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Bandwidth Optimization

Solutions: BuildingCost-Effective Backup

Protection Networks

Application Note


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Executive Summary

Ensuring service and revenue generation in the event of technical failures or external events presents challenges for

telecom carriers and service providers building critical failure protection network solutions. Critical failure protection

backup minimizes the impact of these failures or events and can be implemented with various levels of redundancy,

ranging from internal redundancy on a per-equipment basis up to fully redundant networks, including geographic

redundancy network architectures. Typically, the costs involved in implementing redundant systems as effective

backup solutions duplicates the costly investment demanded for just a single transmission network.

This application note explains how the Dialogic

I-Gate

4000 PRO Media Gateway and Dialogic

I-Gate

4000 EDGEMedia Gateway can enable carriers and service providers to build cost-effective and highly reliable backup solutions

for their transmission networks, allowing signicant CAPEX and OPEX savings and short implementation cycles.

Two example solutions are described for using these Dialogic I-Gate 4000 Media Gateways in backup network

solutions, both allowing telecom carriers and service providers to minimize expenses and/or better utilize the invested

(deployed) transmission infrastructure by expanding the trafc-carrying capability and improving the overall Quality of

Service performance.

Application NoteBandwidth Optimization Solutions: BuildingCost-Effective Backup Protection Networks


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Application NoteBandwidth Optimization Solutions: BuildingCost-Effective Backup Protection Networks

Table of ContentsIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Backup Network Protection Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Backup Network Protection Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Backup Network Protection Reliability and Cost Challenges . . . . . . . . . . . . . . . . . . . . . . . 6

Building Cost-Effective Backup Protection Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

The Standalone Static Trunking Operating Mode Characteristics . . . . . . . . . . . . . . . 7

Solution 1 I-Gate 4000 PRO Gateway Backup Network Solution . . . . . . . . . . . . . . 10

Solution 2 Backup Network Solution with Load-Sharing Mode . . . . . . . . . . . . . . . 15

1


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Bandwidth Optimization Solutions: BuildingCost-Effective Backup Protection Networks

Application Note

2

Introduction

Telecom carriers and service providers worldwide have been challenged to build critical failure protection network solutions to

ensure their services (and resulting revenue) continue in the event that one or more critical segments of their telecom infrastructure

go out of service due to technical failure or an external agent (for example, accident, earthquake, terror attack, and so on).

In order to minimize the impact should these risks actually occur, different levels of redundancy can be implemented, ranging

from internal redundancy on a per-equipment basis up to fully redundant networks including geographically redundancy network

architectures.

Specically, for the transmission networks that carry the interswitch trafc between 2G mobile (for example, Mobile Switching

Center [MSC]) and/or PSTN switches (for example, Class 4), despite the technical and operational benets of highly resilientnetwork architectures (for example, SDH/SONET dual-ring), maximum overall reliability calls for separating the two different

transmission networks. However, building an ef fective backup network solution typically duplicates the investment demanded for a

single transmission network alone, which can be high considering the multiple cost components of a network deployment project.

Dialogic I-Gate 4000 PRO Media Gateway and Dialogic I-Gate 4000 EDGE Media Gateway (collectively, Dialogic I-Gate

4000 Media Gateways) provide an unparalleled opportunity for operators to build a fully featured backup transmission network

and to achieve the high overall reliability target for their mobile and/or wireline interswitch trafc at greatly reduced CAPEX, while

providing rapid infrastructure rollout, minimizing OPEX, and maintaining high-quality services.

This application note describes characteristics and benets to the operator of backup network solutions that use I-Gate 4000 Media

Gateways. It also introduces backup transmission networks concepts, including typical topologies and operating characteristics,

and presents two examples of backup transmission network solutions that can be built using I-Gate 4000 Media Gateways.

Backup Network Protection Overview

Mobile 2G switches (for example, MSC) and wireline PSTN switches (for example, Class 4) are interconnected with other mobile

and/or PSTN switches through long-distance international or domestic links (interswitch trunks) implemented over one or more

transmission networks.

Figure 1 shows a simplied example of a transmission network providing interconnection to MSC and/or PSTN switches. This

gure shows the TDM trunks through which the switches are connected to the transmission network that carries the interswitch

trafc (depicted by solid line arrows) between them.

