Serial Interface Commands on Cisco IOS XR Software
This module describes the commands used to configure serial interfaces on routers supporting
Cisco IOS XR software.
crc (serial)
To set the length of the cyclic redundancy check (CRC) on a serial interface, use the crc command in serial configuration mode. To return the CRC setting on a serial interface to the default setting, use the no form of this command.
crc {16 | 32}
no crc {16 | 32}
Syntax Description
16 |
Sets 16-bit CRC mode. |
32 |
Sets 32-bit CRC mode. |
Defaults
The default is 16 bits for serial interfaces.
Command Modes
Serial configuration
Command History
|
|
Release 3.3.0 |
This command was introduced on the Cisco XR 12000 Series Router. |
Release 3.4.0 |
No modification. |
Release 3.5.0 |
No modification. |
Release 3.6.0 |
No modification. |
Release 3.7.0 |
No modification. |
Release 3.8.0 |
No modification. |
Usage Guidelines
To use this command, your Cisco IOS XR software system administrator must assign you to a user group associated with a task group that includes the corresponding command task IDs. If you need assistance with your task group assignment, contact your system administrator. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of Cisco IOS XR System Security Configuration Guide.
CRC is an error-checking technique that uses a calculated numeric value to detect errors in transmitted data. The designators 16 and 32 indicate the length (in bits) of the frame check sequence (FCS). A CRC of 32 bits provides more powerful error detection, but adds overhead. Both the sender and receiver must use the same setting.
CRC-16, the most widely used error checking method throughout the United States and Europe, is used extensively with WANs. CRC-32 is specified by IEEE standard 802 and as an option by some point-to-point transmission standards. It is often used on Switched Multimegabit Data Service (SMDS) networks and LANs.
Examples
In the following example, the 32-bit CRC on serial interface 0/3/0/0/0:10 is enabled:
RP/0/0/CPU0:Router(config)# interface serial 0/3/0/0/0:10
RP/0/0/CPU0:Router(config-if)# serial
RP/0/0/CPU0:Router(config-if-serial)# crc 32
Related Commands
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|
show interfaces |
Displays statistics for all interfaces configured on the router or on a specific node. |
encapsulation (serial)
To set the Layer 2 encapsulation of an interface, use the encapsulation command in interface configuration mode. To restore the system to the default encapsulation, use the no form of this command.
encapsulation {hdlc | ppp | frame-relay | mfr}
no encapsulation
Syntax Description
hdlc |
Enables Cisco High-Level Data Link Control (cHDLC) encapsulation on the interface. This is the default encapsulation type. |
ppp |
Enables Point-to-Point Protocol (PPP) encapsulation on the interface. |
frame-relay |
Enables Frame Relay encapsulation on the interface. |
mfr |
Enables multilink Frame Relay encapsulation on the interface. |
Defaults
For serial interfaces, the default encapsulation is HDLC.
Command Modes
Interface configuration
Command History
|
|
Release 2.0 |
This command was introduced on the Cisco CRS-1 router. |
Release 3.0 |
No modification. |
Release 3.2 |
This command was first supported on the Cisco XR 12000 Series Router. |
Release 3.3.0 |
No modification. |
Release 3.4.0 |
Frame Relay encapsulation was supported on serial interfaces. |
Release 3.5.0 |
No modification. |
Release 3.6.0 |
Multilink Frame Relay encapsulation was supported on serial interfaces. |
Release 3.7.0 |
No modification. |
Release 3.8.0 |
No modification. |
Usage Guidelines
To use this command, your Cisco IOS XR software system administrator must assign you to a user group associated with a task group that includes the corresponding command task IDs. If you need assistance with your task group assignment, contact your system administrator. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of Cisco IOS XR System Security Configuration Guide.
