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To configure the Maintenance Data Link (MDL) message defined in the ANSI T1.107a-1990 specification for the Channelized T3 Interface Processor (CT3IP) in Cisco 7500 series routers, use the mdl interface configuration command . Use the no form of this command to remove the message.
mdl {transmit {path | idle-signal | test-signal} | string {eic | lic | fic | unit | pfi | port |
transmit path | Enables transmission of the MDL Path message. |
transmit idle-signal | Enables transmission of the MDL Idle Signal message. |
transmit test-signal | Enables transmission of the MDL Test Signal message. |
string eic string | Specifies the Equipment Identification Code; can be up to 10 characters. |
string lic string | Specifies the Location Identification Code; can be up to 11 characters. |
string fic string | Specifies the Frame Identification Code; can be up to 10 characters. |
string unit string | Specifies the Unit Identification Code; can be up to 6 characters. |
string pfi string | Specifies the Facility Identification Code sent in the MDL Path message; can be up to 38 characters. |
string port string | Specifies the Port number string sent in the MDL Idle Signal message; can be up to 38 characters. |
string generator string | Specifies the Generator number string sent in the MDL Test Signal message; can be up to 38 characters. |
No MDL message is configured
Interface configuration
This command first appeared in Cisco IOS Release 11.3.
Use the show controllers t3 command to display MDL information (received strings). MDL information is displayed only when framing is set to C-bit.
The following examples show several of the mdl commands for the CT3IP in slot 9:
controller t3 9/0/0 mdl string eic Router A mdl string lic Test Network mdl string fic Building B mdl string unit ABC
You can use the master index or search online for documentation of related commands.
To specify the physical connection on an interface, use the media type interface configuration command. Use the no form of this command to restore the default value.
media-type {aui | 10baset | 100baset | mii}
aui | Selects a 15-pin physical connection. |
10baset | Selects an R-J45 10BaseT physical connection. |
100baset | Specifies an RJ-45 100BaseT physical connection. |
mii | Specifies a media-independent interface. |
AUI 15-pin physical connection is the default setting on the Cisco 4000 series.
100BaseT physical connection is the default setting on the Cisco 7000 series and 7200 series.
Interface configuration
This command first appeared in Cisco IOS Release 10.0.
To specify the physical connection on an interface, use the following interface configuration:
The following example selects an RJ-45 10BaseT physical connection on Ethernet interface 1:
interface ethernet 1
media-type 10baset
The following example specifies a media-independent interface physical connection to Fast Ethernet slot 0, port 1 on the Cisco 7000 or 7200 series:
interface fastethernet 0/1 media-type mii
The following example specifies a media-independent interface physical connection to Fast Ethernet slot 0, port adapter 1, port 1 on the Cisco 7500 series:
interface fastethernet 0/1/1 media-type mii
Use the mop enabled interface configuration command to enable an interface to support the Maintenance Operation Protocol (MOP). To disable MOP on an interface, use the no form of this command.
mop enabledThis command has no arguments or keywords.
Enabled on Ethernet interfaces and disabled on all other interfaces.
Interface configuration
This command first appeared in Cisco IOS Release 10.0.
The following example enables MOP for serial interface 0:
interface serial 0 mop enabled
You can use the master indexes or search online to find documentation of related commands.
mop retransmit-timer
mop retries
mop sysid
To enable an interface to send out periodic Maintenance Operation Protocol (MOP) system identification messages, use the mop sysid interface configuration command. To disable MOP message support on an interface, use the no form of this command.
mop sysidThis command has no arguments or keywords.
Enabled
Interface configuration
This command first appeared in Cisco IOS Release 10.0.
You can still run MOP without having the background system ID messages sent. This lets you use the MOP remote console, but does not generate messages used by the configurator.
The following example enables serial interface 0 to send MOP system identification messages:
interface serial 0 mop sysid
You can use the master indexes or search online to find documentation of related commands.
mop device-code
mop enabled
To adjust the maximum packet size or maximum transmission unit (MTU) size, use the mtu interface configuration command. Use the no form of this command to restore the MTU value to its original default value.
mtu bytes
bytes | Desired size in bytes. |
Table 11 lists default MTU values according to media type.
| Media Type | Default MTU |
|---|---|
Ethernet | 1500 |
Serial | 1500 |
Token Ring | 4464 |
ATM | 4470 |
FDDI | 4470 |
HSSI (HSA) | 4470 |
Interface configuration
This command first appeared in Cisco IOS Release 10.0.
