3Com Router User Manual

							Typical SLIP Configuration Example187
III. Configuration Procedure
1Configure Router A:
aConfigure Dialer Rule
[Router]dialer-rule 1 ip permit
bConfigure the synchronous/asynchronous interface to asynchronous mode
[Router]interface serial 0
[Router-Serial0]physical-mode async
cConfigure IP address of synchronous/asynchronous interface
[Router-Serial0]ip address 10.110.0.1 255.0.0.0
dConfigure the incoming and outgoing call authorities of Modem
[Router-Serial0]modem
eEnable BDR
[Router-Serial0]dialer enable-legacy
fConfigure the Dialer String to router B
[Router-Serial0]dialer number 8810026
gConfigure the link layer protocol of the interface to SLIP
[Router-Serial0]link-protocol slip
hSpecify Dialer Group
[Router-Serial0]dialer-group 1
iConfigure the default route to Route B
[Router]ip route-static 0.0.0.0  0.0.0.0  10.110.0.2
2Configure Router B:
aConfigure Dialer Rule
[Router]dialer-rule 1 ip permit
bConfigure the synchronous/asynchronous interface to asynchronous mode
[Router]interface serial 0
[Router-Serial0]physical-mode async
cConfigure IP address of synchronous/asynchronous interface
[Router-Serial0]ip address 10.110.0.2  255.0.0.0
dConfigure the incoming and outgoing call authorities of Modem
[Router-Serial0]modem
eEnable BDR
[Router-Serial0]dialer enable-legacy
fConfigure the Dialer Number to router A
[Router-Serial0]dialer number 8810003
gConfigure the link layer protocol of the interface to SLIP
[Router-Serial0]link-protocol slip
hSpecify Dialer Group
[Router-Serial0]dialer-group 1
iConfigure the default route to Route A 
						

							188CHAPTER 14: CONFIGURING SLIP
[Router]ip route-static 0.0.0.0   0.0.0.0   10.110.0.1 
						

							15
CONFIGURING ISDN PROTOCOL
This chapter contains information on the following topics:
■ISDN Overview
■Configure ISDN
■Display and Debug ISDN
■Typical Configuration Example
■Fault Diagnosis and Troubleshooting of ISDN
ISDN OverviewISDN (Integrated Services Digital Network), developed from telephone integrated 
digital network (IDN), provides end-to-end digital connection, so as to support 
wide range of services (including voice and non-voice services).
ISDN provides the user with a group of standard multifunctional user-network 
interfaces. In ITU-T I.412 recommendations, two types of user-network interfaces 
are specified: Basic Rate Interface (BRI) and Primary Rate Interface (PRI). The 
bandwidth of BRI is 2B+D, and that of PRI is 30B+D or 23B+D. Here:
■B channel is a user channel, used to transmit the voice, data and other user 
information with the transmission rate 64kbps.
■D channel is a control channel and used to transmit the common channel 
signaling, controlling the calls on B channels of the same interface. The rate of 
D channel is 64kbit/s (PRI) or 16kbps (BRI).ITU-T Q.921, the data link layer 
protocol of D channel, defines the rules by which the information is exchanged 
between layer-2 entities on the user-network interface through D channel. 
Meanwhile, it supports the access of layer-3 entity. ITU-T Q.931, the network 
layer protocol of D channel, provides methods to establish, maintain and 
terminate the network connection between communication application 
entities.
Figure 55   Protocol stack of ISDN D channel
Configure ISDNISDN configuration includes:
■Configure ISDN signaling type
■Configure QSIG signaling parameters
BRIPRI
Q.921 LAPD
Q.931QSIG
Layer 1 Layer 2 Layer 3 
						

