3Com Router User Manual

							CT1/PRI Interface137
■The rules for address translation or packet filtering need to be set if the firewall 
is to be set up on the interface.
For more details, refer to the related sections of this manual.
3Bind an interface to be a pri set
Perform the following configurations in CT1/PRI interface view.
Ta b l e 140   Bind the interface to be a pri set
Timeslots on a CT1/PRI interface can be bound to be only one pri set.
When binding an interface to be a pri set, timeslot 24 is used as the D channel and 
the other timeslots are used as B channels. If no timeslots are specified to be 
bound, all the timeslots will be bound to form an interface similar to an ISDN PRI 
interface of 23B+D. If only timeslot 24 on the CT1/PRI interface is bound, the 
binding activity will fail.
Only one timeslot binding mode is supported on one CT1/PRI interface at one 
time, that is, the interface can only be bound into either channel sets or a pri set.
After the interface is bound to be a pri set, the system will automatically create a 
Serial interface numbered serial number:23. This interface is logically equivalent 
to an ISDN PRI interface, and hence you can further configure it.
Perform the following configuration in all views.
Ta b l e 141   Enter the ISDN interface view
The following is to be set:
■BDR operating parameters
■Encapsulate the data link layer protocol PPP, its authentication parameters and 
etc.
■IP address
■The operating parameters of the standby center need to be set when the 
interface serves as the main interface or standby interface of the standby 
center.
■Configure the firewall if necessary.
For more details, refer to the related sections of this manual.
4Set the length/attenuation of the transmission cable
When the CT1/PRI interface connects the transmission cables of different lengths, 
to ensure the quality of the signal to be received by the receiving end, the 
attenuation and waveform of signal should match the transmission cables.
Perform the following configurations in CT1/PRI interface view.
Ta b l e 142   Set the length/attenuation of the transmission cable of CT1/PRI interface
OperationCommand
Bind the timeslots of CT1/PRI interface to be a 
pri setpri-set [ timeslot-list range 
]
Remove binding timeslots to be a pri setundo pri-set
OperationCommand
Enter the ISDN interface viewinterface serial number:23
OperationCommand 
						

							138CHAPTER 10: CONFIGURING WAN INTERFACE
By default, the attenuation of transmission cable that the CT1/PRI interface 
matches is long 0db.
5Set the line code format
A CT1/PRI interface supports two types of line code formats: ami format and b8zs 
format.
Perform the following configurations in CT1/PRI interface view.
Ta b l e 143   Set the line code format on the CT1/PRI interface
By default, the line code format on the CT1/PRI interface is b8zs.
6Set line clock
When the CT1/PRI interface operates as DCE, you should choose the internal 
clock, that is, master clock mode. When it operates as DTE, you should choose 
the line clock, that is, slave clock mode.
When the CT1/PRI interfaces on two routers are directly connected, the two ends 
will respectively operate in line clock mode (slave) and internal clock mode 
(master). When the CT1/PRI interfaces on routers are connected to a switch, the 
switch will operate as DCE which provides clock signal, the interfaces on the 
routers will operate in line clock mode (slave).
Perform the following configurations in CT1/PRI interface view.
Ta b l e 144   Set the line clock of the CT1/PRI interface
By default, the line clock of CT1/PRI interface is slave clock.
7Set the frame format of interface
A CT1/PRI interface supports two frame formats: Super Frame (SF) and Extended 
Super Frame (ESF). In SF format, multiple frames can share the same 
frame-synchronization information and signaling information, so that more 
significant bits can be used to transmit user data. In practice, a system should be 
tested often. The application of ESF satisfies the requirement that the services are 
still in normal operation even at the time of testing.
Perform the following configurations in CT1/PRI interface view.
Ta b l e 145   Set the frame format of CT1/PRI interface
Set the CT1/PRI interface to use long-distance 
transmission cablecable long { 0db | -7.5db | 
-15db | -22.5db }
Set the CT1/PRI interface to use short-distance 
transmission cablecable short { 133ft | 266ft | 
399ft | 533ft | 655ft }
Restore the default value of the transmission 
cable used by the CT1/PRI interfaceundo cable
OperationCommand
Set the line code format on the CT1/PRI 
interfacecode { ami | b8zs }
Restore the line code format on the CT1/PRI 
interfaceundo code
OperationCommand
Set the line clock of the CT1/PRI interface clock { master | slave }
Restore the line clock of the CT1/PRI interface 
to the default valeundo clock
OperationCommand 
						