|
|
hdlc |
read, write |
interface |
read, write |
Examples
In the following example, PPP encapsulation is set on serial interface 0/3/0/1:
RP/0/RP0/CPU0:router(config)# interface serial 0/3/0/1
RP/0/RP0/CPU0:router(config-if)# encapsulation ppp
Related Commands
fragment end-to-end
To enable fragmentation of Frame Relay frames on an interface, use the fragment end-to-end command in serial Frame Relay PVC configuration mode. To disable Frame Relay fragmentation, use the no form of this command.
fragment end-to-end fragment-size
no fragment end-to-end
Syntax Description
fragment-size |
Specifies the number of payload bytes from the original Frame Relay frame that will go into each fragment. This number excludes the Frame Relay header of the original frame. All the fragments of a Frame Relay frame except the last will have a payload size equal to fragment-size; the last fragment will have a payload less than or equal to fragment-size. Valid values are from 16 to 1600 bytes. |
Defaults
The default fragment size is 53.
Command Modes
Serial Frame Relay PVC configuration mode
Command History
|
|
Release 3.5.0 |
This command was introduced on the Cisco XR 12000 Series Router. |
Release 3.6.0 |
No modification. |
Release 3.7.0 |
No modification. |
Release 3.8.0 |
No modification. |
Usage Guidelines
To use this command, your Cisco IOS XR software system administrator must assign you to a user group associated with a task group that includes the corresponding command task IDs. If you need assistance with your task group assignment, contact your system administrator. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of Cisco IOS XR System Security Configuration Guide.
Examples
The following example shows how to enter serial Frame Relay PVC configuration mode and set the fragmentation size of Frame Relay frames on subinterface 0/6/2/4.1 to 1000 bytes:
RP/0/0/CPU0:Router(config)# interface serial 0/6/2/4.1 l2transport
RP/0/0/CPU0:Router(config-if)# pvc 100
RP/0/0/CPU0:Router(config-fr-vc)# fragment end-to-end 1000
interface serial
To configure a serial interface and enter interface or subinterface configuration mode, use the interface serial command in global configuration mode.
interface serial interface-path-id[.subinterface {point-to-point | l2transport}]
Syntax Description
interface-path-id [.subinterface] |
Physical interface or virtual interface followed by the optional subinterface path ID. Naming notation is interface-path-id.subinterface. The period in front of the subinterface value is required as part of the notation. For more information about the syntax for the router, use the question mark (?) online help function. |
point-to-point |
Interface functions as one endpoint of a point-to-point link. |
l2transport |
Interface functions as one endpoint on an Layer 2 link. |
Defaults
No default behavior or values
Command Modes
Global configuration
Command History
|
|
Release 3.3.0 |
This command was introduced on the Cisco XR 12000 Series Router. |
Release 3.4.0 |
No modification. |
Release 3.5.0 |
The l2transport keyword was added to support Layer 2 configuration on serial interfaces. |
Release 3.6.0 |
No modification. |
Release 3.7.0 |
No modification. |
Release 3.8.0 |
No modification. |
Usage Guidelines
To use this command, your Cisco IOS XR software system administrator must assign you to a user group associated with a task group that includes the corresponding command task IDs. If you need assistance with your task group assignment, contact your system administrator. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of Cisco IOS XR System Security Configuration Guide.
For the interface-path-id argument, use the following guidelines:
•If specifying a physical interface, the naming notation is rack/slot/module/port. The slash between values is required as part of the notation. An explanation of each component of the naming notation is as follows:
–rack: Chassis number of the rack.
–slot: Physical slot number of the line card.
–module: Module number. A physical layer interface module (PLIM) is always 0.
–port: Physical port number of the interface.
•If specifying a virtual interface, the number range varies, depending on interface type.
Use the question mark (?) online help function following the serial keyword to view a list of all valid interface choices. To reference the serial interface on channel group 3 of T1 channel group 4 on port 2 of a SPA in subslot 1, use the following notation: interface serial 0/0/1/2/4:3.