							190CHAPTER 15: CONFIGURING ISDN PROTOCOL
■Set the called number or sub-address to be checked in digital incoming call
1Configure ISDN Signaling Type 
Perform the following configurations in either system view or interface view.
Ta b l e 220   Configure type of signaling on ISDN interface
By default, DSS1 signaling is used on ISDN PRI interfaces.
The isdn protocol-type command can take effect only on ISDN PRI interfaces. 
For an ISDN BRI interface, it does not take effect. In other words, an ISDN BRI 
interface can use only DSS1 signaling, whereas an ISDN PRI interface can use 
either DSS1 signaling or QSIG signaling. 
Using the isdn protocol-type command in system view will not affect the 
existing ISDN PRI interface, and it will only change the default type of signaling on 
the newly created ISDN PRI interface.
2Configure the QSIG Signaling Parameters
If QSIG signaling is used on an ISDN PRI interface, you can configure the QSIG 
signaling parameters.
 The following configuration commands can be used only 
when the ISDN PRI interface adopts QSIG signaling.
aLength of call reference
Call reference is the flag used to distinguish the communication entities. A call 
reference uniquely identifies a call.
Perform the following configurations in interface view.
Ta b l e 221   Configure the length of call reference
By default, the length of call reference is two bytes.
bMode in which a called number is received
A router can receive called numbers in two modes: overlap receiving and 
complete receiving.
 You can set the receiving mode on the router according to 
the transmitting mode on the peer.
Perform the following configurations in interface view.
Ta b l e 222   Configure the receiving mode
By default, ISDN PRI interfaces receive called numbers in overlap receiving 
mode.
cMode in which a called number is sent
OperationCommand
Set ISDN signaling to QSIGisdn protocol-type qsig
Set ISDN signaling to DSS1 (Digital Subscriber 
Signaling No.1)isdn protocol-type dss1-
OperationCommand
Set the length of call reference to 1 byteisdn crlength 1
Set the length of call reference to 2 bytesisdn crlength 2
OperationCommand
Overlap receiving mode is used.isdn overlap-receiving
Complete receiving mode is used.undo isdn overlap-receiving 
						

							Configure ISDN191
When a router originates a call to PBX, it usually contains all called number 
information in the SETUP message.
 However, you can configure the command 
to determine whether the Sending Sending-Complete Information Element 
(SCIE) should be carried in the SETUP message.
 
Perform the following configurations in interface view.
Ta b l e 223   Configure the sending mode
By default, when a router sends a number, the Sending-Complete Information 
Element is carried in the SETUP message.
dInterval of QSIG signaling timer
Perform the following configurations in interface view.
Ta b l e 224   Configure interval for QSIG signaling timer
You can configure the QSIG signaling timers, including T301, T302, T303, 
T304, T305, T308, T309, T310, T313, T316 and T322. Also, you can use the 
display isdn qsig-timer command to view the default values of all the 
QSIG signaling timers.
3Verify the called number in an ISDN incoming call
Whenever an ISDN called party receives an incoming call, it can verify the called 
number in the incoming call from the remote end. If the called number in the 
remote call differs from the local configuration, the call will be denied. Otherwise, 
the call will be accepted.
Perform the following configurations in interface view.
Ta b l e 225   Set the called number or sub-address to be checked in digital incoming call
By default, no called number or sub-address is configured.
The commands are used to set the items to be checked in the digital incoming call. 
If the sub-address is set, call of the opposite will be rejected when the sub-address 
is not sent or is sent incorrectly. 
OperationCommand
Enable the router to carry the Sending-Complete 
Information Element (SCIE) in the SETUP message 
when sending a numberisdn sending-complete
Disable the router to carry the Sending-Complete 
Information Element in the SETUP message when 
sending the numberundo isdn sending-complete
OperationCommand
Set interval for a QSIG signaling timerisdn qsig-timer timer-name 
time-interval
Restore the default interval value(s) of QSIG 
signaling timer(s)undo isdn qsig-timer { 
timer-name | all }
OperationCommand
Set the called number or sub-address to be 
checked in digital incoming callisdn check-called-number [ 
called-party ] [ :sub-address 
] 
Remove the called number or sub-address to 
be checked in digital incoming callundo isdn check-called-number 
						

