3Com Router User Manual

							CE3 Interface147
Ta b l e 164   Enter the view of the specified E3 interface
2Set Clock Mode of CE3 Interface
Perform the following configuration in CE3 interface view.
Ta b l e 165   Set clock mode of the CE3 interface
By default, CE3 interface uses slave clock.
The user can also set clock mode for E1 channels of CE3 interface.
Ta b l e 166   Set clock mode of the E1 channel
By default, E1 channel uses slave clock.
3Set National Bit for CE3 Interface
Perform the following configuration in CE3 interface view.
Ta b l e 167   Set a national bit of the CE3 interface
By default, national bit of CE3 interface is 1.
4Set the Loopback Mode of CE3 Interface
Perform the following configuration in CE3 interface view.
Ta b l e 168   Set loopback mode of CE3 interface
By default, loopback is disabled.
Single-channel loopback can be set on the E1 channels on a CE3 interface, and 
the settings of individual channels are independent.
Ta b l e 169   Set loopback mode of E1 channel
5Set E1 Frame Format
OperationCommand
Enter the view of CE3 interfacecontroller e3 number
OperationCommand
Set clock mode of the CE3 interfaceclock { master | slave }
Restore the default clock mode of CE3 interfaceundo clock
OperationCommand
Set clock mode of the E1 channele1 line-number set clock { 
master | slave }
Restore the default clock mode of E1 channelundo e1 line-number set 
clock
OperationCommand
Set national bit of the CE3 interfacenational-bit { 0 | 1 }
Restore the default national bitundo national-bit
OperationCommand
Set loopback mode of CE3 interfaceloopback { local | payload | 
remote }
Disable loopback on the CE3 interfaceundo loopback
OperationCommand
Set loopback mode of E1 channele1 line-number set loopback 
{ local | remote }
Disable loopback on the E1 channelundo e1 line-number set 
loopback 
						

							148CHAPTER 10: CONFIGURING WAN INTERFACE
If framing has been enabled on an E1 channel, you can set its frame format. 
Perform the following configuration in CE3 interface view.
Ta b l e 170   Set E1 frame format
By default, the frame format of E1 channel is no-crc4.
6Configure Operating Mode of CE3 Interface
When setting the operating mode of an CE3 interface, you should set the 
operating modes of both the CE3 interface and the E1 channels on the interface.
Perform the following configuration in CE3 interface view.
Ta b l e 171   Set the operating mode of CE3 interface
By default, CE3 mode is used. 
When CE3 interface works in E3 mode, the system will automatically create a 
serial interface whose number is serial number/0:0 and whose rate is 34.368 
Mbps. The interface has the same logic feature as that of a synchronous serial 
interface, therefore, it can be regarded as a synchronous serial interface for further 
configuration.
Ta b l e 172   Set the operating mode of E1 channel
The operation mode of E1 channels defaults to CE1 mode.
When E1 channel works in E1 mode (unframed mode), the system will 
automatically create a serial interface whose number is serial number / 
line-number:0 and whose rate is 2048 kbps. The interface has the same logic 
feature as that of a synchronous serial interface, therefore, it can be regarded as a 
synchronous serial interface for further configuration.
When E1 channel works in CE1 mode (framed mode), timeslot binding can be 
performed on it. The system will automatically create a serial interface whose 
number is serial number / line-number:set-number and whose rate is N x 64 kbps. 
The interface has the same logic feature as that of a synchronous serial interface, 
therefore, it can be regarded as a synchronous serial interface for further 
configuration.
OperationCommand
Set E1 frame formate1 line-number set frame-format { 
crc4 | no-crc4 }
Restore the default CRC settingundo e1 line-number set 
frame-format
OperationCommand
Enable E3 modeusing e3
Enable CE3 modeusing ce3
Restore the default operating modeundo using 
OperationCommand
Configure E1 channels of CE3 interface to 
work in E1 mode (unframed mode)e1 line-number unframed
Configure E1 channels of CE3 interface to 
work in CE1 mode (framed mode)undo e1 line-number unframed
Implement time slot binding on the CE1 
interfacee1 line-number channel-set 
set-number timeslot-list range
Disable time slot binding on the CE1 interface undo e1 line-number channel-set 
set-number 
						

