This chapter provides an overview of the Cisco Voice Routing Center (VRC). The Cisco VRC is a graphical user interface (GUI) based network management tool specifically designed for managing dial plans in a Voice-over-IP (VoIP) network.
VRC Version 1.2.1 is targeted for H.323-based networks. H.323 VoIP dial plans are statically configured and managed on gateway and gatekeeper platforms. The infrastructure of a typical H.323 VoIP network includes gateways and gatekeepers.
In a typical service provider network, a number of gateways are deployed at points of presence (POPs) throughout the service provider coverage area. A gatekeeper is used to group these gateways into a logical zone of control and perform all call routing among them.
To simplify dial plan administration for these multiple gatekeeper networks, Cisco introduced the concept of a directory gatekeeper to handle call routing between local gatekeepers.
VRC is a software product that runs on Sun servers and provides a GUI client running within a web browser on PCs running the Windows operating system.
You can deploy VRC to discover the dial plan of an existing network. You can also use it to design new dial plans incorporating Cisco routers running as gateways, gatekeepers, and directory gatekeepers.
The VRC is designed to administer a VoIP network at two levels:
Administrative Domain (AD)—The highest level of administration which encompasses the entire dial plan. The AD includes all elements that participate in the VoIP call routing.
Regions—A region partitions the AD. It may contain one or more zones, gatekeeper groups, and directory gatekeepers.
VRC Version 1.2.1 uses CNS security services for user administration and authorization.
The VRC application is a tool for dial plan provisioning including:
Discovering existing dial plan configurations
Designing new dial plan configurations
Validating new dial plan configurations
Previewing new configurations
Distributing new configurations to network elements
Archiving existing dial plans with the ability of restoring an earlier configuration
The VRC application consists of a centralized dial plan management server and web-based clients distributed across an IP network. The server uses a database for storing configuration information and is responsible for all direct interaction with each managed network element. These communications occur using the Cisco IE2100 or over Telnet and HTTP protocols.
When you use VRC integrated with PTC:
VRC is launched from the PTC user interface.
Network operations are managed through the PTC Topology Manager. These include adding and deleting regions and network elements from the topology. The VRC Topology view is not accessible from the VRC client.
When you make changes to a dial plan and commit the design, any topology update, such as adding a gateway to a zone, is automatically reflected in the PTC Topology Manager.
When you change network elements through PTC, these changes are sent to VRC as events and the elements affected by the change are flagged in the VRC Baseline View and Design View.
Note A dial plan is a numbering plan for voice-enabled networks. Blocks of
numbers are assigned to physical lines or circuits and that information is propagated across the network
so that a call can be routed from one telephone to another.
Features
Cisco VRC Version 1.2.1 provides support for the following:
Arbitrary number of directory gatekeepers, but only single level hierarchy of directory gatekeepers
Gatekeeper Transaction Message Protocol (GKTMP) triggers configuration on gatekeeper
Call control security configuration
Translation rules, number expansions, and call blocking configuration
Source IP group configuration
Hairpinning calls to PSTN
Call path verification
Network and regional administrators
User administration through the CNS security module
Integration with the Packet Telephony Center (PTC)
Configuration distribution using the Cisco IE2100 or Telnet (speeds up and simplifies dial plan management for a large number of network elements)
Fifty concurrent users
Efficient dial plan administration and configuration functions for service provider VoIP networks
Architecture
The VRC is a web-based client/server architecture. The server resides on a Sun platform. It uses MySQL for its database needs and Tomcat for a servlet engine. For user management it uses the Cisco CNS Security module which has an embedded LDAP directory from DCL. The VRC code is implemented in Java and uses the Java 1.3 run-time environment. The client is a Java applet that runs within a standard Internet Explorer Version 5.0 or Version 5.5 web browser.
Note When VRC is integrated with PTC, PTC manages VRC installation, CNS security installation, and
topology operations.
VRC provides basic provisioning of dial plans and configuration of the elements in a network and with the VRC. You can also archive and restore dial plans and validate the configuration before downloading it to the elements. The VRC can be deployed in a network with an existing dial plan or it can be used to create new dial plans.
Server Architecture
The VRC server runs on a Sun SPARC platform and requires:
Sun Solaris 2.7 or 2.8 operating system
300 MB disk space
Client Architecture
The VRC client runs within a browser on a Windows PC and requires:
At least Intel Pentium III
Microsoft Windows NT4 or Windows 2000 operating system
Microsoft Internet Explorer 5.0 and 5.5 web browser
Netscape 7.0 web browser with a PC or Sun client
VRC Feature Sets
VRC uses the Cisco IOS version to determine what command line interface (CLI) it needs to generate to configure a network element. VRC applies the term "feature set" to capture the dial plan capabilities of a Cisco IOS version.
A VRC feature set is made up of a set of Cisco IOS features and a set of rules about how to apply the Cisco IOS features to the network elements to perform dial plan provisioning for the network.
The VRC Version 1.2.1 model supports the following feature sets:
dp1.0—Supports prefix routing.
dp1.1—Supports both prefix routing and carrier-sensitive routing. Devices that support dp1.1 support gateway and gatekeeper trunk and carrier-based routing enhancements.
dp1.2—Supports all dp1.0 and dp1.1 features plus hierarchical directory gatekeepers, data migration, and gateway voice applications.
The feature set for the device depends on the Cisco IOS version running on the device.
