Cvoice 6.0 S01 L02

Introducing Voice Gateways

Introducing Voice over IP

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-1

Understanding Gateways  A gateway connects IP communication networks to analog devices, to the PSTN, or to a PBX  Specifically, its role is the following: – Convert IP telephony packets into analog or digital signals – Connect an IP telephony network to analog or digital trunks or to individual analog stations  Two gateway signaling types: – Analog – Digital

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-2

Gateways  Support these gateway protocols: – H.323 – MGCP – SIP – SCCP  Provide advanced gateway functionality – DTMF relay – Supplementary services  Work with redundant Cisco Unified Communication Manager  Enable call survivability  Provide QSIG support.  Provide fax or modem services, or both

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-3

Deploying Gateways San Jose

Chicago

Unified Communications Manager Cluster

IP WAN

MGCP SJ-GW

Unified Communications Manager Express H.323 CHI-GW

PSTN Denver SIP DNV-GW SIP Proxy Server © 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-4

Gateway Hardware Platforms Modern enterprise models:

Cisco 2800 Series Routers

© 2008 Cisco Systems, Inc. All rights reserved.

Cisco 3800 Series Routers

Cisco Catalyst 6500 Series

CVOICE v6.0—1-5

Gateway Hardware Platforms (Cont.) Well-known and widely used older enterprise models:

Cisco 1751-V Router EOS: 03/2007 EOL: 03/2012

Cisco 1760-V Router EOS: 03/2007 EOL: 03/2012

Cisco 3600 Series Platforms EOS: 12/2004 EOL: 12/2008

© 2008 Cisco Systems, Inc. All rights reserved.

Cisco 2600XM Series Routers EOS: 03/2007 EOL: 03/2012

Cisco 3700 Series Routers EOS: 03/2007 EOL: 03/2012

CVOICE v6.0—1-6

Gateway Hardware Platforms (Cont.) Special voice gateways:

Cisco VG224 and VG248 Gateways

Cisco AS5850 Gateway Cisco AS5300 and AS5400 Series Gateways

Cisco 827-4V Router EOS: 05/2005 EOL: 05/2010 Cisco ATA 186

© 2008 Cisco Systems, Inc. All rights reserved.

Cisco 7200 Series Routers

CVOICE v6.0—1-7

Gateway Hardware Platforms (Cont.) H.323

Cisco Unified Communications Manager MGCP

SIP

SCCP

Cisco 827-4V Router

Yes

No

No

No

Cisco 2800 Series Routers

Yes

Yes

Yes

Yes

Cisco 3800 Series Routers

Yes

Yes

Yes

Yes

Cisco 1751-V and 1760-V Routers

Yes

Yes

No

Yes1

Cisco 2600XM Series Router

Yes

Yes

No

No3

Cisco 3600 Series Platforms

Yes

Yes

No

No3

Cisco 3700 Series Routers

Yes

Yes

No

No3

Cisco VG224 Gateway

Yes2

Yes2

No

Yes

Cisco VG248 Gateway

No

No

No

Yes

Cisco AS53XX and AS5400 and AS5850 Cisco Gateways

Yes

No

No

No

Communication Media Module

Yes

Yes

Yes

Yes

GW Module WS-X6608-x1 and FXS Module WS-X6624

No

Yes

No

Yes

Cisco ATA 180 Series

Yes2

Yes2

No

Yes2

Cisco 7200 Series Routers

Yes

No

No

No

Conferencing and transcoding only FXS only 3 DSP farm 1 2

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-8

IP Telephony Deployment Models Applications Cisco Unified Communications Manager Cluster

Cisco Unified Communications Manager Cluster

Applications

PSTN

IP WAN

Branch

Headquarters

Supported IP telephony deployment models:  Single-site deployment  Multisite WAN with centralized call processing  Multisite WAN with distributed call processing  Clustering over the IP WAN © 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-9

Single-Site Deployment  Cisco Unified Communications Manager servers, applications, and DSP resources at same physical location  IP WAN (if one) used for data traffic only  PSTN used for all external calls

Cisco Unified Communications Manager Cluster

 Supports approximately 30,000 IP phones per cluster PSTN ta Da nly O

SIP or SCCP

WAN

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-10

Design Guidelines  Provide a highly available, fault-tolerant infrastructure.  Understand the current calling patterns within the enterprise.  Use the G.711 codec for all endpoints; DSP resources can be allocated to other functions, such as conferencing and MTP.  Use H.323, SIP, SRST, and MGCP gateways for the PSTN.  Implement the recommended network infrastructure for high availability, connectivity options for phones, QoS mechanisms, and security.