Figure 1. Interswitch Transmission Network

MSC/PSTN

Switch 1

MSC/PSTN

Switch 2

MSC/PSTN

Switch 3

MSC/PSTN

Switch 4

MSC/PSTN

Switch 5

Transmission

Network

Trunks Trunks Trunks Trunks Trunks

Interswitch Traffic


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Application Note

3

From a network planning, deployment, and operations perspective, as well in view of CAPEX and OPEX considerations, it is

important to keep in mind that although the transmission network is depicted as a single schematic entity (a cloud), the physical

implementation of typical transmission links between any pair of switches can include one or several network segments, where

each network segment can use a different transport technology (for example, ber, microwave radio, satellite) and different

transmission link hierarchical levels (for example, E1, T1, DS3, SDH/SONET).

The ownership of the network segments is also an important factor to consider. The various network segments can be owned

by the same operator (which may or may not be the operator that owns one or more of the switches) or by different operators or

carriers (for example, leased lines).

It should be noted that when the end-to-end transmission link between a pair of switches includes several transmission network

segments, the overall reliability (that is, the service continuity characteristics) of the complete transmission link between the

switches will be determined by the least reliable network segment that is between them.

Under normal (that is, no failure) transmission network conditions, the depicted network carries the trafc between the switches.

However, in case of a failure of the interswitch transmission network, part or all of the trafc-carrying capability of the network

could be affected, resulting in trafc between two or more switches not being transported.

Backup Network Protection Models

To overcome trafc interruptions when trafc-affecting failure conditions occur in the interswitch transmission network, the

operator can follow different solution approaches:

Use alternative routing on the mobile switches or PSTN switches, and route the trafc through other trunks and switches

(not shown in Figure 1). Typically, due to limited transmission and switching resources, a Figure 1 solution can handle a

small percentage of the total required trafc load demand.

Use a two-network switch interconnection solution by building a redundant (that is, backup) transmission network in

addition to the primary transmission network and connecting the switches simultaneously to both networks. Such a solution

can be implemented by interconnecting the switches either through a dual-ring SDH/SONET network or through a pair of

separate networks (for example, primary and backup transmission networks). Figure 2 provides an example of a simplied

diagram of this type of solution architecture, where each switch is connected to the primary network through primary trunk

links and to the backup network through separate backup trunk links.

When using a two-network protection solution, the trafc between any pair of switches is normally carried over the primary

network. In case of a failure on the primary network, this trafc is carried over the backup network.

Operators can build a backup transmission network using their own transmission infrastructure, or they can lease one from one

or more other operators.


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Application Note

4

Figure 2. Primary and Backup Transmission Networks

Figure 3, Figure 4, and Figure 5 are examples depicting the trafc handling ows for different primary network operating conditions.

Figure 3 is an example of the interswitch trafc ow (depicted by solid line arrows) under a normal primary network operating

condition. When the primary transmission network has no trafc-affecting failure, the trafc is fully transported through it. In the

event of a failure that affects the trafc-carrying capability of the primary transmission network, the trafc between some or all of

the switches is transported through the backup network, as shown in Figure 4 and Figure 5.

Figure 4 is an example of the trafc ow for a case in which all the primary network links are affected, and accordingly all the trafc

is transported through the backup network.

Figure 5 is an example of the trafc ow where only some interswitch links on the primary network are affected (between switches

2 and 4) and their trafc is carried over the backup network. The interswitch trafc between other switches is not affected and is

transported over the primary network (between switches 1, 3, and 5).

For illustrative purposes, Figure 5 shows simplied examples only. Not shown is the trafc between switches 1, 3, and 5 and

switches 2 and 4; that trafc can be carried either through the primary network or through the backup network, depending on the

location of the failure(s) in the primary network.

MSC/PSTN

Switch 1

MSC/PSTN

Switch 2

MSC/PSTN

Switch 3

MSC/PSTN

Switch 4

MSC/PSTN

Switch 5

Primary

Transmission Network

(e.g. Network #1 or

SDH Ring 1)

Backup


(e.g. Network #2 or

SDH Ring 2)Backup

Trunk Links

Primary

Trunk Links


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Application Note

5

Figure 3. Trafc Handling or Fully Available Primary Network

Figure 4. Trafc Handling or Fully Unavailable Primary Network

MSC/PSTN

Switch 1

MSC/PSTN

Switch 2

MSC/PSTN

Switch 3

MSC/PSTN

Switch 4

MSC/PSTN

Switch 5

Primary

Transmission Network(e.g. Network #1 or

SDH Ring 1)