							E1-F Interface139
By default, the frame format of CT1/PRI interface is ESF.
8Enable/disable internal loopback/external loopback
The interface needs to be set to internal loopback or external loopback when 
during the test on some special functions.
Perform the following configurations in CT1/PRI interface view.
Ta b l e 146   Enable/disable the internal loopback/external loopback of the CT1/PRI
By default, the functions of internal loopback and external loopback are disabled 
on the CT1/PRI interfaces.
Display and Debug 
CT1/PRI InterfacePerform the following configurations in all views to display the status and related 
information of the CT1/PRI interface, so as to monitor and maintain it.
Ta b l e 147   Display and debug CT1/PRI interface
Generally, CT1/PRI interfaces are applied to the dedicated line and dial-up services. 
For the typical configuration example and troubleshooting, refer to the 
configurations of protocols at each layer and dialing configurations in this manual.
E1-F InterfaceE1-F interface is fractional E1 interface, and it is respectively simplified CE1/PRI 
interface. If there is no need to use multiple channel sets or if ISDN PRI is not 
necessary in an E1 application, it is too much to use CE1/PRI interface. At this time, 
E1-F interface is more than enough for meeting the simple E1 access 
requirements. Compared with CE1/PRI interface, E1-F interface is a nice low-cost 
choice for E1 access.
Compared with CE1/PRI interfaces, E1-F interface has the following features:
■When working in framed mode, E1-F interface can only bind time slots into 
one channel set, but CE1/PRI interface can group timeslots randomly and bind 
them into multiple channel sets.
■E1-F interface does not support PRI operating mode.
E1-F interface can work in both framed and unframed modes.
When it works in unframed mode, it is a timeslot-less interface of 2048kbps data 
bandwidth. In this case, it is logically equivalent to a synchronous serial interface, 
Set the frame format of CT1/PRI interface frame-format { sf | esf }
Restore the frame format of CT1/PRI interface 
to the default valueundo frame-format
OperationCommand
Enable the internal loopback/external loopback of the 
CT1/PRIloopback { remote | local }
Disable the internal loopback/external loopback of the 
CT1/PRIundo loopback { remote | 
local }
OperationCommand
Display the operating status of the CT1/PRI 
interfacedisplay controller t1 
interface-number
Display the operating status of the channel set 
or pri setdisplay interfaces serial 
interface-number:number 
						

							140CHAPTER 10: CONFIGURING WAN INTERFACE
supporting the data link layer protocols PPP, HDLC, Frame Relay, LAPB and X.25, as 
well as the network protocols IP and IPX.
When it works in framed mode, however, it is physically divided into 32 time slots 
numbered in the range of 0 to 31. In these time slots, except for time slot 0 used 
for synchronization information transmission, all the other time slots can be 
randomly bound into one channel set. E1-F interface has the rate of nx64kbps, 
owns logical features of synchronous serial interface, and supports the data link 
layer protocols PPP, Frame Relay, LAPB and X.25 as well as the network protocols IP 
and IPX.
Configure E1-F InterfaceE1-F interface configuration includes:
■Enter the view of a specified interface
■Set interface operating mode
■Set interface rate after binding operation
■Set line code format
■Set line clock
■Set interface frame format
■Enable or disable local/remote loopback
1Enter the view of a Specified Interface
Unlike CE1/PRI interface, E1-F interface has no Controller view. The system identify 
an E1-F interface as a synchronous serial interface, so entering the view of E1-F 
interface is equivalent to entering the view of the corresponding serial interface.
Perform the following configuration in all views.
Ta b l e 148   Enter the view of an E1-F interface
E1-F interface is sequenced based on the same numbering and are numbered 
together with the synchronous serial interfaces. For example, insert one 1E1-F 
module in slot 0 on a 3Com Router, and one 4SA module in slot 1. Hence, the 
E1-F interface will be numbered Serial 0, and the 4SA interfaces will be numbered 
Serial 1 through Serial 4.
2Set Interface Operating Mode
E1-F interface can work in both unframed and framed modes.
Perform the following configuration in E1-F interface view.
Ta b l e 149   Set Operating mode for an E1-F interface
By default, E1-F interfaces work in framed mode.
3Set Interface Rate after Binding Operation
When E1-F interface works in framed mode, time slot binding on the interfaces 
can be made according to users demands.
OperationCommand
Enter the view of an E1-F interfaceinterface serial serial-number
OperationCommand
Set an E1-F interface to work in unframed modefe1 unframed
Set the E1-F interface to work in framed modeundo fe1 unframed 
						

