juniper Voice over IP Solutions

14 Oct, 2009 | Written by PassGuide Juniper Test Software | under Study Guide

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Contents
Executive Summary . . 5
Perspective 5
Legacy Voice Services 6
VoIP Functions . 9
Signaling . . 9
Database Services . . 9
Call Connect and Disconnect (Bearer Control) . . . . 9
CODEC Operations . 9
VoIP Components . . . 11
Media Gateways . . 11
Media Gateway Controllers . 11
IP Network . . . . 12
Voice Protocols and Usages . . 14
Signaling System Seven . 14
H.323 . . . . 15
Real-time Transport Protocol 17
Real-time Transport Control Protocol . . 18
Media Gateway Control Protocol . 18
Session Initiation Protocol . . 19
Signaling Transport 21
Megaco/H.248 . 22
Resource Reservation Protocol . . . 22
VoIP Service Considerations . . 23
Latency . . 23
Jitter 24
Bandwidth . . . . 25
Packet Loss . . . . 26
Reliability 27
Security . . 27
Juniper Networks VoIP Network Solutions . . 28
High-speed Interfaces . . . 28
Predictable Performance . 28
Class of Service . 29
CoS Application . . . 31
Example CoS Configuration . 32
Low Latency Design . . . . 35
Predictable and Minimal Jitter . . . . 36
Per-flow Load Balancing 36
MPLS . . . . 37
MPLS Traffic Engineering . . . 38
Constraint Based Routing . . . 39
Security Features . . 41
Reliability 42
Conclusion . . . . 44
Acronyms 44
Copyright ? 2001, Juniper Networks, Inc.
List of Figures
Figure 1: Basic Flow of Traditional PSTN and SS7 Network . . . . 8
Figure 2: Full Service VoIP Network . . 13
Figure 3: SS7 Protocol Stack . . 15
Figure 4: Example H.323 Call Process . 16
Figure 5: Upper Layers of the RTP Protocol . 17
Figure 6: MGCP Functions . . . 19
Figure 7: SIP Proxy Operation 2 0
Figure 8: SIP Redirector Server . . 21
Figure 9: Example Jitter . 25
Figure 10: Juniper Networks Class of Service 29
Figure 11: Juniper Networks Class-of-service Default . 32
Figure 12: Example Multiservice Network . . 32
Figure 13: Example Mapping of Services to Output Queues . . . 34
Figure 14: Logical View of Packet Forwarding Engine 36
Figure 15: Example Flow in an MPLS Network . 38
Figure 16: MPLS Traffic Engineering Efficiently Uses Bandwidth . . . 39
Figure 17: Full-duplex LSPs for Voice and Data Traffic 40
Figure 18: Virtual Router Redundancy Protocol . 43
Automatic Protection Switching Spanning Multiple Routers . . . 43
Copyright ? 2001, Juniper Networks, Inc.
List of Tables
Table 1: ITU Encoding Standards 10
Table 2: Example Queue Configuration 33
Figure1: Basic Flow of Traditional PSTN and SS7 Network . . . . . . . . . . . . . . . . . . . . . . . . .8
Figure2: Full Service VoIP Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Figure3: SS7 Protocol Stack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Figure4: Example H.323 Call Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Figure5: Upper Layers of the RTP Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Figure6: MGCP Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Figure7: SIP Proxy Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Figure8: SIP Redirector Server . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Figure9: Example Jitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
Figure10: Juniper Networks Class of Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
Figure11: Juniper Networks Class-of-service Default . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Figure12: Example Multiservice Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Figure13: Example Mapping of Services to Output Queues . . . . . . . . . . . . . . . . . . . . . . . .34
Figure14: Logical View of Packet Forwarding Engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36
Figure15: Example Flow in an MPLS Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
Figure16: MPLS Traffic Engineering Efficiently Uses Bandwidth . . . . . . . . . . . . . . . . . . .39
Figure17: Full-duplex LSPs for Voice and Data Traffic . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40
Figure18: Virtual Router Redundancy Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
Automatic Protection Switching Spanning Multiple Routers . . . . . . . . . . . . . . . . . . . . . . . .43
Executive Summary
Although voice over IP (VoIP) has been in existence for some years, service demands are
forcing a rapid evolution of the technology. The pace of service integration (convergence) with
new and existing networks continues to increase as VoIP products and services develop. Also,
the promise of broadband services and the integration of voice and data at all levels further the
need for VoIP applications.
Critical to success is the ability to deploy value-added and high-margin services. VoIP and
other IP-based technologies are best positioned to be the solution to realize these more
profitable services. For example, you could deploy a unified messaging system that would
voice synthesize e-mails over a phone to the subscriber.
Though VoIP is still evolving, packet-based telephony is becoming more advanced. Voice
protocols have further developed to offer a richer set of features, scalability, and
standardization than what was available only a few years ago. Today, Juniper Networks, Inc.
has solutions that enable you to deploy reliable, high-performance networks that support VoIP
services. Juniper Networks® solution translates into lower maintenance costs by using a
common, ubiquitous network to provide any number of services. Instead of deploying
discreet, separate services, each with its own physical and maintenance overhead, you can
deploy a common IP backbone to provide the needed transport.
Several factors drive VoIP application development and deployment. One obvious reason is
that of economics. Currently, increased competition amongst existing and emerging voice
service vendors has brought tremendous downward pressure in the cost of voice services in
the telecommunications market. This trend is likely to continue to accelerate the drop in voice
service prices.
Service providers, competitive local exchange carriers (CLECs), and telecommunications
providers alike are deploying VoIP.
Many existing service provider networks support mostly data (Internet) services that are
based on IP. These service providers already own and are further deploying IP
infrastructures. Service providers wanting to enter the voice services market will transport
voice traffic across these existing IP backbones. Building a parallel voice services network
based on legacy circuit-switching equipment is simply not a cost-effective option.
Many emerging CLECs are sensitive to the cost of developing voice service networks. For
many, the cost of legacy circuit-switching equipment is prohibitively high. Also the costs of
space, personnel, and operations in maintaining such networks are unacceptable. These
carriers also need a network that they can leverage to realize other data services, such as
Internet, virtual private networks (VPNs), and managed network offerings. For this group,
VoIP is an ideal solution to deploy voice services.
Major telecommunications providers are looking for ways to cut the cost of running and
upgrading existing voice networks. These carriers want to replace and augment their
existing networks with VoIP solutions for similar reasons. Another issue they face is the
state of existing tariff regulations. Major carriers can use data services to transport their
voice calls to get around traditional (regulated) pricing structures and reduce the total cost
of a phone call.
In addition to cost advantages, VoIP services have compelling technical advantages over circuit
switching. VoIP networks are based more on an open architecture than that of their
circuit-switched contemporaries. This open, standards-based architecture means that VoIP
services are more interchangeable and more modular than that of a proprietary, monolithic
voice switch. You can now select best-in-class products without being tied to one specific
vendor. Open standards also translates into the realization of new services that you can rapidly
develop and deploy rather than waiting for a particular vendor to develop a proprietary
solution. Moreover, VoIP is suitable for CTI (Computer Telephony Integration) and other
next-generation applications, which is insightful when looking to future networks that provide
enhanced services.