Backup


SDH Ring 2) Backup

Trunk Links

Primary

Trunk Links

Interswitch Traffic

MSC/PSTN

Switch 1

MSC/PSTN

Switch 2

MSC/PSTN

Switch 3

MSC/PSTN

Switch 4

MSC/PSTN

Switch 5

Primary


SDH Ring 1)

Backup


SDH Ring 2)Backup

Trunk Links

Primary

Trunk Links

Interswitch Traffic


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Application Note

6

Figure 5. Trafc Handling or Partially Available Primary Network

Backup Network Protection Reliability and Cost Challenges

For maximum overall reliability, there can be layout separation between the primary transmission network and the backup network,

whether the transmission network protection architecture is dual-ring SDH/SONET, or separate primary and backup networks.

Building a backup network typically duplicates the costly investment for a primary network deployment project alone (for example,

cable duct laying, cable construction, right of passage, radio links and associated repeaters, coordination with and authorization

from government ofces and service companies).

Fortunately, telecom operators and service providers requiring backup protection transmission networks can position themselves

to benet from bandwidth optimization systems that use I-Gate 4000 PRO Gateway and/or I-Gate 4000 EDGE Gateway products.

By using these I-Gate 4000 Media Gateways to build fully featured and cost-effective backup transmission network solutions, they

can stand to achieve the high overall reliability target for their interswitch trafc networks at a greatly reduced CAPEX budget, while

providing rapid infrastructure rollout, minimizing OPEX, and maintaining high-quality services.

The following sections describe examples of solutions that incorporate I-Gate 4000 Media Gateways.

Building Cost-Effective Backup Protection Networks

The main components of the proposed backup protection network solution examples are a Dialogic I-Gate 4000 PRO Gateway

and an I-Gate 4000 EDGE Gateway operated in static trunking mode. In a static trunking application, I-Gate 4000 Media Gateways

are deployed at both ends of the long-distance links that interconnect 2G mobile (for example, MSC) and/or PSTN (for example,

Class 4) switches, performing bandwidth optimization algorithms on the telephony and signaling interswitch trafc.

The I-Gate 4000 Media Gateways bandwidth optimization algorithms allow a signicant reduction in the required bandwidth

(typically 88% to 94% bandwidth savings after the solution is deployed) while also providing high voice quality and highly reliable

switch signaling (for example, SS7, PRI, CAS) performance.

MSC/PSTN

Switch 1

MSC/PSTN

Switch 2

MSC/PSTN

Switch 3

MSC/PSTN

Switch 4

MSC/PSTN

Switch 5

Primary


SDH Ring 1)

Backup


(e.g. Network #2 or

SDH Ring 2)

Interswitch Traffic

Backup

Trunk Links

Primary

Trunk Links


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Application Note

7

The following sections briey describe I-Gate 4000 Media Gateways standalone static trunking operation mode; and how I-Gate

4000 Media Gateways operating in static trunking mode can be used when it is desired to build cost-effective and highly reliable

backup network protection solutions.

The Standalone Static Trunking Operating Mode Characteristics

The following two I-Gate 4000 Media Gateways products are discussed in this application note:

I-Gate 4000 PRO Media Gateway (I-Gate 4000 PRO Gateway) For medium and heavy trafc applications (several

thousands of simultaneous calls) and support for E1, T1, DS3, STM1, and OC-3 TDM network interfaces

I-Gate 4000 EDGE Media Gateway (I-Gate 4000 EDGE Gateway) For lower-volume trafc applications of up to 496

simultaneous calls and support for E1 and T1 TDM network interfaces

These I-Gate 4000 Media Gateways use the same core technologies and provide the same trafc handling, bandwidth savings,

and service quality performance, including:

Signicant bandwidth savings (typically 88% to 94%) for short Return on Investment (ROI) period

High-quality voice services and successful fax and modem calls handling for end-user satisfaction

Reliable detection and transport of H.324 video calls

Bandwidth-efcient and robust signaling transport (SS7, PRI, CAS) for maximizing call completion rate

Reliable echo cancellation for all supported calls

Smart end-to-end compression algorithm for providing high voice quality in call paths including two or more bandwidth

optimization hop segments

Figure 6 is an example of a simple static trunking of a two site application, including a pair of I-Gate 4000 PRO Gateways carrying

the long-distance trafc between two MSC or PSTN switches.