							192CHAPTER 15: CONFIGURING ISDN PROTOCOL
Configure ISDN DoVISDN call includes voice call and digital call. Different communication mode makes 
different calls. In common circumstances, users initiate voice call when making 
voice communication and initiate digital call when making data transmission. ISDN 
DoV (Data over Voice) can firstly establish connections by voice call, and then 
begins data transmission. ISDN DoV can apply to such conditions as digital call is 
disabled (for example, long-distance call). However compared with digital call, 
ISDN DoV has some disadvantages. It cannot guarantee correct data transmission 
all the time and needs ISDN network support.
1Configure Calling Method for Initiating a Connection on an Interface
For an interface generating ISDN calls, you must set the call type to either voice 
call or data call.
Perform the following configuration in dialer interface or ISDN interface view.
Ta b l e 226   Configure an interface for voice calls
2Configure Call Processing Method on an Interface
On an interface receiving ISDN calls, you can configure it to process calls as either 
voice calls or data calls. Regardless of how it processes a call, however, the packets 
transmitted over the established connection are data packets.
Perform the following configuration in ISDN interface view.
Ta b l e 227   Configure an interface to receive voice calls
Display and Debug 
ISDNPerform the display and debugging commands in all views.
Ta b l e 228   Display and debug ISDN
OperationCommand
Configure an interface to initiate connection using voice 
callsdialer data2voice
Configure the interface to initiate connection using data 
callsundo dialer data2voice
OperationCommand
Configure an interface to process the received calls as 
voice callsIsdn voice2data
Configure the interface to process the received calls as 
data callsundo isdn voice2data
OperationCommand
Display the current activated call 
information of ISDN interfacedisplay isdn active-channel [ 
interface type number ] 
Display the value of ISDN DSS1 signaling 
timerdisplay isdn q931-timer
Display the value of ISDN QSIG signaling 
timerdisplay isdn qsig-timer [ interface 
type number ] 
Display the current status of ISDN interfacedisplay isdn call-info [ interface 
type number ] 
Enable the debugging of ISDN CCdebugging isdn cc [ interface type 
number ]
Enable the debugging of ISDN q921 
protocoldebugging isdn q921 [ interface 
type number ]
Enable the debugging of ISDN q931 
protocoldebugging isdn q931 [ interface 
type number ] 
						

							Typical Configuration Example193
Typical Configuration 
Example
Interconnect Routers for 
Data Transmission via 
ISDN PRI LineI. Networking Requirement
Router A is connected with router B via WAN, as shown in the following diagram.
II. Networking Diagram
Figure 56   Networking diagram of ISDN protocol configuration example
III. Configuration Procedure
1Configure Router A:
aCreate an ISDN PRI interface.
[Router]controller e1 0
[Router-E1-0]pri-set
[Router-E1-0]quit
bConfigure the ISDN PRI interface.
[Router]interface serial 0:15
[Router-Serial0:15]ip address 202.38.154.1 255.255.0.0
[Router-Serial0:15]dialer route-info ip 202.38.154.2 8810154
[Router-Serial0:15]dialer-group 1
[Router-Serial0:15]quit
[Router]dialer-rule 1 ip permit
2Configure Router B:
The parameter configuration on Router B is almost the same as Router A, so it will 
not be mentioned here.
 
Typical ISDN DoV 
Configuration ExampleI. Networking Requirements
RouterA and Router are connected over an ISDN and RouterA will initiate a call to 
RouterB. The call is handled in the way of processing a voice call, and RouterA and 
RouterB transmit data after the call is set up.
Enable ISDN QSIG signaling debuggingdebugging isdn qsig { alarm | 
call-state | error | information | 
message | all 
} [ interface type 
number ]
ISDN Exchange 202.38.154.1
202.38.154.2 8810152
8810154 Router A
Router B cE1/PRI
cE1/PRI Network 
						

							194CHAPTER 15: CONFIGURING ISDN PROTOCOL
II. Networking Diagram
Figure 57   Networking for ISDN DoV
III. Configuration Procedure
1Configure Router A:
[Router]dialer-rule 1 ip permit
[Router]interface bri 0
[Router-Bri0]ip address 100.1.1.1 255.255.255.0
[Router-Bri0]dialer-group 1
[Router-Bri0]dialer route ip 100.1.1.2 8810148
[Router-Bri0]dialer data2voice
2Configure Router B:
[Router]dialer-rule 1 ip permit
[Router]interface bri 0
[Router-Bri0]ip address 100.1.1.2 255.255.255.0
[Router-Bri0]dialer-group 1
[Router-Bri0]dialer route ip 100.1.1.1 8810152
[Router-Bri0]isdn voice2data
Fault Diagnosis and 
Troubleshooting of 
ISDNFault: Two routers are connected via an ISDN PRI line, but pinging the 
routers is not successful.
Troubleshooting:
1Execute the display isdn call-info command. If the system prompts “there is 
no isdn port”, it means that there is no ISDN PRI port, and you should configure 
one. For the configuration, refer to the section “cE1/PRI Interface and cT1/PRI 
Interface Configuration” in 
Operation Manual - Interface.
2If enabling Q.921 information debugging and debugging information “ISDN-D 
send data error” is output, it indicates that the physical layer is not activated. You 
can try to use the commands 
shutdown and undo shutdown to disable and 
re-enable the related interface.
3Check whether the dialer is configured correctly. If the dialer is configured 
correctly and no “ISDN-D send data error” is displayed, then its possible the ISDN 
line is not connected well.
BRI0ISDN
NetworkBRI0
RouterA RouterB
88101528810148 
						

