Table Of Contents
T3 Bit Error Rate Testing on the Cisco 7304 Router
Related Features and Technologies
Supported Standards, MIBs, and RFCs
Configuring the Remote Port for the BERT Test
Configuring the Local Port and Starting the BERT Test
T3 Bit Error Rate Testing on the Cisco 7304 Router
Feature History
12.1(12c)EX1
This feature was introduced on the Cisco 7304 router.
12.2(18)S
This feature was introduced on Cisco 7304 routers running Cisco IOS Release 12.2 S.
This feature module describes the T3 Bit Error Rate Testing feature on the Cisco 7304 Router and includes information on the benefits of the new feature, supported platforms, configuration tasks, and a command reference.
This document includes the following sections:
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Supported Standards, MIBs, and RFCs
Feature Overview
The ratio of received bits on an interface that contain errors is called the bit error rate (BER). A bit error rate test is used to check the BER. This feature introduces bit error rate testing (BERT) for T3 line cards on the Cisco 7304 router.
T3 BERT is used on the Cisco 7304 to check communication between local and remote DS3 ports. If traffic is not being transmitted or received on a DS3 port, or if the quality of the line simply needs to be tested, T3 bit error rate testing can be used to test the port.
Benefits
Testing of DS3 Ports
The T3 BERT feature allows users to test DS3 ports when a port is unable to transmit or receive traffic or when packets are being dropped to verify the quality of the link between ports.
Related Features and Technologies
6-port T3 (DS3) line card
Related Documents
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Supported Platforms
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This documentation only covers the T3 BERT on the Cisco 7304 router. See the "Related Documents" section of this feature module for information on BERT on non-Cisco 7304 platforms.
Supported Standards, MIBs, and RFCs
Standards
No new or modified standards are supported by this feature.
MIBs
No new or modified MIBs are supported by this feature.
To obtain lists of supported MIBs by platform and Cisco IOS release, and to download MIB modules, go to the Cisco MIB website on Cisco.com at the following URL:
http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml
RFCs
No new or modified RFCs are supported by this feature.
Prerequisites
Before beginning a BERT test, ensure the following:
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This feature should work on all Cisco 7304 interfaces using a T3 line card.
Configuration Tasks
See the following sections for configuration tasks for the T3 Bit Error Rate Testing feature on the Cisco 7304 Router:
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Starting a DS3 Port BERT Test
In order to perform a BERT test on a DS3 port, the remote port must have keepalives disabled and must be set in loopback mode to return the BERT signal to the local port.
The following sections explain how to configure both the local port that initiates the BERT test and the remote port that receives and returns BERT data during the test.
Configuring the Remote Port for the BERT Test
In order to perform a BERT test on a DS3 port, the remote port needs to disable keepalives and be configured in loopback mode. The following commands show how to perform these tasks:
Configuring the Local Port and Starting the BERT Test
The following procedure shows how to initiate a BERT test on a local DS3 serial port:
Verifying BERT Configuration
The following commands can be used to verify BERT configuration:
Configuration Example
Initiating a BERT Test
In the following example, the link between serial interface 5/0 on Router A to serial interface 6/0 on Router B is being tested using BERT. The BERT test is initiated on Router B and is using pattern 2^23. The BERT test will last for 10 minutes. For the sake of this example, Router B is a Cisco 7304 router.
Remote End Configuration (Router A):
Router# configure terminalEnter configuration commands, one per line. End with CNTL/Z.Router(config)# interface serial 5/0 Router(config-if)# no keepaliveRouter(config-if)# loopback network line
Local End Configuration (Router B, a Cisco 7304 router)
Router# configure terminalEnter configuration commands, one per line. End with CNTL/Z.Router(config)# interface serial 6/0Router(config-if)# bert pattern 2^23 interval 10In the following example, a BERT test using pattern 2^23 is begun on serial interface 6/0. The BERT test will last for 10 minutes and 5 errors will be intentionally inserted into the test stream.
In this example, assume the remote end has been configured using the configuration from Router A.
Router# configure terminalEnter configuration commands, one per line. End with CNTL/Z.Router(config)# interface serial 6/0Router(config-if)# bert pattern 2^23 interval 10
Router(config-if)# bert errors 5
Verifying BERT Results
In the following example, the show controllers serial slot/interface-number bert command is used to view a BERT test that is still in progress. This command has to be entered on the router that initiated the BERT test:
Router# show controller serial 6/0 bertInterface Serial6/0 (DS3 port 1)BERT information:State :enabled (sync'd)Pattern :2^23Interval :10 minutesTime remaining :00:01:44Total errors :0Time this sync :00:08:10Errors this sync :0Sync count :1In the following example, the show controllers serial slot/interface-number bert command is used to view a BERT test that is complete. This command has to be entered on the router that initiated the BERT test.
Router# show controller serial 6/0 bertInterface Serial6/0 (DS3 port 1)BERT information:State :enabled (sync'd)Pattern :2^23Interval :10 minutesTime remaining :00:09:44Total errors :0Time this sync :00:00:10Errors this sync :0Sync count :1Command Reference
This section documents modified commands. All other commands used with this feature are documented in the Cisco IOS Release 12.1 Configuration Guide and Command Reference publications.
bert errors
To insert intentional errors into a BERT test pattern, use the bert errors command.
bert errors {number-of-errors}
Syntax Description
number-of-errors
Specifies the number of errors to insert into the current BERT test stream. If no number is specified, the number-of-errors is set to 1.
Defaults
This command is disabled by default. If a BERT test is performed, no errors are intentionally inserted into the BERT test stream unless the bert errors command is entered.
The default number-of-errors, when the bert errors command is specified without the number-of-errors option, is 1.