This example conguration has the following characteristics:

The I-Gate 4000 PRO Gateways are connected to the MSC or PSTN switches through standard TDM trunk links (for

example, E1, T1, DS3, STM1, or OC-3). The TDM trunks carry the standard (that is, PCM format) telephony signals (for

example, voice, fax, and modem) and signaling (for example, SS7, PRI, CAS). The solid line arrows depict this standard

interswitch trafc.

The interconnection between the I-Gate 4000 PRO Gateways (called the bearer link) is typically implemented over standard

TDM transmission links. Bearer links can be optionally implemented over IP networks.

At the I-Gate 4000 PRO Gateway, the standard interswitch trafc received from the switches over the TDM trunk links (solidline arrows) is processed using high quality and highly reliable bandwidth optimization mechanisms, and the optimized

interswitch trafc payloads (dashed line arrows) are carried over the bearer link (using a long-distance transmission network)

to the I-Gate 4000 PRO Gateways at the distant site, where the received payloads are processed back to the original PCM

format and transmitted to the associated MSC or PSTN switch.

The I-Gate 4000 Media Gateways bandwidth optimization algorithms allow for a signicant reduction in the required bandwidth

(typically 88% to 94% bandwidth savings) while also providing high voice quality and highly reliable signaling (for example, SS7,

PRI, CAS) performance.

It should be stressed that in a static trunking application, the I-Gate 4000 Media Gateways execute the trafc handling tasks

automatically as standalone terminals, without requiring additional external call control or signaling systems.


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Application Note

8

Figure 6. Two-Site Static Trunking Application

In addition to what is shown in the simple two-site application example of Figure 6, an I-Gate 4000 Gateway can simultaneously

support static trunking operation with multiple I-Gate 4000 Gateways installed at different remote sites. Figure 7 is an example

where each I-Gate 4000 PRO Gateway supports static trunk operation with multiple distant I-Gate 4000 PRO Gateway terminals.

The Figure 7 solution example has the following characteristics:

Each I-Gate 4000 PRO Gateway independently processes and optimizes the trafc carried between its unit and each one of

the remote I-Gate 4000 PRO Gateways, providing a signicant bandwidth savings (typically between 88% and 94%) while

also providing high quality and reliable trafc transport performance.

Each I-Gate 4000 PRO Gateway independently supports the bearer link(s) between its unit and one or more of the remote

I-Gate 4000 PRO Gateways.

Figure 7. Multiple Site Static Trunking Application

MSC/PSTN

Switch

Dialogic I-Gate 4000PRO Media Gateway MSC/PSTN

Switch


TDM

Trunks

Optimized Traffic

(Bearer Link)

TDM

Trunks

Original Interswitch Traffic Optimized Interswitch Traffic

I-Gate 4000 PRO

mized Traffic

earer Link)

88% - 94%

Bandwidth Savings

MSC/PSTN

Switch

Dialogic I-Gate 4000

PRO Media Gateway

TDMTrunks TDM

Trunks

Original Interswitch Traffic

Optimized Interswitch Traffic

I-Gate 4000 PROI-Gate 4000 PRO

88% - 94%

Bandwidth Savings

MSC/PSTN

Switch

MSC/PSTN

Switch

TDMTrunks TDM

Trunks

I-Gate 4000 PRO

MSC/PSTN

Switch

MSC/PSTN

Switch

TDMTrunks

TDMTrunks

I-Gate

4000 PRO

I-Gate

4000 PRO

MSC/PSTN

SwitchTransmission Network


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Application Note

9

It should be noted that although Figure 6 and Figure 7 show I-Gate 4000 PRO Gateway terminals only, an actual application could

include a combination of I-Gate 4000 PRO Gateway and I-Gate 4000 EDGE Gateway terminals, or I-Gate 4000 EDGE terminals

only. For example, an I-Gate 4000 PRO Gateway can be deployed at sites requiring the support of a large number of MSC/PSTN

trunks, and an I-Gate 4000 EDGE Gateway can be deployed at sites requiring support for a small number of MSC/PSTN trunks.

An example of a solution using only I-Gate 4000 EDGE Gateway terminals would be one in which multiple low-trafc rural or island

switch sites are interconnected through thin-route satellite links.