							CT3 Interface149
Display and Debug CE3 
InterfaceThe display and debug operations of CE3 interface include disabling interface and 
displaying interface information. But you should be careful when using the 
shutdown command, because disabling an interface will cause the interface to 
stop working.
Perform the following configuration in all views.
Ta b l e 173   Display and debug CE3 interface
The enabling/disabling operation done on the CE3 interface takes effect on CE3 
interface, the demultiplexed E1 channels and the serial interfaces formed through 
binding operation. The enabling/disabling operation done on the E1 interface 
takes effect on E1 interface and the serial interfaces formed through binding 
operation. After executing the 
shutdown command on the specified CE3 interface, 
all the E1 channels and the serial interfaces formed by channel binding on the CE3 
interface will be shut down, and data transmitting and receiving activities will 
stop. Executing the 
undo shutdown command, however, will re-enable all the E1 
channels and the serial interfaces formed by channel binding operations.
CT3 InterfaceBoth T3 and T1 belong to the T-carrier system specified by ANSI, T3 is 
corresponding to the digital signal level DS-3, and the data transmission rate is 
44.736Mbps.
CT3 interface has two operating modes: T3 mode (channelized mode) and CT3 
mode (non-channelized mode).
■When working in T3 mode, the interface is equivalent to a fractional interface 
of data bandwidth 44736kbps.
■When working in CT3 mode, the interface can multiplex/demultiplex 28 
channels of T1 signals. Each T1 interface can be divided into 24 time slots 
numbered in the range of 1 to 24. These time slots can be randomly bound 
into N x 64Kbps or N x 56Kbps logical channels.
CT3 interface supports the link layer protocols PPP, HDLC, Frame Relay, LAPB and 
X.25, and the network protocols such as IP and IPX.
Configure CT3 InterfaceCT3 interface configuration includes:
■Enter the view of the specified CT3 interface
■Set clock mode
■Set cable length
■Set loopback mode
■Set frame format
■Set operating mode of CT3 interface
OperationCommand
Disable the CE3 interfaceshutdown
Enable the CE3 interfaceundo shutdown
Disable the E1 channele1 line-number shutdown
Enable the E1 channelundo e1 line-number shutdown
Display the CE3 interface informationdisplay controller e3 number 
						

							150CHAPTER 10: CONFIGURING WAN INTERFACE
■Set CRC of the Serial Interface
Depending on the networking requirements, the user perhaps needs to configure 
the parameters such as PPP, Frame Relay and IP address for the CT3 interface. For 
details, refer to the involving chapters.
1Enter the view of the specified CT3 interface
CT interface uses the controller command to enter its view.
Perform the following configuration in system view. 
Ta b l e 174   Enter specified CT3 interface view
2Set Clock Mode
CT3 Interface supports two clock modes:
■Master clock mode: to use internal clock signal
■Slave clock mode: to use line clock signal
Perform the following configuration in CT3 Interface view. 
Ta b l e 175   Set clock mode of the CT3 interface 
By default, CT3 interface uses slave clock.
The user can also set clock mode for T1 channels of CT3 interface.
Ta b l e 176   Set clock mode of the T1 channel
By default, T1 channel uses slave clock.
3Set Cable Length
Use the cable command to set the distance between the router and the cable 
distribution frame.
Perform the following configuration in CT3 interface view.
Ta b l e 177   Set cable length of the CT3 interface
By default, the cable length of the CT3 interface is set to 350 feet.
4Set Loopback Mode
The CT3 interface supports loopback test on data at the rate of DS-3. Do not 
enable the loopback function in normal operation.
Perform the following configuration in CT3 interface view.
OperationCommand
Enter specified CT3 Interface view controller t3 interface-number
OperationCommand
Set clock mode of the CT3 interfaceclock { master | slave }
Restore the default clock mode of CT3 interfaceundo clock
OperationCommand
Set clock mode of the T1 channelt1 line-number set clock { 
master | slave }
Restore the default clock mode of T1 channelundo t1 line-number set clock
OperationCommand
Set cable length of the CT3 interfacecable feet
Restore the default cable lengthundo cable 
						