Serial interfaces on channelized T3 can be deleted using the no channel-group command in T1 configuration mode. If there are nondefault serial parameters defined, you need to use the no interface serial command first to revert to the default configuration, and then delete the serial interface using the no channel-group command.
Examples
The following example shows how to enter interface configuration mode for a serial interface in slot 6, subslot 2, port 4, T1 channel number 10 and channel group 8:
RP/0/0/CPU0:Router(config)# interface serial 0/6/2/4/10:8
RP/0/0/CPU0:Router(config-if)#
The following example shows how to create a subinterface on a serial interface in slot 6, subslot 2, port 3 and enter subinterface configuration mode:
RP/0/0/CPU0:Router(config)# interface serial 0/6/2/3.1
RP/0/0/CPU0:Router(config-if)#
Related Commands
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|
channel-group |
Configures a T1 channel group and enter s channel group configuration mode. |
show interfaces |
Displays statistics for all interfaces configured on the router or on a specific node. |
keepalive (serial)
To set the keepalive timer for a specific serial interface, use the keepalive command in interface configuration mode. To reset the keepalive timer to the default of 10 seconds, use the no form of this command.
keepalive {seconds | disable}
no keepalive
Syntax Description
seconds |
Number of seconds that define the keepalive interval. Default is 10 seconds. |
disable |
Turns off the keepalive timer. |
Defaults
seconds: 10 seconds
Command Modes
Interface configuration
Command History
|
|
Release 2.0 |
This command was introduced on the Cisco XR 12000 Series Router. |
Release 3.0 |
No modification. |
Release 3.2 |
This command was first supported on the Cisco XR 12000 Series Router. |
Release 3.3.0 |
No modification. |
Release 3.4.0 |
No modification. |
Release 3.5.0 |
No modification. |
Release 3.6.0 |
No modification. |
Release 3.7.0 |
No modification. |
Release 3.8.0 |
No modification. |
Usage Guidelines
To use this command, your Cisco IOS XR software system administrator must assign you to a user group associated with a task group that includes the corresponding command task IDs. If you need assistance with your task group assignment, contact your system administrator. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of Cisco IOS XR System Security Configuration Guide.
cHDLC keepalives require that the keepalive command is configured the same way on both ends of a single connection. The two connected routers have no way of negotiating the keepalive value because there is no way for one router to tell the other about its configured values. The keepalive value configured on each router (local or partner) sets the rate at which the Cisco IOS XR software sends packets. It also sets the rate at which the local end expects to receive incoming packets.
To set the keepalive value to the default value, use the keepalive command without specifying a value for the seconds argument.
If three keepalives are sent to the peer and no response is received from peer, then the link makes the transition to the down state.
Examples
The following example shows how to configure keepalives for 3 seconds on serial interface 0/7/0/1:
RP/0/0/CPU0:router(config)# interface serial 0/7/0/1
RP/0/0/CPU0:router(config-if)# keepalive 3
Related Commands
|
|
show interfaces |
Displays statistics for all interfaces configured on the router or on a specific node. |
invert
To invert the data stream on a serial interface, use the invert command in serial configuration mode. To disable data inversion, use the no form of this command.
invert
no invert
Syntax Description
This command has no arguments or keywords.
Defaults
Data is not inverted.
Command Modes
Serial configuration
Command History
|
|
Release 3.3.0 |
This command was introduced on the Cisco XR 12000 Series Router. |
Release 3.4.0 |
No modification. |
Release 3.5.0 |
No modification. |
Release 3.6.0 |
No modification. |
Release 3.7.0 |
No modification. |
Release 3.8.0 |
No modification. |
Usage Guidelines
To use this command, your Cisco IOS XR software system administrator must assign you to a user group associated with a task group that includes the corresponding command task IDs. If you need assistance with your task group assignment, contact your system administrator. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of Cisco IOS XR System Security Configuration Guide.
To verify that data inversion is configured on the interface, use the show interfaces serial command.
