CCNA- part 9 isdn

Completing ISDN Calls
Module 9
© 2002, Cisco Systems, Inc. All rights reserved. 1

Objectives
Upon completing this module, you will be able to:
• Configure ISDN BRI, ISDN PRI, and legacy DDR, given a
functioning remote access router and a physical ISDN
connection
• Use show commands to identify the anomalies in the
ISDN BRI, ISDN PRI, and legacy DDR configurations,
given a functioning remote access router and a physical
ISDN connection
• Use debug commands to identify the anomalies in the
ISDN BRI, ISDN PRI, and legacy DDR configurations,
given a functioning remote access router and a physical
ISDN connection DDR = Dial on Demand Routing
ISDN = Integrated Services Digital Network
BRI = Basic Rate Interface
PRI = Primary Rate Interface
© 2002, Cisco Systems, Inc. All rights reserved. ICND v2.0—9-2

9.1 Configuring ISDN BRI and
PRI
© 2002, Cisco Systems, Inc. All rights © 2002, Cisco Systems, Inc. All rights rerseesrevrevde.d. ICND v2.0—9-3 3

Objectives
Upon completing this lesson, you will be able to:
• Configure ISDN BRI and ISDN PRI, given a functioning
router and a physical ISDN connection
ISDN BRI and PRI configurations, given a functioning
router and a physical ISDN connection
• Use debug commands to identify the anomalies in the
ISDN BRI and PRI configurations, given a functioning
remote access router and a physical ISDN connection

What Is ISDN?
Various ISDN environments
ISDN Switches
• Voice, data, video, and special services
PBX = Private Branch Exchange

ISDN Standards (ITU-T)

ISDN Standards
Layer 3
• Q.931 provides a network-layer protocol
• This ISDN call control protocol follows the recommendations for the ISDN
signaling layer
• ISDN uses out-of-band signaling
• ISDN addressing generally follows E.164
Layer 2
• Q.921 LAPD data link protocol, the recommendation specifies the framing
format for the ISDN call control message
• in other words, LAPD encapsulated the Q.931 signaling message
Layer 1
• I.430/I.431 recommendation specifies the ISDN physical-layer interfaces
• I.430 for the basic interface
• I.431 for the primary interface

ISDN Access Options
23 B channels in the United States and Japan
30 B channels in Europe and India NT1 = Network Termination Type 1

BRI and PRI Call Processing
The D channel is always up
The B channels are used to send data.
SS7 = Signaling System 7

ISDN Reference Points (Interfaces)
U interface ensures rate conversion, clock
synchronization, frame alignment, and adequate power
supply, and provides an operational and maintenance
control point for the service provider.
S interface enables the connection for ISDN devices
and provides access to the useful transmission rate
T interface corresponds to the S interface from the
provider perspective. The T interface offers the total
transmission rate
R interface enables connection for non-ISDN (R type)
devices

ISDN Device Hardware
TE1 = a native ISDN device that can connect
directly to its S/T interface
NT1 = an external device that converts the 4-wire
connection on the T interface to a 2-wire U line
interface
NT = Network Termination
NT2 = a splitting device
TE = Terminal Equipment
TA = Terminal Adapter
TE2 = a non-native ISDN device that requires a TA
for its S interface signals
TA = an external device required on non-native
ISDN devices.

ISDN Functions and Reference Points
• Functions are devices or
hardware.
• Reference points are
demarcations or interfaces.

Cisco ISDN BRI Interfaces

Cisco ISDN PRI Interfaces
PRI = Primary Rate Interface
CSU = Channel Service Unit
CT = Channel Termination

ISDN Switch Types
Many providers use many
different switch types.
Services vary by region and country.

Configuring ISDN BRI
Step 1: Specify the ISDN switch type.
Router(config)#isdn switch-type switch-type
Router(config-if)#isdn switch-type switch-type
Or
• The command specifies the type of ISDN switch with
which the router communicates.
• Other configuration requirements vary for specific
providers.

