Configure BERT Properties

Testing interfaces allows you to troubleshoot problems and check the quality of links. You can configure any of the following interfaces to execute a bit error rate test (BERT) when the interface receives a request to run this test: E1, E3, T1, T3, the Channelized DS-3, OC-3, OC-12, and the Channelized T3, E1, STM-1, and OC-12 QPP interfaces. On all of the specified interface types, you set the duration of the test and the error rate to include in the bit stream by including the bert-period and bert-error-rate statements at the [edit interfaces interface-name interface-options] hierarchy level:

[edit interfaces interface-name interface-options]

bert-error-rate rate; 

bert-period seconds; 

seconds is the duration of the BERT procedure. The test can last from 1 through 239 seconds; the default is 10 seconds.

rate is the bit error rate. This can be an integer from 0 through 7, which corresponds to a bit error rate from 10^-0 (that is, 1 error per bit) to 10^-7 (that is, 1 error per 10 million bits).

algorithm is the pattern to send in the bit stream. The algorithm for the E1 BERT procedure is pseudo-2e15-o151 (pattern is 2¹⁵-1, as defined in the CCITT/ITU O.151 standard). On T1, E3, T3, NxDS-0, and Channelized E1 and T3 QPP interfaces, you can also select the pattern to send in the bit stream by including the bert-algorithm statement at the [edit interfaces interface-name interface-options] hierarchy level:

[edit interfaces interface-name interface-options]

bert-algorithm algorithm; 

For a list of supported algorithms, see the CLI possible completions; for example:

[edit interfaces t1-0/0/0 t1-options]

user@host# set bert-algorithm ?

Possible completions:

pseudo-2e11-o152     Pattern is 2^11 -1 (per O.152 standard)

pseudo-2e15-o151     Pattern is 2^15 - 1 (per O.152 standard)

pseudo-2e20-o151     Pattern is 2^20 - 1 (per O.151 standard)

pseudo-2e20-o153     Pattern is 2^20 - 1 (per O.153 standard)

...

See individual interface types for specific hierarchy information. For information about running the BERT procedure, see the JUNOS Internet Software Operational Mode Command Reference.

Table 9 shows the BERT capabilities for various interface types.

Table 9: BERT Capabilities by Interface Type

Interface	T1 BERT	T3 BERT	Comments
E1 or T1	Yes (port 0-3)	Yes (port 0-3)	Single port at a time Limited algorithms
E3 or T3	Yes (port 0-3)	Yes (port 0-3)	Single port at a time
Channelized OC-12	N/A	Yes (channel 0-11)	Single channel at a time Limited algorithms No bit count

For information about BERT capabilities on channelized QPP interfaces, see Channelized QPP Interface Properties.

To exchange BERT patterns between a local router and a remote router, you include the loopback remote statement in the interface configuration at the remote end of the link. From the local router, you issue the test interface command.

For more information about configuring loopbacks, see Configure E1 Loopback Capability, Configure E3 Loopback Capability, Configure SONET Loopback Capability, Configure T1 Loopback Capability, and Configure T3 Loopback Capability.

For more information about using operational mode commands to test interfaces, see the JUNOS Internet Software Operational Mode Command Reference: Interfaces.