Each interface has a default maximum packet size or maximum transmission unit (MTU) size. This number generally defaults to the largest size possible for that type interface. On serial interfaces, the MTU size varies, but cannot be set smaller than 64 bytes.
 | Caution
Changing an MTU size on a Cisco 7500 series router results in recarving of buffers and resetting of all interfaces. The following message is displayed: |
The following example specifies an MTU of 1000 bytes:
interface serial 1
mtu 1000
You can use the master indexes or search online to find documentation of related commands
encapsulation smds
ip mtu
To set the E3 national bit in the G.751 frame used by the PA-E3 port adapter, use the national bit interface configuration command. To return to the default E3 national bit, use the no form of this command.
national bit {0 | 1}
0 | 1 | Specifies the E3 national bit in the G.751 frame. The default is 0. |
0 national bit
Interface configuration
This command first appeared in Cisco IOS Release 11.1 CA.
The national bit command sets bit 12 in the E3 frame.
To verify the national bit configured on the interface, use the show controller serial EXEC command.
The following example sets the national bit to 1 on the PA-E3 port adapter in slot 1, port adapter slot 0, interface 0:
interface serial 1/0/0 national bit 1
You can use the master indexes or search online to find documentation of related commands.
international bit
show controllers serial
Use the nrzi-encoding interface configuration command to enable nonreturn-to-zero inverted (NRZI) line-coding format. Use the no form of this command to disable this capability.
nrzi-encoding [mark]
mark | (Optional) Specifies that NRZI mark encoding is required on the PA-8T and PA-4T+ synchronous serial port adapters on Cisco 7200 and 7500 series routers. If mark is not specified, NRZI space encoding is used. |
Disabled
Interface configuration
This command first appeared in Cisco IOS Release 10.0.
This command was modified in Cisco IOS Release 11.3 to include the mark keyword for the Cisco 7200 series routers and Cisco 7500 series routers.
The following example configures serial interface 1 for NRZI encoding:
interface serial 1 nrzi-encoding
The following example configures serial interface 3/1/0 for NRZI mark encoding:
interface serial 3/1/0 nrzi-encoding mark
To specify the mode of a slow-speed serial interface on a router as either synchronous or asynchronous, use the physical-layer interface configuration command. To return the interface to the default mode of synchronous, use the no form of this command.
physical-layer {sync | async}
sync | Places the interface in synchronous mode. |
async | Places the interface in asynchronous mode. |
Synchronous mode
Interface configuration
This command first appeared in Cisco IOS Release 11.2.
This command applies only to low-speed serial interfaces available on Cisco 2520 through 2523 routers.
If you specify the no physical-layer command, you return the interface to its default mode (synchronous).
In synchronous mode, low-speed serial interfaces support all interface configuration commands available for high-speed serial interfaces, except the following two commands:
When placed in asynchronous mode, low-speed serial interfaces support all commands available for standard asynchronous interfaces.
When you enter this command, it does not appear in the output of more system:running-config more nvram:startup-config commands because the command is a physical layer command.
This example changes a low-speed serial interface from synchronous to asynchronous mode:
interface serial 2 physical-layer async
To enable an interface on a PA-4R-DTR port adapter to operate as a concentrator port, use the port interface configuration command. Use the no form of this command to restore the default station mode.
portThis command has no arguments or keywords.
Station mode
Interface configuration
This command first appeared in Cisco IOS Release 11.3(3)T.
By default, the interfaces of the PA-4R-DTR operate as Token Ring stations. Station mode is the typical operating mode. Use this command to enable an interface to operate as a concentrator port.
The following example configures the PA-4R-DTR ports to operate in concentrator mode on a Cisco 7000 series router:
router# configure terminal router(config)# interface tokenring 3/0/0 router(config-if)# port
To set the SONET overhead bytes in the frame header to meet a specific standards requirement or to ensure interoperability with another vendor's equipment, use the pos flag interface configuration command. To remove the setting of the SONET overhead bytes, use the no form of this command.
pos flag {c2 | j0 | s1s0} value
c2 value | Path signal identifier used to identify the payload content type. |
j0 value | Section trace byte (formerly the C1 byte). For interoperability with SDH equipment in Japan, use the value 0x1. The byte value can be 0 to 255. |
sls0 value | S1 and S0 bits (bits 5 and 6 of the H1 #1 payload pointer byte). Use the following values to tell the SONET transmission equipment the SS bit: · For OC-3c, use 0 (this is the default). · For AU-4 container in SDH, use 2. The S1 and S0 bits can be 0 to 3. Values 1 and 3 are undefined. |
The default c2 value is 0xCF, and the default sls0 value is 0.
Interface configuration
This command was added in Cisco IOS Release 11.2 GS to support the Cisco 12000 series Gigabit Switch Routers.