							E1-F Interface141
Perform the following configuration in E1-F interface view.
Ta b l e 150   Set interface rate after binding operation
By default, binding operation will be done on all the time slots on E1-F interface.
Time slot 0 on E1-F interface is used for synchronization information transmission. 
Therefore, in practice, only time slots 1 through 31 are bound when performing 
binding operation on all the time slots on an E1-F interface.
Unlike CE1/PRI interface, only one channel set can be bound on an E1-F interface, 
and this channel set is associated with the current synchronous serial interface. On 
a CE1/PRI interface, however, multiple channel sets can be bound, and the system 
will automatically generate a synchronous serial interface accordingly whenever a 
channel set is formed.
4Set Line Code Format
E1-F interfaces support line code formats AMI (Alternate Mark Inversion) and 
HDB3 (High Density Bipolar 3).
Perform the following configuration in E1-F interface view.
Ta b l e 151   Set line code format for E1-F interfaces
The line code format for an E1-F interface defaults to hdb3.
5Set Line Clock
If E1-F interface is used as DCE, the slave clock should be selected. If it is used as 
DTE, the master clock should be selected. 
If the E1-F interfaces of two routers are directly connected, they must respectively 
work in slave and master clock modes. If the E1-F interface of the router is 
connected to an exchange, however, the exchange is working as DCE and 
provides clock, so the interface of the router should work in master clock mode. 
Perform the following configuration in E1-F interface view.
Ta b l e 152   Set line clock for an E1-F interface
By default, the clock of E1-F interface is slave clock.
6Set Interface Frame Format
When an E1-F interface is working in framed mode, it supports both CRC4 (4-bit 
Cyclic Redundant Check) and no-CRC4 frame formats. 
Perform the following configuration in E1-F interface view.
OperationCommand
Bind time slots on an E1-F interfacefe1 timeslot-list { all | range }
Restore the default setting for time slot 
binding on the interfaceundo fe1 timeslots
OperationCommand
Set line code format for an E1-F interfacefe1 code { ami | hdb3 }
Restore the default line code format for an E1-F interfaceundo fe1 code
OperationCommand
Set line clock for an E1-F interfacefe1 clock { master | slave }
Restore the line clock of the E1-F interface to the 
default settingundo fe1 clock 
						

							142CHAPTER 10: CONFIGURING WAN INTERFACE
Ta b l e 153   Set frame format for an E1-F interface
By default, the frame format of E1-F interface is no-CRC4.
7Enable or Disable Local Loopback/Remote Loopback
An interface should be place in local loopback or remote loopback for some 
special functionality tests.
Perform the following configuration in E1-F interface view.
Ta b l e 154   Enable/Disable local/remote loopback on an E1-F interface
By default, no E1-F interface is placed in local or remote loopback.
On an interface, using this command but with different arguments can 
respectively enable local loopback and remote loopback, but these two functions 
cannot be enabled at the same time.
Display and Debug E1-F 
InterfacePerform the display command in all views to display the state of E1-F interface 
and other related information.
Ta b l e 155   Display and debug E1-F interface
OperationCommand
Set frame format for an E1-F interfacefe1 frame-format { crc4 | 
no-crc4 }
Restore the default frame format of the E1-F 
interfaceundo fe1 frame-format
OperationCommand
Enable local/remote loopback on an interfacefe1 loopback { local | remote }
Disable local/remote loopback on an interfaceundo fe1 loopback [ local | 
remote ]
OperationCommand
Display configuration and state of E1-F interfacedisplay fe1 [ serial 
serial-number ]
Display the operating state of E1-F interfacedisplay serial serial-number 
						