Command Modes
Serial interface configuration mode
Command History
12.1(12c)EX1
This command was introduced for Cisco 7304 routers.
12.2(18)S
This command was introduced on Cisco 7304 routers running Cisco IOS Release 12.2 S.
Usage Guidelines
The bert errors command is generally used to verify that the BERT test is functioning properly.
The bert errors command is used to intentionally insert errors in a BERT test stream. A BERT test stream is equal to the number of bits for a particular test (a 2^15 test is 32767 bits long, a 2^20 is 1048575 bits long, and a 2^23 is 8388607 bits long). For instance, if bert errors 5 is entered when a 2^15 test is underway, 5 errors will be inserted for each 32767 bits in the test stream.
Examples
In the following example, a BERT test using pattern 2^23 is begun on serial interface 6/0 on Router B to test the link to serial interface 5/0 on Router A. The BERT test will last for 10 minutes and 5 errors will be intentionally inserted into the test stream. For the sake of this example, assume Router B is a Cisco 7304 router.
Remote End Configuration (Router A):
Router# configure terminalEnter configuration commands, one per line. End with CNTL/Z.Router(config)# interface serial 5/0 Router(config-if)# no keepaliveRouter(config-if)# loopback network line
Local End Configuration (Router B, a Cisco 7304 Router)
Router# configure terminalEnter configuration commands, one per line. End with CNTL/Z.Router(config)# interface serial 6/0 Router(config-if)# no keepaliveRouter(config-if)# bert pattern 2^23 interval 10 Router(config-if)# bert errors 5Related CommandsRouter(config-if)# pos delay triggers path 110
Router(config-if)# bert errors 5
bert pattern
To initiate a BERT test, use the bert pattern command. To stop a test in progress, use the no bert pattern command.
bert pattern {2^15 | 2^20 | qrss | 2^23} interval minutes
no bert pattern {2^15 | 2^20 | qrss | 2^23} interval minutes
Syntax Description
Defaults
No BERT tests are performed unless this command is entered.
Command Modes
Serial interface configuration mode
Command History
12.1(12c)EX1
This command was introduced for Cisco 7304 routers.
12.2(18)S
This command was introduced on Cisco 7304 routers running Cisco IOS Release 12.2 S.
Usage Guidelines
The link being tested using T3 BERT cannot forward traffic during the BERT test. Therefore, the interfaces connected using the tested link will be set to down until the BERT test is complete. The interfaces will automatically be set to up once the BERT test is complete.
In order to perform a BERT test using the bert pattern command, the remote port has to have keepalives disabled (the no keepalive command) and be in loopback mode (the loopback network line command) Keepalives should also be disabled on the port where the BERT test is initiated.
Use the show controllers serial slot/interface-number bert command to view BERT testing results.
Examples
In the following example, the link between serial interface 5/0 on Router A to serial interface 6/0 on Router B is being tested using BERT. The BERT test is initiated on Router B and is using pattern 2^23. The BERT test will last for 10 minutes. For the sake of this example, Router B is a Cisco 7304 router.
Remote End Configuration (Router A):
Router# configure terminalEnter configuration commands, one per line. End with CNTL/Z.Router(config)# interface serial 5/0 Router(config-if)# no keepaliveRouter(config-if)# loopback network line
Local End Configuration (Router B, a Cisco 7304 router)
Router# configure terminalEnter configuration commands, one per line. End with CNTL/Z.Router(config)# interface serial 6/0Router(config-if)# bert pattern 2^23 interval 10In the following example, a BERT test using pattern 2^23 is begun on serial interface 6/0. The BERT test will last for 10 minutes and 5 errors will be intentionally inserted into the test stream.
In this example, assume the remote end has been configured using the configuration from Router A in the prior example.
Router# configure terminalEnter configuration commands, one per line. End with CNTL/Z.Router(config)# interface serial 6/0Router(config-if)# bert pattern 2^23 interval 10
Router(config-if)# bert errors 5Related CommandsRouter(config-if)# pos delay triggers path 110
Router(config-if)# bert errors 5
show controllers serial bert
To view the BERT statistics for a completed or BERT test in progress, enter the show controllers serial bert command.
show controllers serial slot/interface-number bert
Syntax Description
slot
Specifies the slot where the serial interface is located.
interface-number
Specifies the number of the serial interface.
Defaults
None.
Command Modes
EXEC
Command History
12.1(12c)EX1
This command was introduced for Cisco 7304 routers.
12.2(18)S
This command was introduced on Cisco 7304 routers running Cisco IOS Release 12.2 S.
Usage Guidelines
This command is used to view the results of a user-initiated BERT test.
Examples
In the following example, the show controllers serial slot/interface-number bert command is used to view a BERT test that is still in progress:
Router# show controller serial 6/0 bertInterface Serial6/0 (DS3 port 1)BERT information:State :enabled (sync'd)Pattern :2^23Interval :10 minutesTime remaining :00:01:44Total errors :0Time this sync :00:08:10Errors this sync :0Sync count :1In the following example, the show controllers serial slot/interface-number bert command is used to view a BERT test that is complete:
Router# show controller serial 6/0 bertInterface Serial6/0 (DS3 port 1)BERT information:State :enabled (sync'd)Pattern :2^23Interval :10 minutesTime remaining :00:09:44Total errors :0Time this sync :00:00:10Errors this sync :0Sync count :1Related CommandsRouter(config-if)# pos delay triggers path 110
Router(config-if)# bert errors 5
bert pattern
Begins a BERT test.
Inserts intention errors into a BERT test.
Glossary
alarm—A notification that a rising or falling threshold has been crossed.
trigger—An alarm which, when asserted, causes the line protocol to go down.