ADTRAN 4200659L2 User Manual
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Chapter 7 Circuit and Network Redundancy

The MX2800 STS-1provides backup measures of protection for both circuit and network failure. The following sections describe the three possible modes of operation:

Non-Redundant Mode, which offers no backup protection, is described onpage 7-2.

Circuit Failure Recovery Mode, which offers backup protection in the event of controller card failure, is described onpage 7-3.

Circuit and Network Failure Recovery Mode, which offers a complete backup system for both card and network failure, is described on page 7-4.

The descriptions given include illustrations and suggested configuration settings. Please note that the settings may need modification based on your network configuration.

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Chapter 7. Circuit and Network Redundancy

NON-REDUNDANTMODE

In Non-RedundantMode, the MX2800STS-1houses only one controller card and only one network connection is available. There is no failure protection. In the event of a failure, an alarm is initiated and the front panel LEDs reflect the condition. SeeFigure 7-1for an illustration.

MX2800 STS-1

Figure 7-1.Non-RedundantMode

In this mode, the STS-1must be connected to theIN andOUT jacks forNET A.

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CIRCUIT FAILURE RECOVERY MODE

In Circuit Failure Recovery Mode, two controller cards are installed and a single STS-1line is coming in (seeFigure 7-2).In this mode, the MX2800STS-1can continue operating in the event of a controller card failure. When both cards are healthy, the primary card actively processes data while the secondary card stands by ready to take over if the first fails. The secondary card continuously monitors the line and remains framed to the incoming signal.

See Table 7-1 on page 7-4 for a list of this mode’s configuration requirements.

During a card switch, service interruption is experienced on both the STS-1and theDSX-1connections. However, since the secondary controller card remains framed to the incoming signal at all times, it is a minimal interruption.

MX2800 STS-1

Figure 7-2.Circuit Failure Recovery Mode

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Table 7-1.Configuration Requirements for Circuit Recovery

Selection Path

Recommended Setting

 

 

Config > Network Interface > XCV Threshold

1E-3(see the following note)

 

 

Config > Network Interface > Network Protection

Disabled

 

 

Config > Network Interface > Max. Switch Threshold

3

 

 

Config > Network Interface > Min. Switching Period

10 seconds

 

 

Config > T1/E1 Interface > T1/E1 Circuit Protection

Enable all or select the

 

T1/E1s that redundant

 

switching should occur on.

 

 

Config > T1/E1 Interface > XCV Threshold

1E-3(see the following note)

 

 

The XCV Threshold settings are based on the error rates considered acceptable on the STS-1orDS-1before switching.

CIRCUIT AND NETWORK FAILURE RECOVERY MODE

In this mode, two controller cards are installed and connected to two individual STS-1lines. This is, of course, the most complete mode of redundancy. In this mode, the primary controller card is connected to the primarySTS-1line and the secondary controller card is connected to the secondarySTS-1line. The primary card and line actively transmit data, while the other card and line stand by ready to take over if the first card and line fail. For example, ifCARD A fails, then control switches toCARD B andNET B.

An important feature of the MX2800 STS-1is its ability to internallyre-routethe network connection if a controller card and theopposite network connection fail. For example, in the illustration given inFigure 7-3,failedNET A is connected to healthyCARD A; and healthyNET B is connected to failedCARD B.

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In a case like this, the MX2800 STS-1is able to automatically rerouteNET B toCARD A.

The configuration requirements for this mode are the same as the ones given for Circuit Failure Recovery Mode (see Table 7-1 on page 7-4)except for theNETWORK PROTECTION setting, which must be set toENABLE.

MX2800 STS-1

Figure 7-3.Circuit and Network Failure Recovery Mode

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