							16
CONFIGURING LAPB AND X.25
This chapter contains information on the following topics:
■X.25 and LAPB Protocols Overview
■Configure LAPB
■Configure X.25
■Configure X.25 over Other Protocols
■Display and Debug LAPB and X.25
■Typical LAPB Configuration Example
■Typical X.25 Configuration Example
■Fault Diagnosis and Troubleshooting of LAPB
■Fault Diagnosis and Troubleshooting of X.25
X.25 and LAPB 
Protocols OverviewX.25 protocol is the interface procedure between the data terminal equipment 
(DTE) and data circuit-terminating equipment (DCE). In 1974, CCITT issued the 
first draft of X.25, whose initial files were based on the experiences and 
recommendations of Telenet and Tymnet of USA and Datapac packet-switched 
networks of Canada. It was revised in 1976, 1978, 1980 and 1984, added many 
optional service functions and facilities.
With X.25, two DTE can communicate with each other via the existing telephone 
network. X.25 sessions are established when one DTE device contacts another to 
request a communication session. The DTE device that receives the request can 
either accept or refuse the connection. If the request is accepted, the two systems 
begin full-duplex information transfer. Either DTE device can terminate the 
connection. After the session is terminated, any further communication requires 
the establishment of a new session.
X.25 is the protocol of point-to-point interaction between DTE and DCE. DTE 
usually refers to the host or terminal at the user side, and DCE usually refers to the 
synchronous modem. DTE is connected with DCE directly, DCE is connected to a 
port of packet switching exchange, and some connections are established 
between the packet switching exchanges, thus forming the paths between 
different DTE. In an X.25 network, the relation between entities is shown in the 
following diagram: 
						

							196CHAPTER 16: CONFIGURING LAPB AND X.25
Figure 58   X.25 network model
The X.25 protocol suite maps to the lowest three layers of the OSI (Open System 
Interconnection) reference model. The following protocols are typically used in 
X.25 implementations: Packet-Layer Protocol (PLP), Link Access Procedure 
Balanced (LAPB), and other physical-layer serial interfaces. X.25 layer 3 
(packet-layer protocol) describes the format of packet used by the packet layer 
and the procedure of packet switching between two layer 3 entities. X.25 layer 2 
(link-layer protocol), also called LAPB (Link Access Procedure Balanced), defines the 
format and procedure of interactive frames between DTE and DCE. X.25 layer 1 
(physical-layer protocol) defines some physical and electrical characteristics in the 
connection between DTE and DCE. The above relation is shown in the following 
diagram.
Figure 59   DTE/DCE interface
A virtual circuit is a logical connection created to ensure reliable communication 
between two network devices. A virtual circuit denotes the existence of a logic, 
bi-directional path from one DTE device to another across an X.25 network. Two 
types of X.25 virtual circuits exist: permanent virtual circuit (PVC) and switched 
virtual circuit (SVC). PVCs are permanently established connections used for 
frequent and consistent data transfers, whereas SVCs are temporary connections 
used for sporadic data transfers.
DCEDTE
DCE
DCE
DTE
DTE
PSE
PSE
PSE
PSN
DTE:  Data Terminal Equipment
DCE:  Data Circuit-terminating Equipment
PSE:  Packet Switching Equipment
PSN:  Packet Switching Network
OSI reference model
7
6
5
4
3
2
1
X.25
Packet layer
interface
Link layer
interface
Physical layer
interface
DTEDCE
X.25
Physical layer
X.25
Link layer
X.25
Packet layer
X.25
Physical layer
X.25
Link layer
X.25
Packet layer