							T1-F Interface143
T1-F InterfaceT1-F interface is fractional T1 interface, and it is respectively simplified CT1/PRI 
interface. If there is no need to use multiple channel sets or if ISDN PRI is not 
necessary in an T1 application, it is too much to use CT1/PRI interface. At this time, 
T1-F interface is more than enough for meeting the simple T1 access 
requirements. Compared with CT1/PRI interface, T1-F interfaces is a nice low-cost 
choice for T1 access.
Compared with CT1/PRI interface, T1-F interface has the following features:
■When working in framed mode, T1-F interface can only bind time slots into 
one channel set, but CT1/PRI interface can group timeslots randomly and bind 
them into multiple channel sets.
■T1-F interface does not support PRI operating mode.
T1 line comprises 24 multiplexed channels. That is, a T1 primary group frame DS1 
(Digital Signal Level-1) comprises 24 DS0 (64kbps) time slots, each has 8 bits and 1 
framing bit for synchronization, and thus each primary group frame has 193 bits 
(24 X 8+1). As DS1 can transmit 8000 frames per second, its transmission speed is 
193 X 8k = 1544kbps.
T1-F interface can only work in framed mode, and it can randomly bind all time 
slots (time slots 1 through 24) into one channel set. T1-F interface has the rate of 
nx64kbps or nx56kbps, owns logical features of synchronous serial interface, and 
supports the data link layer protocols PPP, HDLC, Frame Relay, LAPB and X.25 as 
well as the network protocols IP and IPX.
Configure T1-F InterfaceT1-F interface configuration includes:
■Enter the view of a specified interface
■Set interface rate after binding operation
■Set length/attenuation of transmission line
■Set line code format
■Set line clock
■Set interface frame format
■Enable or disable local/remote loopback
1Enter the view of a Specified Interface
Unlike CT1/PRI interface, T1-F interface has no Controller view. The system identify 
a T1-F interface as a synchronous serial interface, so entering the view of T1-F 
interface is equivalent to entering the view of the corresponding serial interface.
Perform the following configuration in all views.
Ta b l e 156   Enter the view of an T1-F interface
T1-F interface is sequenced based on the same numbering and are numbered 
together with the synchronous serial interfaces. For example, insert one 1E1-F 
module in slot 0 on a 3Com Router, one 4SA module in slot 1, and two 1T1-F 
OperationCommand
Enter the view of a T1-F interfaceinterface serial 
serial-number 
						

							144CHAPTER 10: CONFIGURING WAN INTERFACE
module in slot 2. Hence, the E1-F interface will be numbered Serial 0, and the 4SA 
interfaces will be numbered Serial 1 through Serial 4, and the T1-F interfaces will 
be numbered Serial 5 and Serial 6.
2Set Interface Rate after Binding Operation
When T1-F interface works in framed mode, time slot binding on the interfaces 
can be made according to users demands.
Perform the following configuration in T1-F interface view.
Ta b l e 157   Set interface rate after binding operation
By default, binding operation will be done on all the time slots on T1-F interface.
Unlike CT1/PRI interface, only one channel set can be bound on a T1/F interface, 
and this channel set is associated with the current synchronous serial interface. On 
a CT1/PRI interface, however, multiple channel sets can be bound, and the system 
will automatically generate a synchronous serial interface accordingly whenever a 
channel set is formed.
3Set Length/Attenuation for Transmission Line
If a T1-F interface is connected to the transmission lines of various lengths, you 
should match attenuation and waveform of the interface signals with the 
transmission lines.
Perform the following configuration in T1-F interface view.
Ta b l e 158   Set length/attenuation of transmission line on a T1-F interface
By default, attenuation matched a T1-F interface is long 0db.
4Set Line Code Format
T1-F interface supports line code formats AMI (Alternate Mark Inversion) and B8ZS 
(Bipolar 8-Zero Substitution).
Perform the following configuration in T1-F interface view.
Ta b l e 159   Set line code format for T1-F interface
The line code format for an T1-F interface defaults to b8zs.
5Set Line Clock
OperationCommand
Bind time slots on a T1-F interfaceft1 timeslot-list { all | 
range } [ speed { 56 | 64 } ]
Restore the default setting for time slot binding on 
the interfaceundo ft1 timeslots
OperationCommand
Set the T1-F interface to use long-distance transmission 
lineft1 cable long decibel
Set the T1-F interface to use short-distance transmission 
lineft1 cable short length
Restore the default setting of the transmission line for 
the T1-F interfaceundo ft1 cable
OperationCommand
Set line code format for a T1-F interfaceft1 code { ami | b8zs }
Restore the default line code format for a T1-F interfaceundo ft1 code 
						