Use the following values to tell the SONET transmission equipment the payload type:
The following example sets the path signal identifier used to identify the payload content type to ATM on the pos interface in slot 9:
Router(config)# interface pos 9/0
Router(config-if)# pos flag c2 0x13
Router(config-if)# end
Router#
To specify the framing used on the POS interface, use the pos framing interface configuration command. To return to the default SONET STS-3c framing mode, use the no form of this command.
pos framing {sdh | sonet}
sdh | Selects SDH STM-1 framing. This framing mode is typically used in Europe. |
sonet | Selects SONET STS-3c framing. This is the default. |
SONET STS-3c framing
Interface configuration
This command first appeared in Cisco IOS Release 11.2.
This command was modified in Cisco IOS Release 11.3 to change the posi framing-sdh command to pos framing-sdh.
This command was modified in Cisco IOS Release 11.2 GS (Cisco IOS Release 11.2 GS was after Cisco IOS Release 11.3) to change the command syntax from pos framing-sdh to pos framing and add the sonet keyword.
The following example configures the interface for SDH STM-1 framing:
interface pos 3/0 pos framing-sdh no shutdown
You can use the master indexes or search online to find documentation of related commands.
interface pos
pos internal-clock
The clock source (interface) command replaces this command. Refer to the description of clock source for information on transmit clock source.
To permit selected SONET alarms to be logged to the console for a POS interface, use the pos report interface configuration command. To disable logging of select SONET alarms, use the no form of this command.
pos report {b1-tca | b2-tca | b3-tca | lais | lrdi | pais | plop | prdi | rdool | sd-ber | sf-ber |
b1-tca | Reports B1 bit error rate (BER) threshold crossing alarm errors. Reported by default. |
b2-tca | Reports B2 BER threshold crossing alarm errors. Reported by default. |
b3-tca | Reports B3 BER threshold crossing alarm errors. Reported by default. |
lais | Reports line alarm indication signal errors. |
lrdi | Reports line remote defect indication errors. |
pais | Reports path alarm indication signal errors. |
plop | Reports path loss of pointer errors. Reported by default. |
prdi | Reports path remote defect indication errors. |
rdool | Reports receive data out of lock errors. |
sd-ber | Reports signal degradation BER errors. |
sf-ber | Reports signal failure BER errors. Reported by default. |
slof | Reports section loss of frame errors. Reported by default. |
slos | Reports section los of signal errors. Reported by default. |
b1-tca, b2-tca, b3-tca, plop, sf-ber, slof, and slos are reported by default.
Interface configuration
This command first appeared in Cisco IOS Release 11.1 CC.
Reporting an alarm means that the alarm can be logged to the console. Just because an alarm is permitted to be logged does not guarantee that it is logged. SONET alarm hierarchy rules dictate that only the most severe alarm of an alarm group is reported. Whether an alarm is reported or not, you can view the current state of a defect by checking the "Active Defects" line from the show controllers pos command output. A defect is a problem indication that is a candidate for an alarm.
For B1, the bit interleaved parity error report is calculated by comparing the BIP-8 code with the BIP-8 code extracted from the B1 byte of the following frame. Differences indicate that section level bit errors have occurred.
For B2, the bit interleaved parity error report is calculated by comparing the BIP-8/24 code with the BIP-8 code extracted from the B2 byte of the following frame. Differences indicate that line level bit errors have occurred.
For B3, the bit interleaved parity error report is calculated by comparing the BIP-8 code with the BIP-8 code extracted from the B3 byte of the following frame. Differences indicate that path level bit errors have occurred.
PAIS is sent by line terminating equipment (LTE) to alert the downstream path terminating equipment (PTE) that it has detected a defect on its incoming line signal.
PLOP is reported as a result of an invalid pointer (H1, H2) or an excess number of new data flag (NDF) enabled indications.
SLOF is detected when a severely error framing (SEF) defect on the incoming SONET signal persists for 3 milliseconds.
SLOS is detected when an all-zeros pattern on the incoming SONET signal lasts 19(+-3) microseconds or longer. This defect might also be reported if the received signal level drops below the specified threshold.
To determine the alarms that are reported on the interface, use the show controllers pos command.
The following example enables reporting of SD-BER and LAIS alarms on the interface:
Router(config)# interface pos 3/0/0
Router(config-if)# pos report sd-ber
Router(config-if)# pos report lais
Router(config-if)# end
Router#
You can use the master indexes or search online to find documentation of related commands.
interface pos
show controllers pos
To enable SONET payload scrambling on a POS interface, use the pos scramble-atm interface configuration command. To disable scrambling, use the no form of this command.
pos scramble-atmThis command has no keywords or arguments.
Scrambling is disabled
Interface configuration
This command first appeared in Cisco IOS Release 11.1 CA and then was added to Cisco IOS Release 11.2 P.
SONET payload scrambling applies a self-synchronous scrambler (x^43+1) to the Synchronous Payload Envelope (SPE) of the interface to ensure sufficient bit transition density. Both ends of the connection must use the same scrambling algorithm. When enabling POS scrambling on a VIP2 POSIP on the Cisco 7500 series that has a hardware revision of 1.5 or higher, you can specify CRC 16 only (that is, CRC 32 is currently not supported).