I-Gate 4000 Media Gateways can be connected to transmission networks using supported TDM interfaces and network topologies.

Figure 8 is an example of multiple I-Gate 4000 PRO Gateway terminals and mobile and/or PSTN switches interconnected through

SDH transmission links.

In the Figure 8 example, the trunk links carrying the trafc between the MSC and/or PSTN switches and the I-Gate 4000 PRO

Gateway terminals, as well as the bearer links carrying the optimized trafc between the I-Gate 4000 PRO Gateway terminals, are

implemented on the SDH transmission network.

Figure 8. SDH-based Network Topology

In the Figure 8 conguration, the I-Gate 4000 PRO Gateway provides operators with the exibility to dene the allocation of trunk

and bearer links to best match their planning and budget targets. For example, one operator can allocate different STM1 interfaces

and links for trunk and bearer trafc, whereas another can allocate some E1 spans within an STM1 interface and link to carry trunk

trafc, and allocate other E1 spans within the same STM1 interface and link to carry bearer trafc.

MSC/PSTN

Switch

Dialogic I-Gate 4000

PRO Media Gateway

MSC/PSTN

Switch

I-Gate 4000 PRO

SDH Transmission Network

ADM

I-Gate 4000 PRO

I-Gate 4000 PRO

ADM

ADM ADM

MSC/PSTN

Switch

MSC/PSTN

Switch

MSC/PSTN

Switch

MSC/PSTN

Switch

I-Gate

4000 PRO

I-Gate

4000 PRO

ADMADM


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Application Note

10

Solution 1 I-Gate 4000 PRO Gateway Backup Network Solution

Figure 9 is an example of a backup network solution in which I-Gate 4000 PRO Gateways are connected between the MSC or

PSTN switches and the backup transmission network that provides operational protection to the primary transmission network.

The I-Gate 4000 PRO Gateways are congured to operate in Static Trunking mode, as described in The Standalone Static

Trunking Operating Mode Characteristics section of this application note.

In this network protection solution, the trafc between a pair of switches is normally carried over the primary network. In case of

a failure in the primary network, the trafc to be carried through the failed links is routed by the switches to the associated I-Gate

4000 PRO Gateway terminals, and this trafc is optimized by these terminals and transported over the backup network.

The following sections describe three different examples of primary transmission network operating conditions for trafc handlingows for a Solution 1 example.

Figure 9. Solution 1 Backup Transmission Network Architecture

MSC/PSTN

Switch 1

MSC/PSTN

Switch 2

I-Gate

4000 PRO

MSC/PSTN

Switch 4

MSC/PSTN

Switch 5

I-Gate

4000 PRO

Dialogic I-Gate

4000 PRO

Media Gateway

I-Gate

4000 PRO

I-Gate

4000 PRO

MSC/PSTN

Switch 3

Primary


SDH Ring 1)

Backup


SDH Ring 2)


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Application Note

11

Solution 1 Trafc Flow or Fully Available Primary Network

When the primary transmission network has no trafc-affecting failure, the trafc between the switches is fully transported through

the transmission network. Figure 10 is an example of the interswitch trafc ow (solid line arrows) under a normal primary network

operating condition.

Figure 10. Solution 1 Trafc Flow when Primary Network is Fully Available

MSC/PSTN

Switch 1

MSC/PSTN

Switch 2

I-Gate

4000 PRO

MSC/PSTN

Switch 4

MSC/PSTN

Switch 5

I-Gate

4000 PRO

Dialogic I-Gate

4000 PRO

Media GatewayI-Gate

4000 PROI-Gate

4000 PRO

MSC/PSTN

Switch 3

Original Interswitch Traffic

Primary


SDH Ring 1)

Backup


(e.g. Network #2 orSDH Ring 2)


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Application Note

12

Solution 1 Trafc Flow or Fully Unavailable Primary Network

In the case of a critical failure in the primary transmission network that makes it totally unavailable, in the Figure 10 example the

trafc is automatically routed by the switches through the I-Gate 4000 PRO Gateway terminals, which optimize and transmit the

optimized trafc over the backup network.

Figure 11 is an example of the interswitch trafc ow transmitted from the switches to the I-Gate 4000 PRO Gateways (solid line

arrows) and the optimized trafc ow transmitted between the I-Gate 4000 PRO Gateways over the backup network (dashed line

arrows).