Examples
In the following example, data inversion is enabled on serial interface 0/3/0/0/0:10:
RP/0/0/CPU0:Router(config)# interface serial 0/3/0/0/0:10
RP/0/0/CPU0:Router(config-if)# serial
RP/0/0/CPU0:Router(config-if-serial)# invert
Related Commands
|
|
show interfaces |
Displays statistics for all interfaces configured on the router or on a specific node. |
pvc (serial)
To create a Frame Relay permanent virtual circuit (PVC) under a serial subinterface and enter Frame Relay virtual circuit configuration mode, use the pvc command in subinterface configuration mode. To remove a PVC from a subinterface, use the no form of this command.
pvc dlci
no pvc dlci
Syntax Description
dlci |
DLCI number used to identify the PVC. Range is from 16 to 1007. |
Defaults
No PVC is defined.
Command Modes
Subinterface configuration
Command History
|
|
Release 3.4.0 |
This command was introduced on the Cisco XR 12000 Series Router. |
Release 3.5.0 |
No modification. |
Release 3.6.0 |
No modification. |
Release 3.7.0 |
No modification. |
Release 3.8.0 |
No modification. |
Usage Guidelines
To use this command, your Cisco IOS XR software system administrator must assign you to a user group associated with a task group that includes the corresponding command task IDs. If you need assistance with your task group assignment, contact your system administrator. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of Cisco IOS XR System Security Configuration Guide.
The pvc command creates a PVC and attaches it to the specified DLCI.
The Cisco IOS XR software dynamically creates rate queues as necessary to satisfy the requests of the PVC commands.
When you issue the pvc command in global configuration mode, the CLI prompt changes to "config-fr-vc," indicating that you have entered the Frame Relay virtual circuit configuration submode.
In the following sample output, the question mark (?) online help function displays all the commands available under the Frame Relay virtual circuit configuration submode for the serial subinterface:
RP/0/0/CPU0:router# configure
RP/0/0/CPU0:router(config)# interface serial 0/3/2/0.1
RP/0/0/CPU0:router(config-subif)# pvc 20
RP/0/0/CPU0:router(config-fr-vc)# ?
commit Commit the configuration changes to running
describe Describe a command without taking real actions
exit Exit from this submode
no Negate a command or set its defaults
show Show contents of configuration
RP/0/0/CPU0:router(config-fr-vc)#
Examples
The following example shows how to create a Frame Relay PVC on a serial subinterface, and enter Frame Relay virtual circuit configuration mode:
RP/0/0/CPU0:router# configure
RP/0/0/CPU0:router(config)# interface serial 0/6/0/1.1 point-to-point
RP/0/0/CPU0:router(config-if)# pvc 16
RP/0/0/CPU0:router(config-fr-vc)#
scramble
To enable payload scrambling (encryption) on a serial interface, use the scramble command in interface configuration mode. To disable scrambling, use the no form of this command.
scramble
no scramble
Syntax Description
This command has no arguments or keywords.
Defaults
Scrambling is disabled.
Command Modes
Interface configuration
Command History
|
|
Release 3.3.0 |
This command was introduced on the Cisco XR 12000 Series Router. |
Release 3.4.0 |
No modification. |
Release 3.5.0 |
No modification. |
Release 3.6.0 |
No modification. |
Release 3.7.0 |
No modification. |
Release 3.8.0 |
No modification. |
Usage Guidelines
To use this command, your Cisco IOS XR software system administrator must assign you to a user group associated with a task group that includes the corresponding command task IDs. If you need assistance with your task group assignment, contact your system administrator. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of Cisco IOS XR System Security Configuration Guide.
Scrambling is used to assist clock recovery on the receiving end. Scrambling is designed to randomize the pattern of 1s and 0s carried in the physical layer frame. Randomizing the digital bits can prevent continuous, nonvariable bit patterns—in other words, long strings of all 1s or all 0s. Several physical layer protocols rely on transitions between 1s and 0s to maintain clocking.