To determine the hardware revision of the POSIP, use the show diag command.
The POS interface on the Cisco 12000 series has no restrictions.
To determine whether scrambling is enabled on the interface, use the show interface pos command or more nvram:startup-config command.
The following example enables scrambling on the interface:
Router(config)# interface pos 3/0
Router(config-if)# pos scramble-atm
Router(config-if)# no shutdown
Router(config-if)# end
Router#
You can use the master indexes or search online to find documentation of related commands.
interface pos
more nvram:startup-config
show interface pos
To set the BER threshold values of the specified alarms for a POS interface, use the pos threshold interface configuration command. To return to the default setting, use the no form of this command.
pos threshold {b1-tca | b2-tca | b3-tca | sd-ber | sf-ber} rate
b1-tca | B1 bit error rate (BER) threshold crossing alarm. |
b2-tca | B2 BER threshold crossing alarm. |
b3-tca | B3 BER threshold crossing alarm. |
sd-ber | Signal degrade BER threshold. |
sf-ber | Signal failure BER threshold. |
rate | Bit error rate from 3 to 9 (10-n). The default is 6 for all thresholds except for the sf-ber. For sf-ber, the default is 3 (that is, 10e-3). |
The default is 6 for b1-tca, b2-tca, b3-tca, and sd-ber. The default is 3 for sf-ber.
Interface configuration
This command first appeared in Cisco IOS Release 11.1 CC.
For B1, the bit interleaved parity error report is calculated by comparing the BIP-8 code with the BIP-8 code extracted from the B1 byte of the following frame. Differences indicate that section level bit errors have occurred.
For B2, the bit interleaved parity error report is calculated by comparing the BIP-8/24 code with the BIP-8 code extracted from the B2 byte of the following frame. Differences indicate that line level bit errors have occurred.
For B3, the bit interleaved parity error report is calculated by comparing the BIP-8 code with the BIP-8 code extracted from the B3 byte of the following frame. Differences indicate that path level bit errors have occurred.
SF-BER and SD-BER are sourced from B2 BIP-8 error counts (as is B2-TCA). However, SF-BER and SD-BER feed into the APS machine and can lead to a protection switch (if APS is configured).
B1-TCA, B2-TCA, and B3-TCA do nothing more than print a log message to the console (if reports for them are enabled).
To determine the BER thresholds configured on the interface, use the show controllers pos command.
The following example configures thresholds on the interface:
Router(config)# interface pos 3/0/0
Router(config-if)# pos threshold sd-ber 8
Router(config-if)# pos threshold sf-ber 4
Router(config-if)# pos threshold b1_tca 4
Router(config-if)# end
Router#
You can use the master indexes or search online to find documentation of related commands.
interface pos
show controllers pos
To specify ISDN Primary Rate Interface (PRI) on a channelized E1 or T1 card on Cisco 7500 series router, use the pri-group controller configuration command. Use the no form of this command to remove the ISDN PRI.
pri-group [timeslots range]
timeslots range | (Optional) Specifies a single range of values from 1 to 23. |
Disabled
Controller configuration
This command first appeared in Cisco IOS Release 11.0.
When you configure ISDN PRI, you must first specify an ISDN switch type for PRI and an E1 or T1 controller.
The following example specifies ISDN PRI on T1 slot 1, port 0:
isdn switch-type primary-4ess
controllers t1 1/0
framing esf linecode b8zs
pri-group timeslots 2-6
You can use the master indexes or search online to find documentation of related commands.
controller e1
controller t1
interface serial
isdn switch-type
To enable pulsing DTR signal intervals on the serial interfaces, use the pulse-time interface configuration command. Use the no form of this command to restore the default interval.
pulse-time seconds
seconds | Integer that specifies the DTR signal interval in seconds. |
0 seconds
Interface configuration
This command first appeared in Cisco IOS Release 10.0.
When the serial line protocol goes down (for example, because of loss of synchronization) the interface hardware is reset and the DTR signal is held inactive for at least the specified interval. This function is useful for handling encrypting or other similar devices that use the toggling of the DTR signal to resynchronize.
The following example enables DTR pulse signals for three seconds on serial interface 2:
interface serial 2
pulse-time 3
To set the ring speed for the CSC-1R and CSC-2R Token Ring interfaces, use the ring-speed interface configuration command.
ring-speed speed
speed | Integer that specifies the ring speed, either 4 for 4-Mbps or 16 for 16-Mbps operation. |
16-Mbps operation
| Caution Configuring a ring speed that is wrong or incompatible with the connected Token Ring causes the ring to beacon, which effectively takes the ring down and makes it nonoperational. |
Interface configuration
This command first appeared in Cisco IOS Release 10.0.
