Understanding Cisco
Unified Communications
Manager Deployment
and Redundancy
Options
Getting Started with Cisco Unified Communications Manager
© 2008 Cisco Systems, Inc. All rights reserved.
CIPT1 v6.0—1-1
Outline
 Cisco Unified Communications Manager Deployment Options
Cisco Unified Communications Manager Single-Site Deployment
 Cisco Unified Communications Manager Multisite Deployment
with Centralized Call Processing
 Cisco Unified Communications Manager Multisite Deployment
with Distributed Call Processing
 Cisco Unified Communications Manager Multisite Deployment
with Clustering Over the WAN
 Cisco Unified Communications Manager Call-Processing
Redundancy
© 2008 Cisco Systems, Inc. All rights reserved.
CIPT1 v6.0—1-2
Cisco Unified Communications Manager
Deployment Options
© 2008 Cisco Systems, Inc. All rights reserved.
CIPT1 v6.0—1-3
Cisco Unified Communications Manager
Deployment Options
Unified CM
Cluster
Applications
Unified CM
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.
CIPT1 v6.0—1-4
Cisco Unified Communications Manager
Single-Site Deployment
© 2008 Cisco Systems, Inc. All rights reserved.
CIPT1 v6.0—1-5
Single-Site Deployment
 Cisco Unified Communications
Manager servers, applications, and
DSP resources are at the same
physical location.
Cisco Unified
CM Cluster
 IP WAN (if one) is used for data
traffic only; PSTN is used for all
external calls.
 Supports approximately 30,000 IP
phones per cluster.
SIP/SCCP
PSTN
© 2008 Cisco Systems, Inc. All rights reserved.
CIPT1 v6.0—1-6
Single-Site: Design Guidelines
 Understand the current calling patterns within the enterprise.
 Use the G.711 codec; DSP resources can be allocated to other
functions, such as conferencing and MTP.
 OffNet calls should be diverted to the PSTN or sent to the legacy
PBX.
 Choose a uniform gateway for PSTN use.
 Deploy the recommended network infrastructure.
 Do not oversubscribe the Cisco Unified Communications Manager
and clustering capability.
© 2008 Cisco Systems, Inc. All rights reserved.
CIPT1 v6.0—1-7
Single-Site: Benefits
 Ease of deployment
 A common infrastructure for a converged solution
 Simplified dial plan
 No transcoding resources required, due to the use of only a single
high-bandwidth codec
© 2008 Cisco Systems, Inc. All rights reserved.
CIPT1 v6.0—1-8
Cisco Unified Communications Manager
Multisite Deployment with
Centralized Call Processing
© 2008 Cisco Systems, Inc. All rights reserved.
CIPT1 v6.0—1-9
Multisite WAN with Centralized
Call Processing
Cisco Unified
CM Cluster
 Cisco Unified Communications Manager
at central site; applications and DSP
resources centralized or distributed.
 IP WAN carries voice traffic and call
control signaling.
SIP/SCCP
 Supports approximately 30,000 IP
phones per cluster.
 Call admission control
(limit number of calls per site).
PSTN
IP
WAN
 SRST for remote branches.
 AAR used if WAN bandwidth is
exceeded.
SIP/SCCP
© 2008 Cisco Systems, Inc. All rights reserved.
SIP/SCCP
CIPT1 v6.0—1-10
Multisite WAN with Centralized Call
Processing: Design Guidelines
 Maximum of 1000 locations per Cisco Unified Communications
Manager cluster.
 Maximum of 1100 H.323 devices (gateways, MCUs, trunks, and
clients) or 1100 MGCP gateways per Cisco Unified
Communications Manager cluster.
 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.
 SRST on the branch router limits remote offices to a maximum of
720 Cisco IP phones when using a Cisco 3845 Series router.
© 2008 Cisco Systems, Inc. All rights reserved.
CIPT1 v6.0—1-11
Multisite WAN with Centralized Call
Processing: Benefits
 A common infrastructure for a converged solution.
 PSTN call cost savings when using the IP WAN for calls between
sites.
 Use of the IP WAN to bypass toll charges by routing calls through
remote site gateways, closer to the PSTN number dialed. This
practice is known as tail-end hop-off (TEHO).
 Maximum utilization of available bandwidth by allowing voice
traffic to share the IP WAN with other types of traffic.
 Use of Extension Mobility features between sites.
 Use of AAR in the case of insufficient bandwidth.
 Centralized administration.
© 2008 Cisco Systems, Inc. All rights reserved.
CIPT1 v6.0—1-12
Cisco Unified Communications Manager
Multisite Deployment with
Distributed Call Processing
© 2008 Cisco Systems, Inc. All rights reserved.
CIPT1 v6.0—1-13
Multisite WAN with Distributed
Call Processing
Cisco Unified
CM Cluster
 Cisco Unified
Communications Manager
and applications are located
at each site.
SIP/SCCP
GK
 IP WAN does not carry
intrasite call control signaling.
PSTN
 Gatekeepers can be used for
scalability.
Gatekeeper
IP
WAN
 Transparent use of the PSTN
if the IP WAN is unavailable.
SIP/SCCP
SIP/SCCP
Cisco Unified
CM Clusters
© 2008 Cisco Systems, Inc. All rights reserved.
CIPT1 v6.0—1-14
Multisite Distributed Call Processing:
Design Guidelines
 Deploy a single WAN codec
 Gatekeeper networks scale to hundreds of sites
– Implement a logical hub-and-spoke topology for the
gatekeeper
– Use gatekeeper redundancy
© 2008 Cisco Systems, Inc. All rights reserved.
