start the configuration process, please register your products and activate your PAK at the following URL http://www.cisco.com/go/license.
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Getting Started with Important Concepts
Prerequisites for Cisco Unified Border Element
Cisco Unified Border Element Hardware
Cisco Unified Border Element Software
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS and Catalyst OS software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn . An account on Cisco.com is not required.
Restrictions for Cisco Unified Border Element
Information About Cisco Unified Border Element
When you configure SIP on a router, the ports on all its interfaces are open by default. This makes the router vulnerable to malicious attackers who can execute toll fraud across the gateway if the router has a public IP address and a public switched telephone network (PSTN) connection. To eliminate the threat, you should bind an interface to private IP address that is not accessible by untrusted hosts. In addition, you should protect any public or untrusted interface by configuring a firewall or an access control list (ACL) to prevent unwanted traffic from traversing the router.A Cisco Unified Border Element facilitates connectivity between independent VoIP networks by enabling SIP and H.323 VoIP and videoconferencing calls from one IP network to another. This gateway performs most of the same functions of a PSTN-to-IP gateway, but typically joins two IP call legs, rather than a PSTN and an IP call leg. Media packets can flow either through the gateway (thus hiding the networks from each other) or around the border element, if so configured.
Cisco Unified Border Element is a special Cisco IOS software image that runs on the Cisco AS1000 platform. It provides a network-to-network interface point for billing, security, call admission control, quality of service, and signaling interworking.
Cisco UBE is designed to meet the interconnection needs of Internet telephony service providers (ITSPs) and of enterprises. One set of images provides basic interconnection and a second set provides interconnection through an Open Settlement Protocol (OSP) provider, enabling ITSPs to gain the benefits of the Cisco Unified Border Element while making use of the routing, billing, and settlement capabilities offered by OSP-based clearinghouses.
Feature benefits include the following:
Gateways are responsible for the following tasks.
Cisco Unified Border Element Network Topology
In the current VoIP market, ITSPs who provide wholesale VoIP services use their own IP-to-TDM gateways to exchange calls with the PSTN. Problems occur when a wholesaler receives a call from an originating ITSP and decides to terminate the call to another ITSP. Because it does not own the PSTN gateways, the wholesaler does not receive call setup or release information and therefore cannot bill for the call. Wholesalers are forced either to forbid these connections, thereby foregoing a potential revenue source, or to set up the call through a combination of back-to-back IP-to-TDM gateways. This solution results in reduced quality due to double media coding and decoding, and it wastes TDM port resources.
Cisco Unified Border Element allows the wholesaler to terminate the call from the originating ITSP and then reoriginate it, thereby providing a point at which accurate call detail records (CDRs) can be collected for billing.
The superior interconnect capability provided by the Cisco Unified Border Element enables service providers to conceal their internal network and business relationships while improving call admission control, flexible routing, and protocol interworking capabilities.
The Cisco Unified Border Element includes the following changes to gateways and gatekeepers to allow Cisco UBE call legs:
Via-zones are usually located on the edge of an ITSP network and are like a VoIP transfer point, or tandem zone, where traffic passes through on the way to the remote zone destination. Gateways in this zone terminate requested calls and reoriginate traffic to its final destination. Via-zone gatekeepers operate as usual for applications that are not Cisco UBE gatekeepers in via-zones support resource management (for example, gateway selection and load balancing) using the Capacities field in the H.323 Version 4 RAS messages.
The figure below shows a simple topology example of the Cisco Unified Border Element using via-zone gatekeepers.
The gatekeeper in Domain A and the gatekeeper in Domain B are connected to the via-zone gatekeeper. GK408 and the via-zone gatekeeper exchange Registration, Admission, and Status (RAS) messages for the originating side. Then the connection is made between the originating gateway and the Cisco Unified Border Element. The via-zone gatekeeper exchanges RAS messages with GK919 for the terminating side. If the call is accepted, the Cisco Unified Border Element completes the connection from GW408 to GW919, and the media flows through the Cisco Unified Border Element.
In a basic call scenario, on receiving a location request (LRQ) message from the originating gatekeeper (GK408), the via-zone-enabled gatekeeper (GKVIA) processes the message and determines that the call should be set up using the Cisco Unified Border Element. After the originating gateway receives its admission confirmation (ACF) message, it sets up the call.
With the Cisco Unified Border Element feature, instead of the originating gateway signaling the terminating gateway directly, the Cisco Unified Border Element controls the call set-up both the signaling and media channel. The Cisco Unified Border Element is terminating the signaling and media channels, but the information associated with the media is propagated through to the opposite call leg. This process allows the endpoints to determine what media channel capabilities to use for the call. When the call is established, the audio stream flows through the Cisco Unified Border Element, meaning that the gateway terminates the audio channel on one call leg and then reorginates it to the other leg.
The following scenario illustrates a basic call from the originating gateway to the terminating gateway, using the Cisco Unified Border Element and gatekeepers.
All other messages (for example, Proceeding, Alerting, and Connect) are created as two legs between GW408, and GW919, with the Cisco Unified Border Element acting as an intermediate gateway.
Lawful Intercept Support
Lawful Intercept (LI) is the term used to describe the process by which law enforcement agencies conduct electronic surveillance of circuit communications as authorized by judicial or administrative order. Cisco Service Independent Intercept (SII) supports voice and data intercept and intercept requests are initiated by MD using SNMPv3.
Basic SIP-to-SIP Set-up and Functionality Features
Basic Dial Plan Management
Configuring Call Rate Monitoring
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