The following example sets a Token Ring interface ring speed to 4 Mbps:
interface tokenring 0
ring-speed 4
To enable scrambling of the payload on the PA-E3 port adapter and the PA-T3 port adapter, use the scramble interface configuration command. To disable scrambling, use the no form of this command.
scrambleThis command has no arguments or keywords.
Scrambling is disabled.
Interface configuration
This command first appeared in Cisco IOS Release 11.1 CA.
E3/T3 scrambling is used to assist clock recovery on the receiving end.
Scrambling can prevent some bit patterns from being mistakenly interpreted as alarms by switches placed between the 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 scramble is configured on the interface, use the show controllers serial EXEC command.
The following example enables scrambling on the PA-E3 port adapter in slot 1, port adapter slot 0, interface 0:
interface serial 1/0/0 scramble
You can use the master indexes or search online to find documentation of related commands.
To configure the network line speed for a serial interface on a 4-wire, 56/64-kbps CSU/DSU module, use the service-module 56k clock rate interface configuration command. Use the no form of this command to enable a network line speed of 56 kbps, which is the default.
service-module 56k clock rate speed
speed | Network line speed in kbps. The default speed is 56 kbps. Choose from one of the following optional speeds: · 2.4---2400 kbps · 4.8---4800 kbps · 9.6---9600 kbps · 19.2---19200 kbps · 38.4---38400 kbps · 56---56000 kbps · 64---64000 kbps · auto---Automatic line speed mode. Configure this option if your line speed is constantly changing. |
56 kbps
Interface configuration
This command first appeared in Cisco IOS Release 11.2.
The 56-kbps line speed is available in switched mode, which is enabled using the service-module 56k network-type interface configuration command on the 4-wire CSU/DSU. If you have a 2-wire CSU/DSU module, the default is automatically set to switched mode.
The 64-kbps line speed cannot be used with back-to-back digital data service (DDS) lines. The subrate line speeds are determined by the service provider.
The keyword auto enables the CSU/DSU to decipher current line speed from the sealing current running on the network. Use auto only when transmitting over telco DDS lines and the clocking source is taken from the line.
The following example displays two routers connected in back-to-back DDS mode. However, notice that at first the configuration fails because the auto option is used. Later in the example the correct matching configuration is issued, which is 38.4 kbps.
Router1(config)# interface serial 0
Router1(config-if)#service-module 56k clock source internal
Router1(config-if)#service-module 56k clock rate 38.4
Router2(config-if)#service-module 56k clock rate auto
a1#ping 10.1.1.2
Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 10.1.1.2, timeout is 2 seconds: ..... Success rate is 0 percent (0/5) Router2(config-if)#service-module 56k clock rate 38.4 Router1#ping 10.1.1.2
Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 10.1.1.2, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 52/54/56 ms
When transferring from DDS mode to switched mode, you must set the correct clock rate, as shown in the following example:
Router2(config-if)#service-module 56k network-type dds
Router2(config-if)#service-module 56k clock rate 38.4
Router2(config-if)#service-module 56k network-type switched
% Have to use 56k or auto clock rate for switched mode % Service module configuration command failed: WRONG FORMAT. Router2(config-if)#service-module 56k clock rate auto
% WARNING - auto rate will not work in back-to-back DDS. Router2(config-if)#service-module 56k network-type switched
You can use the master indexes or search online to find documentation of related commands.
service-module 56k clock source
service-module 56k network-type
To set up the clock source on a serial interface for a 4-wire, 56/64-kbps CSU/DSU module, use the service-module 56k clock source interface configuration command. Use the no form of this command to specify the clocking come from line.
service-module 56k clock source {line | internal}
line | Uses the clocking provided by the active line coming in to the router. |
internal | Uses the internal clocking provided by the hardware module. |
Line clock
Interface configuration
This command first appeared in Cisco IOS Release 11.2.
In most applications, the CSU/DSU should be configured with the clock source line command. For back-to-back configurations, configure one CSU/DSU with the clock source internal command and the other with clock source line command.
The following example configures internal clocking and transmission speed at 38.4 kbps.
router(config)# interface serial 0
router(config-if)# service-module 56k clock source internal
router(config-if)# service-module 56k clock rate 38.4
You can use the master indexes or search online to find documentation of related commands.
service-module 56k clock rate
To prevent application data from replicating loopback codes when operating at 64 kbps on a 4-wire CSU/DSU, use the service-module 56k data-coding interface configuration command. Use the no form of this command to enable normal transmission.
service-module 56k data-coding {normal | scrambled}
normal | Specifies normal transmission of data. |
scrambled | Scrambles bit codes or user data before transmission. All control codes such as out of service and out of frame are avoided. |
Normal data transmission
Interface configuration
This command first appeared in Cisco IOS Release 11.2.