							CT3 Interface151
Ta b l e 178   Set loopback mode of the CT3 interface 
Difference between two types of external loopback of the CT3 interface: Frame 
header overhead should be processed for external payload loopback (payload) 
while frame is not processed for external remote loopback (remote). 
By default, loopback is disabled.
Single-channel loopback can be set on the T1 channels on a CT3 interface, and 
the settings of individual channels are independent.
Ta b l e 179   Set loopback mode of T1 channel
By default, loopback is disabled.
5Set Frame Format
Two frame formats are used on CT3 interface: M23 and C-bit.
Perform the following configuration in CT3 interface view.
Ta b l e 180   Set frame format of the CT3 interface
By default, the CT3 interface uses the C-bit frame format.
When CT3 interface work in CT3 mode, single-channel frame format can be set 
on the T1 channels, and the settings of individual channels are independent.
Perform the following configurations in CT3 interface view.
Ta b l e 181   Set the frame format of T1 channel
By default, the frame format of T1 channel is ESF.
6Configure Operate Mode of CT3 Interface
When setting the operating mode of a CT3 interface, you should set the operating 
modes of both the CT3 interface and the T1 channels on the interface.
Perform the following configuration in CT3 interface view.
Ta b l e 182   Set the operating mode of CT3 interface
OperationCommand
Set loopback mode of CT3 interfaceloopback { local | payload | 
remote }
Disable loopback on the CT3 interfaceundo loopback
OperationCommand
Set loopback mode of T1 channelt1 line-number set loopback { local 
| remote }
Disable loopback on the T1 channelundo t1 line-number set loopback
OperationCommand
Set CT3 frame formatframe-format { c-bit | m23 }
Restore the default settingundo frame-format
OperationCommand
Set the frame format of T1 channelframe-format { sf | esf }
Restore the frame format of T1 channel to the 
default valueundo frame-format
OperationCommand
Configure Operate Mode of CT3 Interfaceusing { t3 | ct3 }
Restore Operate Mode of CT3 Interface to defaultundo using 
						

							152CHAPTER 10: CONFIGURING WAN INTERFACE
By default, CT3 mode is used. 
When CT3 interface works in T3 mode, the system will automatically create a 
serial interface whose number is serial number/0:0 and whose rate is 
44.736Mbps. The interface has the same logic feature as that of a synchronous 
serial interface; therefore, it can be regarded as a synchronous serial interface for 
further configuration.
Ta b l e 183   Set the operating mode of T1 channel
The operation mode of T1 channels defaults to CT1 mode.
When T1 channel works in T1 mode (unframed mode), the system will 
automatically create a serial interface whose number is serial number / 
line-number:0 and whose rate is 1544kbps. The interface has the same logic 
feature as that of a synchronous serial interface; therefore, it can be regarded as a 
synchronous serial interface for further configuration.
When T1 channel works in CT1 mode (framed mode), timeslot binding can be 
performed on it. The system will automatically create a serial interface whose 
number is serial number / line-number: set-number and whose rate is N x 64 kbps 
or N x 56 kbps. The interface has the same logic feature as that of a synchronous 
serial interface; therefore, it can be regarded as a synchronous serial interface for 
further configuration.
7Set CRC of the Serial Interface
For the serial interface formed by T3, the one formed by T1 channel or the one 
bundled by T1 channel timeslots, its CRC can be configured in the corresponding 
serial interface view.
Ta b l e 184   Set CRC of the serial interface
By default, the serial interface uses 16-bit CRC.
Display and Debug CT3 
InterfaceThe display and debug operations of CT3 interface include disabling interface and 
displaying interface information. But you should be careful when using the 
shutdown command, because disabling an interface will cause the interface to 
stop working.
Perform the following configuration in CT3 interface view.
OperationCommand
Configure T1 channels of CT3 interface to work 
in T1 mode (unframed mode)t1 line-number unframed
Configure T1 channels of CT3 interface to work 
in CT1 mode (framed mode)undo t1 line-number unframed
Implement time slot binding on the CT1 interfacet1 line-number channel-set 
set-number timeslot-list range 
[ speed { 56 | 64 } ]
Disable time slot binding on the CT1 interface undo t1 line-number channel-set 
set-number
OperationCommand
Set CRC of the Serial Interfacecrc { 16 | 32 | none }
Restore CRC of the Serial Interface to default valueundo crc 
						

