3Com Router User Manual

Synchronous Serial Interface127
Level detection is enabled for the synchronous serial interface by default.
9Enable or disable data carrier detection
By default, when the system decides whether the synchronous serial interface is in 
UP status or DOWN status, it detects the DSR signal, DCD signal and whether the 
interface connects a cable at the same time. Only when the three signals are 
effective, will the system regard the interface is in UP status, otherwise, in DOWN 
status. If data carrier...

128CHAPTER 10: CONFIGURING WAN INTERFACE
12Configure MTU
MTU of synchronous serial interface affects the fragmentation and reassembling 
of IP network protocol message on this interface.
Please use the following commands in the view of the synchronous serial 
interface.
Ta b l e 121   Set MTU of synchronous serial interface
The unit of mtu is byte, ranging between 128-1500, with 1500 as default.
13Configure the time interval for sending keepalive packets
The serial interface will send keepalive packets...

ISDN BRI Interface129
equipment complying with relevant ISDN standard of ITU-T able to access ISDN 
easily.
User-network interface specification of ISDN:
In ITU-T I.411 recommendations, reference configurations for ISDN user-network 
interfaces are given according to concepts of function group (a group of functions 
required by users to access ISDN) and reference point (a point used to distinguish 
function groups), as shown in the following diagram.
Figure 47   Reference configuration of ISDN...

130CHAPTER 10: CONFIGURING WAN INTERFACE
■Whether the interface provided by telecom service provider is ISDN BRI U 
interface or ISDN BRI S/T interface: In ITU-T I.411 recommendation, the 
reference model of ISDN user-network interface is given. However, there is a 
worldwide dispute about the position of division point between the user and 
network. And U interface or S/T interface is used according to different nations. 
In this case, before purchasing the router, the user must ensure whether the...

CE1/PRI Interface131
■When the interface is used as a CE1 interface, all the timeslots except timeslot 
0 can be divided into multiple channel sets at will, and each group can be used 
as an interface upon timeslot binding. Its logic feature is the same as that of a 
synchronous serial interface. It supports the data link layer protocols, such as 
PPP, Frame Relay, LAPB and X.25, and the network protocols such as IP and IPX.
■When the interface is used as a PRI interface, timeslot 16 will be used as a D...

132CHAPTER 10: CONFIGURING WAN INTERFACE
Ta b l e 127   Enter the synchronous serial interface view
The following are to be set:
■Operating parameters of data link layer protocol, such as PPP, Frame Relay, 
LAPB or X.25.
■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. 
■The rules for address translation or packet filtering need to be set if the firewall 
is to be set up on the...

CE1/PRI Interface133
■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.
4Bind an interface to be a pri set
Perform the following configurations in CE1/PRI interface view.
Ta b l e 130   Bind the interface to be a pri set
Timeslots on a CE1/PRI interface can be bound to be only one pri set.
When binding an interface to be a pri set, timeslot 16 on a CE1/PRI interface is...

134CHAPTER 10: CONFIGURING WAN INTERFACE
Ta b l e 132   Set the line code format on the CE1/PRI interface
By default, the line code format on the CE1/PRI interface is hdb3.
6Set line clock
When the CE1/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 CE1/PRI interfaces on two routers are directly connected, the two ends 
will respectively operate in line clock...

CT1/PRI Interface135
By default, the functions of internal loopback and external loopback are disabled 
on the CE1/PRI interface.
Display and Debug 
CE1/PRI InterfacePerform the following configurations in all views to display the status and related 
information of the CE1/PRI interface, so as to monitor and maintain it.
Ta b l e 136   Display and debug CE1/PRI interface
Generally, CE1/PRI interface is applied to the dedicated line and dial-up services. 
For the typical configuration example and...

136CHAPTER 10: CONFIGURING WAN INTERFACE
■Bind the interface to be a pri set
■Set the length/attenuation of the transmission cable
■Set the line code format
■Set line clock
■Set frame format
■Enable/disable internal loopback/external loopback
1Enter the view for a specified interface
In system view, use the following command to enter the view of a specified 
CT1/PRI interface.
Ta b l e 137   Enter the view of a specified interface
2Bind the interface to be channel sets
Perform the following...