CIPT1 v6.0—1-15
Multisite WAN with Distributed Call
Processing: Benefits
 PSTN call cost savings when using the IP WAN for calls between
sites.
 Use of the IP WAN to bypass toll charges by routing calls through
remote site gateways, closer to the PSTN number dialed, that is,
TEHO.
 Maximum utilization of available bandwidth by allowing voice
traffic to share the IP WAN with other types of traffic.
 No loss of functionality during IP WAN failure, because there is a
call-processing agent at each site.
© 2008 Cisco Systems, Inc. All rights reserved.
CIPT1 v6.0—1-16
Cisco Unified Communications Manager
Multisite Deployment with
Clustering Over the WAN
© 2008 Cisco Systems, Inc. All rights reserved.
CIPT1 v6.0—1-17
Clustering Over the IP WAN
Publisher / TFTP
<40-ms Round-Trip Delay
IP WAN
SIP/SCCP
QoS Enabled BW
SIP/SCCP
 Applications and Cisco Unified Communications Manager 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.
CIPT1 v6.0—1-18
Clustering Over the IP WAN:
Design Guidelines
 40-ms maximum round-trip delay between any two Cisco Unified
Communications Manager servers in the cluster
 Minimum 1.544 Mb/s and 900 kb/s for every 10,000 BHCAs within
the cluster
 Up to eight small sites using the remote failover deployment
model
 Failover across WAN supported (more bandwidth)
© 2008 Cisco Systems, Inc. All rights reserved.
CIPT1 v6.0—1-19
Clustering Over the IP WAN:
Benefits
 PSTN call cost savings when using the IP WAN for calls between
sites.
 Use of the IP WAN to bypass toll charges by routing calls through
remote site gateways, closer to the PSTN number dialed, that is,
TEHO.
 Maximum utilization of available bandwidth by allowing voice
traffic to share the IP WAN with other types of traffic.
 Failover across WAN is supported.
© 2008 Cisco Systems, Inc. All rights reserved.
CIPT1 v6.0—1-20
Cisco Unified Communications Manager
Call-Processing Redundancy
© 2008 Cisco Systems, Inc. All rights reserved.
CIPT1 v6.0—1-21
Cisco Unified Communications Manager
Redundancy
 Maximum of eight call-processing servers in a cluster.
 Redundancy is provided by Cisco Unified Communications
Manager groups.
– Prioritized list of call-processing servers (one or more).
– Multiple Cisco Unified Communications Manager groups can
exist in the same cluster.
– Each call-processing server can be assigned to more than one
Cisco Unified Communications Manager group.
– Each device has a Cisco Unified Communications Manager
group assigned determines the primary and backup server to
which it will register.
© 2008 Cisco Systems, Inc. All rights reserved.
CIPT1 v6.0—1-22
1:1 Redundancy Design
Primary
Secondary or
Backup
7500 IP phones
Cisco MCS 7845
Publisher and
TFTP Server
(Not Req.
<1000)
Primary
1 to 7500
 High availability (upgrade)
 Increased server count
 Simplified configuration
15,000 IP phones
Cisco MCS 7845
Publisher and
TFTP Server
Backups
1 to
7500
30,000 IP phones
Cisco MCS 7845
Publisher and
TFTP Server
Backups
7501 to
15,000
1 to
7500
7501 to
15,000
Backup
Backups
15001 to
22,500
22,501 to
30,000
© 2008 Cisco Systems, Inc. All rights reserved.
CIPT1 v6.0—1-23
2:1 Redundancy Design
Primary
Secondary or
Backup
7500 IP phones
Cisco MCS 7845
Publisher and
TFTP Server
(Not Req.
<1000)
Primary
1 to 7500
 Cost-efficient redundancy
 Service impacted during upgrade
15,000 IP phones
Cisco MCS 7845
Publisher and
TFTP Server
Backup
1 to
7500
30,000 IP phones
Cisco MCS 7845
Publisher and
TFTP Server
Backup
7501 to
15,000
1 to
7500
7501 to
15,000
Backup
Backup
15,001 to
22,500
22,501 to
30,000
© 2008 Cisco Systems, Inc. All rights reserved.
CIPT1 v6.0—1-24
Summary
 Supported Cisco Unified Communications Manager 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 DSP resources are
at the same physical location; all off-site calls are handled by the
PSTN.
 The multisite with centralized call-processing model has a single
Cisco Unified Communications Manager cluster; applications and
DSP resources can be centralized or distributed; the IP WAN
carries call control signaling traffic even for calls within a remote
site.
© 2008 Cisco Systems, Inc. All rights reserved.
CIPT1 v6.0—1-25
Summary (Cont.)
 The multisite with distributed call-processing model has multiple
independent sites, each with a Cisco Unified Communications
Manager cluster; the IP WAN carries traffic only for intersite calls.
 Clustering over the WAN provides centralized administration, a
unified dial plan, feature extension to all offices, and support for
more remote phones during failover. But it also places strict delay
and bandwidth requirements on the WAN.
 Clusters provide redundancy. A 1:1 redundancy design offers
thehighest availability but requires the most resources and is not
as cost-effective as 1:2 redundancy.
© 2008 Cisco Systems, Inc. All rights reserved.
CIPT1 v6.0—1-26
© 2008 Cisco Systems, Inc. All rights reserved.
CIPT1 v6.0—1-27