© 2006 Cisco Systems, Inc. All rights reserved.ONT v1.02-1 Describe Cisco VoIP Implementations Implementing Voice Support in an Enterprise Network. - презентация

1 © 2006 Cisco Systems, Inc. All rights reserved.ONT v Describe Cisco VoIP Implementations Implementing Voice Support in an Enterprise Network

2 © 2006 Cisco Systems, Inc. All rights reserved.ONT v Enterprise Voice Implementations

3 © 2006 Cisco Systems, Inc. All rights reserved.ONT v Enterprise Voice Implementations Components of enterprise voice networks: Gateways and gatekeepers Cisco Unified CallManager and IP phones

4 © 2006 Cisco Systems, Inc. All rights reserved.ONT v Voice Gateway Functions on a Cisco Router

5 © 2006 Cisco Systems, Inc. All rights reserved.ONT v Voice Gateway Functions on a Cisco Router Connect traditional telephony devices to VoIP Convert analog signals to digital format Encapsulate voice into IP packets Perform voice compression Provide DSP resources for conferencing and transcoding Support fallback scenarios for IP phones (Cisco SRST) Act as a call agent for IP phones (Cisco Unified CallManager Express) Provide DTMF relay and fax and modem support

6 © 2006 Cisco Systems, Inc. All rights reserved.ONT v Cisco Unified CallManager Functions

7 © 2006 Cisco Systems, Inc. All rights reserved.ONT v Cisco Unified CallManager Functions Call processing Dial plan administration Signaling and device control Phone feature administration Directory and XML services Programming interface to external applications

8 © 2006 Cisco Systems, Inc. All rights reserved.ONT v Example: Signaling and Call Processing

9 © 2006 Cisco Systems, Inc. All rights reserved.ONT v Enterprise IP Telephony Deployment Models

10 © 2006 Cisco Systems, Inc. All rights reserved.ONT v Enterprise IP Telephony Deployment Models Deployment ModelCharacteristics Single siteCisco Unified CallManager cluster at the single site Local IP phones only Multisite with centralized call processing Cisco Unified CallManager cluster only at a single site Local and remote IP phones Multisite with distributed call processing Cisco Unified CallManager clusters at multiple sites Local IP phones only Clustering over WANSingle Cisco Unified CallManager cluster, distributed over multiple sites Usually local IP phones only Round-trip delay between any pair of servers not to exceed 40 ms

11 © 2006 Cisco Systems, Inc. All rights reserved.ONT v Example: Single Site Cisco Unified CallManager servers, applications, and DSP resources are located at the same physical location. IP WAN is not used for voice. PSTN is used for all external calls. Note: Cisco Unified CallManager cluster can be connected to various places depending on the topology.

12 © 2006 Cisco Systems, Inc. All rights reserved.ONT v Example: Multisite with Centralized Call Processing Cisco Unified CallManager servers and applications are located at the central site, while DSP resources are distributed. IP WAN carries data and voice (signaling for all calls, media only for intersite calls). PSTN access is provided at all sites. CAC is used to limit the number of VoIP calls, and AAR is used if WAN bandwidth is exceeded. Cisco SRST is located at the remote branch. Note: Cisco Unified CallManager cluster can be connected to various places depending on the topology.

13 © 2006 Cisco Systems, Inc. All rights reserved.ONT v Example: Multisite with Distributed Call Processing Cisco Unified CallManager servers, applications, and DSP resources are located at each site. IP WAN carries data and voice for intersite calls only (signaling and media). PSTN access is provided at all sites; rerouting to PSTN is configured if IP WAN is down. CAC is used to limit the number of VoIP calls, and AAR is used if WAN bandwidth is exceeded. Note: Cisco Unified CallManager cluster can be connected to various places, depending on the topology.

14 © 2006 Cisco Systems, Inc. All rights reserved.ONT v Example: Clustering over WAN Cisco Unified CallManager servers of a single cluster are distributed among multiple sites, while applications and DSP resources are located at each site. Intracluster communication (such as, database synchronization) is performed over the WAN. IP WAN carries data and voice for intersite calls only (signaling and media). PSTN access is provided at all sites; rerouting to PSTN is performed if IP WAN is down. CAC is used to limit the number of VoIP calls; AAR is used if WAN bandwidth is exceeded. Note: Cisco Unified CallManager cluster can be connected to various places, depending on the topology.

15 © 2006 Cisco Systems, Inc. All rights reserved.ONT v Identifying Voice Commands in IOS Configurations

16 © 2006 Cisco Systems, Inc. All rights reserved.ONT v Identifying Voice Commands in Basic Cisco IOS VoIP Configurations

17 © 2006 Cisco Systems, Inc. All rights reserved.ONT v What is CAC?

18 © 2006 Cisco Systems, Inc. All rights reserved.ONT v What Is CAC? CAC artificially limits the number of concurrent voice calls. CAC prevents oversubscription of WAN resources caused by too much voice traffic. CAC is needed because QoS cannot solve the problem of voice call oversubscription: –QoS gives priority only to certain packet types (RTP versus data). –QoS cannot block the setup of too many voice calls. –Too much voice traffic results in delayed voice packets.

19 © 2006 Cisco Systems, Inc. All rights reserved.ONT v Example: CAC Deployment IP network (WAN) is only designed for two concurrent voice calls. If CAC is not deployed, a third call can be set up, causing poor quality for all calls. After CAC is deployed, the third call is blocked.

20 © 2006 Cisco Systems, Inc. All rights reserved.ONT v Summary Converged enterprise networks include components supporting VoIP, such as gateways, gatekeepers, Cisco Unified CallManager, and IP phones. Cisco ISRs provide voice capabilities, including gateway, call agent, and DSP functions. Cisco Unified CallManager provides call processing and signaling services and provides access to applications from IP phones. IP deployment models include single site, multisite (centralized and distributed), and clustering over WAN. Cisco IOS dial peers are used at the gateway to configure a local dial plan. CAC is a method that prevents bandwidth exhaustion caused by too many voice calls.

21 © 2006 Cisco Systems, Inc. All rights reserved.ONT v