							T1-F Interface145
If T1-F interface is used as DCE, the slave clock should be selected. If it is used as 
DTE, the master clock should be selected. 
If the T1-F interfaces of two routers are directly connected, they must respectively 
work in slave and master clock modes. If the T1-F interface of the router is 
connected to an exchange, however, the exchange is working as DCE and 
provides clock, so the interface of the router should work in master clock mode. 
Perform the following configuration in T1-F interface view.
Ta b l e 160   Set line clock for a T1-F interface
By default, the clock of T1-F interface is slave clock.
6Set Interface Frame Format
T1-F interfaces support Supper Frame (SF) and Extended Supper Frame (ESF). In SF, 
multiple frames can share the same frame synchronization and signaling 
information, so that more significant bits can be used for transmitting user data. In 
practice, the system test is often required. The application of ESF technology can 
ensure normal service when the system test is being carried out.
Perform the following configuration in T1-F interface view.
Ta b l e 161   Set frame format of T1-F interface
By default, the frame format of T1-F interface is ESF.
7Enable or Disable Local Loopback/Remote Loopback
An interface should be place in local loopback or remote loopback for some 
special functionality tests.
Perform the following configuration in T1-F interface view.
Ta b l e 162   Enable/Disable local/remote loopback on a T1-F interface
By default, no T1-F interface is placed in local or remote loopback.
On an interface, using this command but with different arguments can 
respectively enable local loopback and remote loopback, but these two functions 
cannot be enabled at the same time.
OperationCommand
Set line clock for a T1-F interfaceft1 clock { master | 
slave }
Restore the line clock of the T1-F interface to the default 
settingundo ft1 clock
OperationCommand
Set frame format for a T1-F interfaceft1 frame-format { sf | 
esf }
Restore the default frame format of T1-F interfaceundo ft1 frame-format
OperationCommand
Enable local/remote loopback on an interfaceft1 loopback { local | 
remote }
Disable local/remote loopback on an interfaceundo ft1 loopback [ 
local | remote ] 
						

							146CHAPTER 10: CONFIGURING WAN INTERFACE
Display and Debug T1-F 
InterfacePerform the display command in all views to display the state of T1-F interface 
and other related information.
Ta b l e 163   Display and debug T1-F interface
CE3 InterfaceBoth E3 and E1 belong to ITU-T digital carrier system and are used in most areas 
outside the North America. The data transmission rate of E3 interface is 
34.368Mbps, and the line coding/decoding is HDB3 (High-Density Bipolar 3). 
CE3 interface has two operating modes:
■When working in E3 mode, the interface is equivalent to a fractional interface 
of data bandwidth 34.368Mbps.
■When working in CE3 mode, the interface can multiplex/demultiplex 16 
channels of E1 signals. E3-to-E1 multiplex is compliant with ITU-T G.751 and 
G.742. Each E1 interface can be divided into 32 time slots numbered in the 
range of 0 to 31. The time slots between 1 and 31 can be randomly bound into 
N x 64Kbps logical channels (time slot 0 for transmitting frame synchronizing 
signals cannot participate in binding operation). Therefore, CE3 interface can 
be channelized into E1 channels of 64Kbps.
CE3 interface supports the link layer protocols PPP, HDLC, Frame Relay, LAPB and 
X.25, and the network protocols such as IP and IPX.
Configure CE3 InterfaceCE3 interface configuration includes:
■Enter the view of the specified CE3 interface
■Set clock mode for the CE3 interface
■Set national bit for the CE3 interface
■Set the loopback mode of the CE3 interface
■Set E1 Frame format
■Set operating mode of CE3 interface
Depending on the networking requirements, you may need to configure the 
parameters such as PPP, Frame Relay and IP address for the CE3 interface. For 
details, refer to the involving chapters.
1Enter view of Specified Interface for Configuration
CE3 interface uses the controller command to enter its view.
Perform the following configuration in system view to enter the view of the 
specified CE3 interface.
OperationCommand
Display configuration and state of T1-F interfacedisplay ft1 [ serial 
serial-number ]
Display the operating state of T1-F interfacedisplay serial 
serial-number