Cisco IOS Support
Cisco VRC supports the Cisco IOS versions for gateways (GWs), gatekeepers (GKs), and directory gatekeepers (DGKs) and their corresponding feature sets shown in Table 1-1.
Table 1-1 Supported Cisco IOS Software Versions and Feature Sets
Device Type
VRC Feature Set
Supported Cisco IOS Version
GW
dp1.0
Release 12.2(2)XB*
GW
dp1.0
Release 12.2(2)XA*
GW
dp1.0 and dp1.1
Release 12.2(2)XU*
GW
dp1.0
Release 12.2.7*
GW
dp1.2
Release 12.2(13)T*
GK and DGK
dp1.0
Release 12.2(2)T*
GK and DGK
dp1.0
Release 12.2(2)XA*
GK and DGK
dp1.0 and dp1.1
Release 12.2(2)XU*
GK and DGK
dp1.0 and dp1.1
Release 12.2(11)T*
GK and DGK
dp1.2
Release 12.2(13)T
*Denotes all releases of this Cisco IOS version. For example, Release 12.2(2)XB* means that the network element supports the following Cisco IOS versions: Release 12.2(2)XB1, Release 12.2(2)XB2, Release 12.2(2)XB3, Release 12.2(2)XB4, and all releases following.
Note If the Cisco IOS version of your device does not match this list, VRC assigns the default feature set of
dp1.0 to the network element.
Concurrent Operations
Most VRC operations can occur simultaneously by different users within the VRC server. However, there are certain operations that cannot run concurrently.
VRC concurrent operations constraints include:
A single user can execute only one operation at a time.
There can only be one design session open at a time for a given scope.
Design sessions that originate with the Discovery operation are opened at the Administrative Domain (AD) level.
No two operations of the same type can be executed simultaneously (exceptions: Design Export and Save Design)
Table 1-2 lists the VRC operations that cannot occur simultaneously.
Table 1-2 VRC Operation Limitations
Operation being executed
Cannot execute simultaneously
Distribution
Check network element
Distribution
Persist element configuration
Commit
Distribution within the same scope
Discovery
Import Topology
Discovery
Element activation or reactivation
Discovery
Design Export
Discovery
Commit
Discovery
Save Design
Design Preview
View generated CLI (both baseline and design views)
Import Topology
Element activation or reactivation
Check network element
Persist element configuration
View generated CLI (baseline view)
Export baseline dial plan
Because the following operations require serialized access to staging tables, they are semi-concurrent with the Commit operation:
Design Preview
View the generated CLI (both the Baseline View and Design View)
If you receive an error message that an operation cannot be executed because it cannot be initialized, wait a few moments and try again. VRC might be waiting for an operation to complete, or that operation must be in the initialized state before you can execute another operation.
If you are executing an operation for a scope that overlaps with another user, your operation request fails. If there is no scope overlap, your operation request is queued and executed when server resources become available.
Note If you are using a Cisco IE2100 device for automating the deployment and management of network
devices, your concurrent operation issues might be different.
The network element assigned to a zone to provide address resolution service to all the elements of the zone. For example, an ARA could be a gatekeeper group or OSP server.
Baseline dial plan
VRC's assessment of what is currently configured on the network.
Baseline View
The view that shows the currently configured dial plan. Use the baseline view to
CLI
Cisco IOS command-line interface.
Design View
The view that allows you to make changes to the currently configured dial plan.
Dial plan
A system that allows one telephone or Cisco IP device to connect to another telephone or Cisco IP device by using dialed digits.
Directory Gatekeeper (DGK)
An H.323 gatekeeper that provides address translation support only for other gatekeepers and not for gateways.
Directory Gatekeeper Group (DGKGrp)
A set of one or more directory gatekeepers configured for redundancy.
Discovery
The operation by which VRC queries network elements for current dial plan related configuration and updates the baseline dial plan to match.
Distribution
The process by which VRC distributes the dial plan to network elements such that their configuration matches the baseline dial plan.
Element
A router with physical counterparts that is used in a VRC dial plan. For example, gateways, gatekeepers, and directory gatekeepers.
Egress Route
An internal zone behavior for a call that is received from the IP network.
Foreign Region
A special kind of region representing adjacent, but unmanaged segment of the VoIP network
Gatekeeper (GK)
An H.323 entity on a LAN that provides address translation and control access for H.323 terminals and gateways.
Gatekeeper Group (GKGrp)
A set of one or more gatekeepers configured for redundancy.
Gateway
A network access server (NAS) that acts as an interface between a circuit-switched Public Switched Telephone Network (PSTN) and a packet H.323 VoIP network.
Hierarchical DGKs
An H.323 configuration where multiple levels of GKs and DGKs are in the LRQ forwarding path.
Ingress Route
An internal zone behavior on the ingress side of the call, when the call is received from the PSTN.
LRQ Transit Region
A special type of managed region that contains only a single DGKGrp. LRQ transit regions are used to create a DGK hieracrchy.
Managed Zone
A subset of a managed region, logically corresponding to an H.323 zone.
Managed Region
A logical subset of zones that partitions the VRC managed VoIP netowrk.
Outgoing Region Connection
The assignment of another region as a potential destination for an outbound LRQs.
PTC
Packet Telephony Center
Routes
Calls that leave or enter a zone in a VoIP network.
Route Scope
A collection of call originating or terminating resources within a managed zone. Route scope are used to determine the scope of ingress or egress routes.