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-11

Multisite WAN with Centralized Call Processing  Cisco Unified Communications Manager at central site; applications and DSP resources centralized or distributed  IP WAN carries voice traffic and call control signaling  Supports approximately 30,000 IP phones per cluster  Call admission control (limit number of calls per site)  SRST for remote branches

Cisco Unified Communications Manager Cluster

SIP or SCCP

PSTN

IP WAN

SRSTcapable

SRSTcapable

 AAR used if WAN bandwidth is exceeded SIP or SCCP

© 2008 Cisco Systems, Inc. All rights reserved.

SIP or SCCP

CVOICE v6.0—1-12

Design Guidelines  Minimize delay between Cisco Unified Communications Manager and remote locations to reduce voice cut-through delays.  Use the locations mechanism in Cisco Unified Communications Manager to provide call admission control into and out of remote branches.  The number of IP phones and line appearances supported in SRST mode at each remote site depends on the branch router platform.  At the remote sites, use SRST, Cisco Unified Communications Manager Express in SRST mode, SIP SRST, and MGCP gateway fallback to ensure call-processing survivability in the event of a WAN failure.  Use HSRP to provide backup gateways and gatekeepers.

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-13

Multisite WAN with Distributed Call Processing  Cisco Unified Communications Manager and applications located at each site  IP WAN carries intercluster call control signaling  Scales to SIP or SCCP hundreds of sites  Transparent use of the PSTN if the IP WAN is unavailable © 2008 Cisco Systems, Inc. All rights reserved.

Cisco Unified Call Manager Cluster

SIP or SCCP

GK

Gatekeeper

IP WAN

PSTN

SIP or SCCP

Cisco Unified Call Manager Cluster

CVOICE v6.0—1-14

Design Guidelines  Use a Cisco IOS gatekeeper to provide CAC into and out of each site.  Use HSRP gatekeeper pairs, gatekeeper clustering, and alternate gatekeeper support for resiliency.  Size the gateway and gatekeeper platforms appropriately per the SRND.  Deploy a single WAN codec.  Gatekeeper networks scale to hundreds of sites.  Provide adequate redundancy for the SIP proxies.  Ensure that the SIP proxies have the capacity for the call rate and number of calls required in the network.

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-15

Clustering over the IP WAN Publisher or TFTP server

<40 ms Round-Trip Delay

IP WAN SIP or SCCP

QoS-Enabled Bandwidth SIP or SCCP

 Applications and Cisco Unified Communications Managers of the same cluster distributed over the IP WAN  IP WAN carries intracluster server communication and signaling  Limited number of sites © 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-16

WAN Considerations  40-ms maximum RTT between any two Cisco Unified Communications Manager servers in the cluster  Use QoS to minimize jitter for the IP Precedence 3 ICCS traffic.  Design network to provide sufficient prioritized bandwidth for all ICCS traffic, especially the priority ICCS traffic.  The general rule of thumb for bandwidth is to over-provision and undersubscribe.  QoS-enabled bandwidth must be engineered into the network infrastructure.

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-17

Summary  Gateways connect IP communications networks to traditional telephony networks.  There are several types of voice gateways that can be used to meet all kinds of customer needs, from small enterprises to large service provider networks.  Supported Cisco IP telephony deployment models are single-site, multisite with centralized call processing, multisite with distributed call processing, and clustering over the IP WAN.  In the single-site deployment model, the Cisco Unified Communications Manager applications and the DSP resources are at the same physical location; the PSTN handles all external calls.

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-18

Summary (Cont.)  The multisite centralized model has a single call-processing agent, applications and DSP resources are centralized or distributed, and the IP WAN carries voice traffic and call control signaling between sites.  The multisite distributed model has multiple independent sites, each with a call-processing agent, and the IP WAN carries voice traffic but not call control signaling between sites.  Clustering over an IP WAN provides central administration, a unified dial plan, feature extension to all offices, and support for more remote phones during failover, but places strict delay and bandwidth requirements on the WAN.

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-19

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-20