Figure 11. Solution 1 Trafc Flow when Primary Network is Fully Unavailable

The highly reliable compression mechanisms of the I-Gate 4000 PRO Gateway terminals provide that the telephony signals

(for example, voice, fax, modem) and signaling (for example, SS7, PRI, CAS) are carried over the backup network with minimal

bandwidth requirements (88% to 94% bandwidth savings), thus allowing substantial savings on equipment and operations, together

with the high-quality service necessary to avoid negatively impacting a companys competitiveness and revenue generation.

In this example, it is assumed that all the primary network links are unavailable and accordingly that all the trafc is transported

through the backup network.

MSC/PSTN

Switch 1

MSC/PSTN

Switch 2

I-Gate

4000 PRO

MSC/PSTN

Switch 4

MSC/PSTN

Switch 5

I-Gate

4000 PRO

Dialogic I-Gate

4000 PRO

Media GatewayI-Gate

4000 PROI-Gate

4000 PRO

MSC/PSTN

Switch 3

Original Traffic

Optimized Traffic

Primary


SDH Ring 1)

Backup


(e.g. Network #2 or

SDH Ring 2)


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Application Note

13

Solution 1 Trafc Flow or Partially Unavailable Primary Network

In case of a failure in the primary transmission network that makes it partially unavailable, the trafc to be carried through the

failed links is routed by the corresponding switches to the associated I-Gate 4000 PRO Gateway terminals, which optimize and

transmit the optimized trafc over the backup network.

Figure 12 and Figure 13 are examples of two cases of partially unavailable network operating conditions, and examples of trafc

ows. In both cases, some primary network links are affected, and accordingly the corresponding trafc is transported through

the backup network. The trafc of the non-affected primary network links is transported over the primary network.

These two gures show the interswitch trafc ow transmitted from the switches to the I-Gate 4000 PRO Gateways or directly to

the primary network (solid line arrows) and the optimized trafc ow transmitted between the I-Gate 4000 PRO Gateways overthe backup network (dashed line arrows).

Figure 12. Solution 1, Case 1 Trafc Flow when Primary Network is Partially Unavailable

In the example depicted in Figure 12 (Case 1), for a given switch, all its trafc is transmitted through the backup network (switches

1, 3, and 5) or through the primary network (switches 2 and 4).

MSC/PSTN

Switch 1

MSC/PSTN

Switch 2

I-Gate

4000 PRO

MSC/PSTN

Switch 4

MSC/PSTN

Switch 5

I-Gate

4000 PRO

Dialogic I-Gate

4000 PROMedia Gateway

I-Gate

4000 PRO

I-Gate

4000 PRO

MSC/PSTN

Switch 3

Original Traffic

Optimized Traffic

PrimaryTransmission Network

(e.g. Network #1 or

SDH Ring 1)

Backup


SDH Ring 2)


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Application Note

14

In the example in Figure 13 (Case 2), for a given switch, the links that carry trafc to certain switches are affected, and the links

that carry trafc to the other switches are not affected. Accordingly, part of the switchs trafc (to certain routes) is carried through

the primary network, and part of its trafc (to other routes) is carried through the backup network.

In the example in Figure 13, the trafc between switches 2 and 5 is carried over the primary network, whereas the trafc between

switches 1, 3, and 4, as well as the trafc between switches 1, 3, and 4 and switches 2 and 5, is carried over the backup network.

Figure 13. Solution 1, Case 2 Trafc Flow when Primary Network is Partially Unavailable

MSC/PSTN

Switch 1

MSC/PSTN

Switch 2

I-Gate

4000 PRO

MSC/PSTN

Switch 4

MSC/PSTN

Switch 5

I-Gate

4000 PRO

Dialogic I-Gate

4000 PRO

Media GatewayI-Gate

4000 PROI-Gate

4000 PRO

MSC/PSTN

Switch 3

Original Traffic

Optimized Traffic

Primary


(e.g. Network #1 or

SDH Ring 1)

Backup


(e.g. Network #2 or

SDH Ring 2)


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Application Note

15

Solution 2 Backup Network Solution with Load-Sharing Mode

In Solution 1, the backup network architectural solution is based on a network protection approach comprising a primary

transmission network and a backup transmission network, where the backup network is used only when a failure takes place in

the primary network. In Solution 1, interswitch trafc is either directly transmitted over the primary transmission network (normal

primary network condition), or optimized and transmitted over the backup transmission network if the primary transmission

network has a failure condition.

