Introduction to Integrated Networks
Figure 8-14 illustrates a typical enterprise WAN with separate data and voice networks.
Integrating data, voice, and video in a network enables vendors to introduce new features. The unified communications network model enables distributed call routing, control, and application functions based on industry standards. Enterprises can mix and match equipment from multiple vendors and geographically deploy these systems wherever they are needed.
One means of creating an integrated network is to replace the PBXs' voice tie trunks with IP connections by connecting the PBXs to voice-enabled routers. The voice-enabled routers convert voice traffic to IP packets and direct them over IP data networks. This implementation is called VoIP. Figure 8-15 illustrates an integrated network using VoIP over an IP WAN link that carries voice and data at the same time.
Figure 8-14 Traditional Separate Voice and Data Networks
Voice Tie Trunks
Figure 8-14 Traditional Separate Voice and Data Networks
Voice Tie Trunks
Central
IP WAN Link
IP WAN Link
Central
Figure 8-15 Integrated Voice and Data Traffic in a Converged Network
Integrated IP Data & Voice WAN Link
Figure 8-15 Integrated Voice and Data Traffic in a Converged Network
Integrated IP Data & Voice WAN Link
Remote Location
Voice-enabled Router
I PBX I
Remote Location
Voice-enabled Router m
I PBX I
Central Location
PSTN
IP telephony, a superset of VoIP, is another implementation. IP phones are used, and the phones themselves convert the voice into IP packets. A dedicated network server that runs specialized call processing software replaces the PBX; in Cisco networks, this is the Cisco Unified Communications Manager. IP phones are not connected with telephone cabling. Instead, they send all signals over standard Ethernet. The "Introduction to IP Telephony" section later in this chapter provides details of this solution.
NOTE Earlier names for the Cisco Unified Communications Manager include Cisco CallManager and Cisco Unified CallManager.
Drivers for Integrating Voice and Data Networks
Although a PSTN is effective for carrying voice signals, many business drivers are forcing the need for a new type of network for the following reasons:
Data has overtaken voice as the primary traffic on many voice networks.
Companies want to reduce WAN costs by migrating to integrated networks that can efficiently carry any type of data.
The PSTN architecture was designed and built for voice and is not flexible enough to optimally carry data.
The PSTN cannot create and deploy features quickly enough.
Data, voice, and video cannot be integrated on the current PSTN structure.
IP telephony is cost-effective because of the reduced number of tie trunks and higher link efficiency, and because both voice and data networks use the same WAN infrastructure. It is much easier to manage a single network than two separate networks, because doing so requires fewer administrators, a simplified management infrastructure, and lower administrator training costs.
KEY POINT
Whether or not either caller is talking, circuit-switched (classical voice) calls require a dedicated duplex 64-kbps dedicated circuit between the two telephones. During the call, no other party can use the 64-kbps connection, and the company cannot use it for any other purpose.
Packet-switched networking uses bandwidth only when it is required. This difference is an important benefit of packet-based voice networking.
On an IP network, voice servers and application servers can be located virtually anywhere. The rationale for enterprises to maintain voice servers, as with data application servers, is diminishing over time. As voice moves to IP networks (using the public Internet for inter-enterprise traffic and private intranets for intra-enterprise traffic), service providers might host voice and application servers.
Continue reading here: Introduction to IP Telephony
Was this article helpful?