							CT3 Interface153
Ta b l e 185   Disable and Enable CT3 interface
The enabling/disabling operation done on the CT3 interface takes effect on CT3 
interface, the T1 channels and the serial interfaces formed through binding 
operation. The enabling/disabling operation done on the T1 interface takes effect 
on T1 interface and the serial interfaces formed through binding operation. 
To disable/enable only the serial interface formed by T3, the serial interface formed 
by T1 channel or the serial interface formed by timeslot bundle of T1 channel, user 
can use command 
shutdown/undo shutdown in Serial interface view.
Perform the following configuration in all views.
Ta b l e 186   Display and debug of the CT3 interface
OperationCommand
Disable CT3 Interfaceshutdown
Enable CT3 Interfaceundo shutdown
Disable T1 channelt1 t1-number shutdown
Enable T1 channelundo t1 t1-number shutdown
OperationCommand
Display the T3/CT3 Controller state and states of 
all channelsdisplay controller t3 [ 
interface-number ]
Display the configuration and state information 
of the serial interface formed by the T3/CT3 
interfacedisplay interface serial 
interface-number 
						

							154CHAPTER 10: CONFIGURING WAN INTERFACE 
						

							11
CONFIGURING LOGICAL INTERFACE
This chapter contains information on the following topics:
■Logical Interface Introduction
■Dialer Interface
■Loopback Interface
■Null Interface
■Sub-Interface
■Standby Center Logic Channel
■Virtual-Template and Virtual Interface
Logical Interface 
IntroductionThe logical interface refers to the interface that can exchange data, but does not 
exist physically and needs to be established through configuration, including the 
Dialer interface, loopback interface, null interface, sub-interface, standby center 
logic channel and virtual-template. 
Dialer InterfaceDialer interface is used for dialup. Dial-supporting interfaces on the 3Com Router 
series include synchronous serial interface, asynchronous serial interface, ISDN BRI 
interface and ISDN PRI interface. The 3Com Router realizes the Bandwidth on 
Demand Routing (BDR) function, and provides two BDR configuration methods: 
Legacy BDR and BDR profiles. Please see Operation Manual - Dial-up for detailed 
information.
Configure Dialer 
Interface According to different BDR modes, configurations of Dialer interface are:
■Configure Dialer interface for Legacy BDR
■Configure Dialer interface for BDR profiles
Please see related chapters in Operation Manual - Dial-up for detailed description, 
monitoring and maintenance, typical configuration example, fault diagnosis and 
troubleshooting of the configurations of BDR. 
Loopback InterfaceIt is prescribed in TCP/IP that the network segment 127.0.0.0 is loopback address. 
The interface with the loopback address is called loopback interface. The 3Com 
Router series define interface Loopback0 as the loopback interface, which can 
receive all the packets destined for this router. The addresses on the loopback 
interfaces can neither be configured nor be advertised by routing protocols. 
						

							156CHAPTER 11: CONFIGURING LOGICAL INTERFACE
Some applications (such as configuring local peer of SNA) requires that a local 
interface with specified IP address should be configured without affecting physical 
interface configuration. Furthermore, this address should have a 32-bit mask to 
reduce the use of IP addresses and it should be advertised by the routing 
protocols. Therefore, the loopback interface is added to meet this requirement.
Configure Loopback 
InterfaceLoopback interface configuration includes:
■Create the loopback interface
■Configure operating parameters of the interfacE
1Create loopback interface
Ta b l e 187   Create/delete loopback interface
2Configure operating parameters on the interface
The parameters such as IP address and IP routing can be configured on loopback 
interface. For detailed configuration, refer to Operation Manual – Network 
Protocol.
The 32-bit mask can be configured for the loopback interface, that is, the mask 
can be 255.255.255.255. The IP address with this 32-bit mask can be advertised 
by the routing protocols.
When configuring the ip address of loopback interface, it is recommended to 
configure the 32bit mask to save the ip address.
Null InterfaceThe 3Com Router support Null interface. Null interface is always in UP status, but 
cannot forward data packet or configure IP address or encapsulate other 
protocols. 
Null interface is a virtual interface. Any network data packet sent to this interface 
will be dropped.
Configure Null InterfaceNull interface configuration includes:
■Create the Null interface
■Configure operating parameters of the interface
1Create the Null interface
Only one interface Null 0 can be created on the 3Com Router. Please perform the 
following configurations in all views.
Ta b l e 188   Create/Delete Null interface:
OperationCommand
Create the loopback interface and enter loopback 
interface viewinterface loopback number
Delete the specified loopback interfaceundo interface loopback 
number
OperationCommand
Create the Null interface and enter Null interface viewinterface null 0
Delete the Null interfaceundo interface null 0