Enable the scrambled configuration only in 64-kbps digital data service (DDS) mode. If the network type is set to switched, the configuration is refused.
If you transmit scrambled bit codes, both CSU/DSUs must have this command configured for successful communication.
The following example scrambles bit codes or user data before transmission:
router(config)# interface serial 0
router(config-if)# service-module 56k clock rate 64
router(config-if)# service-module 56k data-coding scrambled
You can use the master indexes or search online to find documentation of related commands.
service-module 56k clock rate
To transmit packets in switched dial-up mode or digital data service (DDS) mode using a serial interface on a 4-wire, 56/64-kbps CSU/DSU module, use the service-module 56k network-type interface configuration command. Use the no form of this command to transmit from a dedicated leased line in DDS mode.
service-module 56k network-type {dds | switched}
dds | Transmits packets in DDS mode or through a dedicated leased line. |
switched | Transmits packets in switched dial-up mode. On a 2-wire, switched 56-kbps CSU/DSU module this is the default and only setting. |
DDS is enabled for the 4-wire CSU/DSU.
Switched is enabled for the 2-wire CSU/DSU.
Interface configuration
This command first appeared in Cisco IOS Release 11.2.
In switched mode, you need additional dialer configuration commands to configure dial-out numbers. Before you enable the service-module 56k network-type switched command, both CSU/DSUs must use a clock source coming from the line and the clock rate configured to auto or 56 kbps. If the clock rate is not set correctly, this command will not be accepted.
The 2-wire and 4-wire, 56/64-kbps CSU/DSU modules use V.25 bis dial commands to interface with the router. Therefore, the interface must be configured using the dialer in-band command. DTR dial is not supported.
The following example configures transmission in switched dial-up mode:
router(config)# interface serial 0
router(config-if)#service-module 56k clock rate auto
router(config-if)#service-module 56k network-type switched
router(config-if)#dialer in-band
router(config-if)#dialer string 2576666
router(config-if)#dialer-group 1
You can use the master indexes or search online to find documentation of related commands.
dialer in-band
service-module 56k clock rate
service-module 56k clock source
service-module 56k switched-carrier
To enable the acceptance of a remote loopback request on a serial interface on a 2- or 4-wire, 56/64-kbps CSU/DSU module, use the service-module 56k remote-loopback interface configuration command. Use the no form of this command to disable the module from entering loopback.
service-module 56k remote-loopbackThis command has no arguments or keywords.
Enabled
Interface configuration
This command first appeared in Cisco IOS Release 11.2.
The no service-module 56k remote-loopback command prevents the local CSU/DSU from being placed into loopback by remote devices on the line. The line provider is still able to put the module into loopback by reversing sealing current. Unlike the T1 module, the 2- or 4-wire, 56/64-kbps CSU/DSU module can still initiate remote loopbacks with the no form of this command configured.
The following example enables transmitting and receiving remote loopbacks:
router(config)# interface serial 0
router(config-if)# service-module 56k remote-loopback
You can use the master indexes or search online to find documentation of related commands.
loopback remote (interface)
To select a service provider to use with a 2- or 4-wire, 56/64 kbps dial-up serial line, use the service-module 56k switched-carrier interface configuration command. Use the no form of this command to enable the default service provider.
service-module 56k switched-carrier {att | sprint | other}
att | AT&T or other digital network service provider. |
sprint | Sprint or other service provider whose network requires echo cancelers. |
other | Any other service provider. |
ATT is enabled on the 4-wire, 56/64-kbps CSU/DSU module.
Sprint is enabled on the 2-wire, switched 56-kbps CSU/DSU module.
Interface configuration
This command first appeared in Cisco IOS Release 11.2.
On a Sprint network, echo-canceler tones are sent during call setup to prevent the echo cancelers from damaging digital data. The transmission of echo-canceler tones may increase call setup times by 8 seconds on the 4-wire module. Having echo cancellation enabled does not affect data traffic.
This configuration command is ignored if the network type is DDS.
The following example configures AT&T as a service provider:
router(config)# interface serial 0
router(config-if)# service-module 56k network-type switched
router(config-if)# service-module 56k switched-carrier att
You can use the master indexes or search online to find documentation of related commands.
service-module 56k network-type
To specify the clock source for the fractional T1/T1 CSU/DSU module, use the service-module t1 clock source interface configuration command. Use the no form of this command to return to the default line clock.
service-module t1 clock source {internal | line}
internal | Specifies the CSU/DSU internal clock. |
line | Specifies the line clock. |
Line clock
Interface configuration
This command first appeared in Cisco IOS Release 11.2.