Scrambling can prevent some bit patterns from being mistakenly interpreted as alarms by switches placed between the Data Service Units (DSUs).
The local interface configuration must match the remote interface configuration. For example, if you enable scrambling on the local port, you must also do the same on the remote port.
To verify that scrambling is configured on the interface, use the show interfaces serial command.
Examples
In the following example, scrambling is enabled on serial interface 0/3/0/0/0:10:
RP/0/0/CPU0:Router(config)# interface serial 0/3/0/0/0:10
RP/0/0/CPU0:Router(config-if)# serial
RP/0/0/CPU0:Router(config-if-serial)# scramble
Related Commands
serial
To configure the serial parameters and enter serial configuration mode, use the serial command in interface configuration mode. To return to the default state of the serial interface, use the no form of this command.
serial
no serial
Syntax Description
This command has no arguments or keywords.
Defaults
No default behavior or values
Command Modes
Interface configuration
Command History
|
|
Release 3.3.0 |
This command was introduced on the Cisco XR 12000 Series Router. |
Release 3.4.0 |
No modification. |
Release 3.5.0 |
No modification. |
Release 3.6.0 |
No modification. |
Release 3.7.0 |
No modification. |
Release 3.8.0 |
No modification. |
Usage Guidelines
To use this command, your Cisco IOS XR software system administrator must assign you to a user group associated with a task group that includes the corresponding command task IDs. If you need assistance with your task group assignment, contact your system administrator. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of Cisco IOS XR System Security Configuration Guide.
Serial interfaces are automatically created for unchannelized ports; for channelized ports, serial interfaces are created when you add T1/E1 channel groups.
Examples
The following example shows how to enter serial configuration mode:
RP/0/0/CPU0:Router(config-if)# serial
RP/0/0/CPU0:Router(config-if-serial)#
transmit-delay (serial)
To specify a number of High-Level Data Link Control (HDLC) flag sequences to be inserted between the packets, use the transmit-delay command in serial configuration mode. To restore the default, use the no form of this command.
transmit-delay microseconds
no transmit-delay microseconds
Syntax Description
microseconds |
Number of microseconds of minimum delay after sending a packet. Range is from 0 to 128. Default is 0 (disabled). |
Defaults
microseconds: 0 (disabled)
Command Modes
Serial configuration
Command History
|
|
Release 3.2 |
This command was introduced on the Cisco CRS-1 router and the Cisco XR 12000 Series Router. |
Release 3.3.0 |
No modification. |
Release 3.4.0 |
No modification. |
Release 3.5.0 |
No modification. |
Release 3.6.0 |
No modification. |
Release 3.7.0 |
No modification. |
Release 3.8.0 |
No modification. |
Usage Guidelines
To use this command, your Cisco IOS XR software system administrator must assign you to a user group associated with a task group that includes the corresponding command task IDs. If you need assistance with your task group assignment, contact your system administrator. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of Cisco IOS XR System Security Configuration Guide.
Examples
In the following example, a delay of 2 microseconds is specified on serial interface 0/3/0/0/0:0:
RP/0/0/CPU0:router# configure
RP/0/0/CPU0:router(config)# interface serial 0/3/0/0/0:0
RP/0/0/CPU0:router(config-if)# serial
RP/0/0/CPU0:router(config-if-serial)# transmit-delay 2
In the following example, the transmit delay on serial interface 0/3/0/0/0:0 is disabled:
RP/0/0/CPU0:router# configure
RP/0/0/CPU0:router(config)# interface serial 0/3/0/0/0:0
RP/0/0/CPU0:router(config-if)# serial
RP/0/0/CPU0:router(config-if-serial)# no transmit-delay
Related Commands
|
|
show interfaces |
Displays statistics for all interfaces configured on the router or on a specific node. |