For Solution 2, an alternative network architecture and trafc handling solution can be implemented, as shown in the example

in Figure 14, where the interswitch trafc is always optimized. When the primary network has no trafc-affecting failure, the

optimized trafc is split among both networks, primary and backup, and carried in load-sharing mode. This solution allows an

enhanced utilization of the bandwidth resources, in turn allowing the operator to expand the trafc-carrying capability of the

primary network with minimal CAPEX and OPEX.

Figure 14. Solution 2 Backup Transmission Network Architecture

The following sections describe three different examples of primary transmission network operating conditions for Solution 2s

trafc handling ows.

MSC/PSTN

Switch 1

MSC/PSTN

Switch 2

I-Gate

4000 PRO

MSC/PSTN

Switch 4

MSC/PSTN

Switch 5

I-Gate

4000 PRODialogic I-Gate

4000 PRO

Media Gateway

I-Gate

4000 PRO

I-Gate

4000 PRO

MSC/PSTN

Switch 3

Primary


SDH Ring 1)

Backup


SDH Ring 2)


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Application Note

16

Solution 2 Trafc Flow or Fully Available Primary Network

Figure 15 is an example of the interswitch trafc ow when the primary network has no trafc-affecting failure. The original trafc

is transmitted between the MSC or PSTN switches and the I-Gate 4000 PRO Gateways (solid line arrows), and the optimized

trafc (dashed line arrows) is split among the primary and the backup network and carried in load-sharing mode. This solution

allows signicant bandwidth savings on the primary network.

Figure 15. Solution 2 Trafc Flow when Primary Network is Fully Available

MSC/PSTNSwitch 1

MSC/PSTNSwitch 2

I-Gate

4000 PRO

MSC/PSTNSwitch 4

MSC/PSTNSwitch 5

I-Gate


4000 PRO

Media Gateway

I-Gate

4000 PRO

I-Gate

4000 PRO

MSC/PSTNSwitch 3

Original Traffic

Optimized Traffic

Primary


SDH Ring 1)

Backup


(e.g. Network #2 orSDH Ring 2)


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Application Note

17

Solution 2 Trafc Flow or Fully Unavailable Primary Network

In case of a critical failure in the primary transmission network that makes it unavailable, all of the optimized trafc from the I-Gate

4000 PRO Gateway terminals is transmitted over the backup network.


arrows) and the optimized trafc ow transmitted between the I-Gate 4000 PRO Gateways over the backup network (dashed line

arrows).

Figure 16. Solution 2 Trafc Flow when Primary Network is Fully Unavailable

In the Figure 16 example, all the primary network links are affected; accordingly, all the trafc is transported through the backup

network.

MSC/PSTN

Switch 1

MSC/PSTN

Switch 2

I-Gate

4000 PRO

MSC/PSTN

Switch 4

MSC/PSTN

Switch 5

I-Gate


4000 PRO

Media Gateway

I-Gate

4000 PRO

I-Gate

4000 PRO

MSC/PSTN

Switch 3

Original Traffic

Optimized Traffic

Primary


SDH Ring 1)

Backup


(e.g. Network #2 or

SDH Ring 2)


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Application Note

18

Solution 2 Trafc Flow or Partially Unavailable Primary Network

In case of a failure in the primary transmission network that makes the primary network partially unavailable, the corresponding

optimized interswitch trafc is transmitted between I-Gate 4000 PRO Gateways over the backup network.


arrows) and the optimized trafc ow transmitted between the I-Gate 4000 PRO Gateways over the backup network (dashed

line arrows). In this example, some primary network links are affected; accordingly, the corresponding trafc is transported in its

entirety through the backup network (long dashed line arrows). The trafc of the non-affected primary network links is split among

the primary and backup networks and carried in load-sharing mode (short dashed line arrows).

Figure 17. Solution 2 Trafc Flow when Primary Network is Partially Unavailable

MSC/PSTN

Switch 1

MSC/PSTN

Switch 2

I-Gate

4000 PRO

MSC/PSTN

Switch 4

MSC/PSTN

Switch 5

I-Gate


4000 PRO

Media Gateway

I-Gate

4000 PRO

I-Gate

4000 PRO

MSC/PSTN

Switch 3

Original Traffic

Optimized Traffic

Primary


SDH Ring 1)

Backup


SDH Ring 2)


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