The following example sets an internal clock source on serial line 0:
router(config)# interface serial 0
router(config-if)# service-module t1 clock source line
You can use the master indexes or search online to find documentation of related commands.
service-module 56k clock source
To guarantee the ones density requirement on an AMI line using the fractional T1/T1 module, use the service-module t1 data-coding inverted interface configuration command. Use the no form of this command to enable normal data transmission.
service-module t1 data-coding {inverted | normal}
inverted | Inverts bit codes by changing all 1 bits into 0 bits and all 0 bits into 1 bits. |
normal | Requests that no bit codes be inverted before transmission. |
Normal transmission
Interface configuration
This command first appeared in Cisco IOS Release 11.2.
Data inversion is used to guarantee the ones density requirement on an AMI line when using bit-oriented protocols such as High-Level Data Link Control (HDLC), Point-to-Point Protocol (PPP), X.25, and Frame Relay. If the timeslot speed is set to 56 kbps, this command is rejected because line density is guaranteed when transmitting at 56 kbps. Use this command with the 64-kbps line speed.
If you transmit inverted bit codes, both CSU/DSUs must have this command configured for successful communication.
The following example inverts bit codes using a timeslot speed of 64 kbps:
router(config)# interface serial 0
router(config-if)# service-module t1 timeslots all speed 64
router(config-if)# service-module t1 data-coding inverted
You can use the master indexes or search online to find documentation of related commands.
service-module t1 linecode
service-module t1 timeslots
To set the fdl parameter to either att or ansi, use the service-module t1 fdl inteface configuration command. Use the no form of this command to ignore the fdl parameter.
service-module t1 fdl {ansi | att}
ansi | Sets the fdl parameter to ansi. |
att | Sets the fdl parameter to att. |
Determined by the telephone company.
Interface configuration mode
This command first appeared in Cisco IOS Release 11.2 P.
The default is no service-module t1 fdl. The ansi or att options are determined by your service provider or telephone company.
To select the frame type for a line using the fractional T1/T1 (FT1/T1) module, use the service-module t1 framing interface configuration command. Use the no form of this command to revert to the default, which is Extended Superframe.
service-module t1 framing {esf | sf}
esf | Specifies Extended Super Frame as the T1 frame type. |
sf | Specifies D4 Super Frame as the T1 frame type. |
Extended Superframe (ESF)
Interface configuration
This command first appeared in Cisco IOS Release 11.2.
Use this command in configurations where the router communicates with FT1/T1 data lines. The service provider determines which framing type, either esf or sf, is required for your circuit.
The following example enables Super Frame as the FT1/T1 frame type:
service-module t1 framing sf
To configure the CSU line build out (LBO) on a fractional T1/T1 CSU/DSU module, use the service-module t1 lbo interface configuration command. Use the no form of this command to disable line build out.
service-module t1 lbo {-15 db | -7.5 db | none}
-15 db | Decreases outgoing signal strength by 15 dB. |
-7.5 db | Decreases outgoing signal strength by 7.5 dB. |
none | Transmits packets without decreasing outgoing signal strength. |
No line build out
Interface configuration
This command first appeared in Cisco IOS Release 11.2.
Use this command to decrease the outgoing signal strength to an optimum value for a fractional T1 line receiver. The ideal signal strength should be -15 dB to -22 dB, which is calculated by adding the phone company loss + cable length loss + line build out.
You may use this command in back-to-back configurations, but it is not needed on most actual T1 lines.
The following example sets the LBO to -7.5 dB:
router(config)# interface serial 0
router(config-if)# service-module t1 lbo -7.5db
To select the line code for the fractional T1/T1 module, use the service-module t1 linecode interface configuration command. Use the no form of this command to select the default, which is the B8ZS line code.
service-module t1 linecode {ami | b8zs}
ami | Specifies alternate mark inversion (AMI) as the line code. |
b8zs | Specifies binary 8 zero substitution (B8ZS) as the line code. |
b8zs
Interface configuration
This command first appeared in Cisco IOS Release 11.2.
Configuring B8ZS is a method of ensuring the ones density requirement on a T1 line by substituting intentional bipolar violations in bit positions four and seven for a sequence of eight zero bits. When the CSU/DSU is configured for AMI, you must guarantee the ones density requirement in your router configuration using the service-module t1 data-coding inverted command or the service-module t1 timeslots speed 56 command.
Your T1 service provider determines which line code, either ami or b8zs, is required for your T1 circuit.
The following example specifies AMI as the line code:
router(config)# interface serial 0
router(config-if)# service-module t1 linecode ami
You can use the master indexes or search online to find documentation of related commands.
service-module t1 data-coding
service-module t1 timeslots
To generate remote alarms (yellow alarms) at the local CSU/DSU or detect remote alarms sent from the remote CSU/DSU, use the service-module t1 remote-alarm-enable interface configuration command. Use the no form of this command to disable remote alarms.
service-module t1 remote-alarm-enableThis command has no arguments or keywords.
