Configuring Link Services Physical Interfaces

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You configure link services interface properties at the logical unit and physical interface level. Default settings for link services physical interface properties are described in Default Settings for Link Services Interfaces.

The following sections explain how to configure link services physical interfaces:

For information about link services physical interface properties that can also be configured at the logical unit level, see Multilink and Link Services Logical Interface Configuration Overview.

Default Settings for Link Services Interfaces

Table 19 lists the default settings for link services statements, together with the other permitted values or value ranges.

Table 19: Link Services Physical Interface Statements for MLFR FRF.16

Option	Default Value	Possible Values
Action red differential delay	remove-link	disable-tx, remove-link
Red differential delay	120 ms	1 through 2000 ms
Yellow differential delay	72 ms	1 through 2000 ms
Drop timeout period	0 ms	0 through 2000 ms
Encapsulation	multilink-frame-relay-uni-nni	multilink-frame-relay-uni-nni
Fragmentation threshold	0 bytes	128 through 16,320 bytes (Nx64)
LMI type	itu	ansi, itu
Minimum links	1 link	1 through 8 links
MRRU	1504 bytes	1500 through 4500 bytes
n391 (full status polling counter)	6	1 through 255
n392 (LMI error threshold)	3	1 through 10
n393 (LMI monitored event count)	4	1 through 10
t391 (link integrity verify polling timer)	10	5 through 30
t392 (polling verification timer)	15	5 through 30
Sequence ID format for MLFR	12 bits	12 bits

Configuring Encapsulation for Link Services Physical Interfaces

Link services interfaces support the physical interface encapsulation MLFR UNI NNI. By default, the physical interface encapsulation on link services interfaces is MLFR UNI NNI. Multilink interfaces do not support physical interface encapsulation.

For more information, see the JUNOS Network Interfaces Configuration Guide.

You can also configure logical interface encapsulation on multilink and link services interfaces. For more information, see Configuring Encapsulation for Multilink and Link Services Logical Interfaces.

To explicitly configure link services physical interface encapsulation, include the encapsulation statement at the [edit interfaces ls-fpc/pic/port:channel] hierarchy level:


            
               encapsulation type;

You must also configure the T1, E1, or DS0 physical and physical interface with the same encapsulation type.

Configuring Acknowledgment Timers on Link Services Physical Interfaces

For link services interfaces configured with MLFR FRF.16, each link end point in a bundle initiates a request for bundle operation with its peer by transmitting an add link message. A hello message notifies the peer end point that the local end point is up. Both ends of a link generate a hello message periodically, or as configured with the hello timer. A remove link message notifies the peer that the local end management is removing the link from bundle operation. End points respond to add link, remove link, and hello messages by sending acknowledgment messages.

You can configure the maximum period to wait for an add link acknowledgment, hello acknowledgment, or remove link acknowledgment by including the acknowledge-timer statement at the [edit interfaces ls-fpc/pic/port:channel mlfr-uni-nni-bundle-options] hierarchy level:


            
               acknowledge-timer milliseconds;

The acknowledgment timer can be from 1 through 10 milliseconds. The default is 4 milliseconds.

For link services interfaces, you can configure the number of retransmission attempts to be made for consecutive hello or remove link messages after the expiration of the acknowledgment timer by including the acknowledge-retries statement at the [edit interfaces ls-fpc/pic/port:channel mlfr-uni-nni-bundle-options] hierarchy level:


            
               acknowledge-retries number;

acknowledgment-retries can be a value from 1 through 5. The default is 2.

You can configure the rate at which hello messages are sent by including the hello-timer statement at the [edit interfaces ls-fpc/pic/port:channel mlfr-uni-nni-bundle-options] hierarchy level:


            
               hello-timer milliseconds;

A hello message is transmitted after the specified period (in milliseconds) has elapsed. The hello timer can be from 1 through 180 milliseconds; the default is 10 milliseconds. When the hello timer expires, a link end point generates an add-link message.

Configuring Differential Delay Alarms on Link Services Physical Interfaces with MLFR FRF.16

For link services interfaces configured with MLFR FRF.16, the differential delay between links in a bundle is measured and warning is given when a link has a substantially greater differential delay than other links in the same bundle. The implementing endpoint can determine if the differential delay is in an acceptable range and decide to remove the link from the bundle, or to stop transmission on the link.

You can configure the yellow differential delay for links in a bundle by including the yellow-differential-delay statement at the [edit interfaces ls-fpc/pic/port:channel mlfr-uni-nni-bundle-options] hierarchy level:


            
               yellow-differential-delay milliseconds;

The yellow differential delay can be from 1 through 2000 milliseconds. The default is 72 milliseconds.

You can configure the red differential delay for links in a bundle to give warning by including the red-differential-delay statements at the [edit interfaces ls-fpc/pic/port:channel mlfr-uni-nni-bundle-options] hierarchy level:


            
               red-differential-delay milliseconds;

The red differential delay can be from 1 through 2000 milliseconds. The default is 120 milliseconds.

You can configure the action to be taken when differential delay exceeds the red limit by including the action-red-differential-delay red statements at the [edit interfaces ls-fpc/pic/port:channel mlfr-uni-nni-bundle-options] hierarchy level:


            
               action-red-differential-delay (disable-tx | remove-link);

The disable-tx option disables transmission on the link. The remove-link option removes the link from the bundle. The default action is remove-link.

You can view these settings in the output of the show interfaces extensive lsq-fpc/pic/port:channel command.

Configuring Keepalives on Link Services Physical Interfaces

You can tune the keepalive settings on the physical link-services interface. By default, the JUNOS software uses ITU Q.933 Annex A LMIs for FRF.16. To use ITU Annex A LMIs, include the lmi-type ansi statement at the [edit interfaces ls-fpc/pic/port:channel mlfr-uni-nni-bundle-options] hierarchy level:


            
               lmi-type ansi;

To configure Frame Relay keepalive parameters on a link services interface, include the n391, n392, n393, t391 and t392 statements at the [edit interfaces ls-fpc/pic/port:channel mlfr-uni-nni-bundle-options] hierarchy level:


            
               [edit interfaces ls-fpc/pic/port:channel mlfr-uni-nni-bundle-options]
               
               n391 number;
               
               n392 number;
               
               n393 number;
               
               t391 number;
               
               t392 number;

The statements determine the indicated keepalive settings:

n391—Full status polling interval. The data terminal equipment (DTE) sends a status inquiry to the data communication equipment (DCE) at the interval specified by the t391 statement. This statements sets the frequency at which the DTE requests full status report; for example, the value 10 means that the DTE requests full status report in every tenth inquiry. The intermediate inquiries request a keepalive response only. The range is 1 through 255, with a default of 6.
n392—Error threshold, which is the maximum number of errors that can occur during the number of events set by the n393 statement before the link is marked inoperative. The range is 1 through 10, with a default of 3.
n393—Monitored event count. The range is 1 through 10, with a default of 4.
t391—The interval at which the DTE requests a keepalive response from the DCE and updates status, depending on the error threshold value. The range is 5 through 30 seconds, with a default of 10 seconds.

t392—The period during which the DCE checks for keepalive responses from the DTE and updates status, depending on the DCE error threshold value. The range is from 5 through 30 seconds, with a default of 15 seconds.

Note: For the LMI to work properly, you must configure one side of a link services bundle to be a DCE.

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