Remote alarms disabled
Interface configuration
This command first appeared in Cisco IOS Release 11.2.
Remote alarms are transmitted by the CSU/DSU when it detects an alarm condition, such as a red alarm (loss of frame) or blue alarm (unframed ones). The receiving CSU/DSU then knows there is an error condition on the line.
With D4 Super Frame configured, a remote alarm condition is transmitted by setting the bit 2 of each time slot to zero. For received user data that has the bit 2 of each time slot set to zero, the CSU/DSU interprets the data as a remote alarm and interrupts data transmission, which explains why remote alarms are disabled by default. With Extended Super Frame configured, the remote alarm condition is signalled out of band in the facilities data link.
You can see if the FT1/T1 CSU/DSU is receiving a remote alarm (yellow alarm) by issuing the show service-module command.
The following example enables remote alarm generation and detection:
router(config)# interface serial 0
router(config-if)# service-module t1 remote-alarm-enable
You can use the master indexes or search online to find documentation of related commands.
service-module t1 framing
To specify if the fractional T1/T1 CSU/DSU module enters loopback mode when it receives a loopback code on the line, use the service-module t1 remote-loopback interface configuration command. Use the no form of this command to disable remote loopbacks.
service-module t1 remote-loopback {full | payload} [alternate | v54]
full | Configures the remote loopback code used to transmit or accept CSU loopback requests. |
payload | Configures the loopback code used by the local CSU/DSU to generate or detect payload-loopback commands. |
alternate | (Optional) Transmits a remote CSU/DSU loopback request using a 4-in-5 pattern for loopup and 2-in-3 pattern for loopdown. This is an inverted version of the standard loopcode request. |
v54 | (Optional) Industry standard loopback code. Use this configuration for CSU/DSUs that may not support the Accunet loopup standards. This keyword is used only with a payload request, not a full request. |
Full and payload loopbacks with standard-loopup codes
Interface configuration
This command first appeared in Cisco IOS Release 11.2.
You can simultaneously configure the full and payload loopback points. However, only one loopback code can be configured at a time. For example, if you configure the service-module t1 remote-loopback payload alternate command, a payload v54 request cannot be transmitted or accepted.
The no form of this command disables loopback requests. For example, the no service-module t1 remote-loopback full command ignores all full-bandwidth loopback transmissions and requests. Configuring the no form of the command may not prevent telco line providers from looping your router in esf mode, because fractional T1/T1 lines use facilities data link messages to initiate loopbacks.
If you enable the service-module t1 remote-loopback command, the loopback remote commands on the FT1/T1 CSU/DSU module will not be successful.
The following example displays two routers connected back-to-back through a fractional T1/T1 line:
Router# no service-module t1 remote-loopback full Router# service-module t1 remote-loopback payload alternate Router# loopback remote full %SERVICE_MODULE-5-LOOPUPFAILED: Unit 0 - Loopup of remote unit failed Router# service-module t1 remote-loopback payload v54 Router# loopback remote payload %SERVICE_MODULE-5-LOOPUPFAILED: Unit 0 - Loopup of remote unit failed Router# service-module t1 remote-loopback payload alternate Router# loopback remote payload %SERVICE_MODULE-5-LOOPUPREMOTE: Unit 0 - Remote unit placed in loopback
You can use the master indexes or search online to find documentation of related commands.
loopback remote (interface)
To define timeslots that constitute a fractional T1/T1 (FT1/T1) channel, use the service-module t1 timeslots interface configuration command. Use the no form of this command to resume the default setting (all FT1/T1 timeslots transmit at 64 kbps).
service-module t1 timeslots {range | all} [speed {56 | 64}]
range | The DS0 timeslots that constitute the FT1/T1 channel. The range is from 1 to 24, where the first timeslot is numbered 1 and the last timeslot is numbered 24. Specify this field by using a series of subranges separated by commas. |
all | Selects all FT1/T1 timeslots. |
speed | (Optional) Specifies the timeslot speed. |
56 | 56 kbps. |
64 | 64 kbps. This is the default for all timeslots. |
64 kbps
Interface configuration
This command first appeared in Cisco IOS Release 11.2.
This command specifies which timeslots are used in fractional T1 operation and determines the amount of bandwidth available to the router in each FT1/T1 channel.
The timeslot range must match the timeslots assigned to the channel group. Your service provider defines the timeslots that comprise a channel group.
To use the entire T1 line, enable the service-module t1 timeslots all command.
The following example displays a series of timeslot ranges and a speed of 64 kbps:
service-module t1 timeslots 1-10,15-20,22 speed 64
You can use the master indexes or search online to find documentation of related commands.
service-module t1 data-coding
service-module t1 linecode
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