Configuring ISDN BRI (cont.)
Step 2: (Optional) Setting SPIDs
Router(config-if)#isdn spid1 spid-number [ldn]
• Sets a B channel SPID required by many service
providers
Router(config-if)#isdn spid2 spid-number [ldn]
• Sets a SPID for the second B channel
Some service providers require SPIDs to authenticate that a call
requests are within contract specifications
SPID = Service Profile Identifier

Configuring ISDN PRI
Step 1: Specify the ISDN switch type.
Router(config)#isdn switch-type switch-type
Step 2: Select the controller.
Router(config)#controller controller slot/port
Step 3: Establish the interface port
to function as PRI .
Router(config-controller)#pri-group timeslots range
Refer PCM-TDM Channels

ISDN PRI Examples
T1 Sample Configuration
Router(config)#controller T1 3/0
Router(config-controller)#framing esf
Router(config-controller)#linecode b8zs
Router(config-controller)#pri-group timeslots 1-24
Router(config-controller)#interface Serial3/0:23
Router(config-if)#isdn switch-type primary-5ess
Router(config-if)#no cdp enable
E1 Sample Configuration
Router(config)#controller E1 3/0
Router(config-controller)# framing crc4
Router(config-controller)# linecode hdb3
Router(config-controller)# pri-group timeslots 1-31
Router(config-controller)#interface Serial3/0:15
Router(config-if)# isdn switch-type primary-net5
Router(config-if)# no cdp enable

Verifying the ISDN Configuration
Router#show isdn active
• Displays current call information
Router#show interfaces bri0
• Displays statistics for the BRI interface configured
on the router
Router#show isdn status
• Displays the status of an ISDN connection

Troubleshooting the ISDN Configuration
Router#debug isdn q921
• Shows ISDN Layer 2 messages
• Shows ISDN call setup and teardown activity (Layer 3)
Router#debug ppp authentication
• Displays the PPP authentication protocol messages
Router#debug ppp negotiation
• Displays information on PPP link establishment
Router#debug ppp error
• Displays protocol errors associated with PPP

Summary
• ISDN defines a digital architecture that provides
integrated voice and data capability using the public
switched network.
• ISDN specifies two standard access methods, BRI
and PRI.
• To establish an ISDN call, the D channel is used
between the routers and switches, and SS7 signaling is
used between the switches.
• ISDN functions are hardware devices while reference
points are interfaces between devices.
• Cisco devices can be physically configured with
different ISDN options, which dictate what additional
equipment, if any, is needed to run ISDN.

Summary (Cont.)
• You must configure your router to identify the type
of switch it will be communicating with, which
depends in part on the country the switch is in.
• To enable ISDN BRI, you use isdn switch-type and
isdn spid commands.
• To enable ISDN PRI, use the pri-group command.
• Use show commands to verify that your ISDN
configuration is functioning properly.
• You can use debug commands to troubleshoot your
ISDN configuration.

9.2 Configuring Dial-on-
Demand Routing
© 2002, Cisco Systems, Inc. All rights © 2002, Cisco Systems, Inc. All rights rerseesrevrevde.d. ICND v2.0—9-24 24

Objectives
Upon completing this lesson, you will be
able to:
• Configure legacy DDR, given a functioning remote
access router and a physical ISDN connection
legacy DDR configurations, given a functioning
remote access router and a physical ISDN
connection
• Use debug commands to identify the anomalies in
the legacy DDR configurations, given a functioning
remote access router and a physical ISDN
connection

What Is Dial-on-Demand Routing?
• Connects when needed
• Disconnects when finished
• ISDN or PSTN
Public Switched Telephone Network

When to Use DDR
• Low volume periodic connections
• Small amounts of data
• Cost savings over permanent WAN links

Generic DDR Operation
1. Route to destination is determined.
2. Interesting packets dictate DDR call.
3. Dialer information is looked up.
4. Traffic is transmitted.
5. Call is terminated after a user-defined idle period
Static routes are configured between the routers to avoid periodic transmissions over the WAN that would be caused by dynamic routing.

Configuring DDR
1
2
3
Define static routes—What route do I use?
Specify interesting traffic—What traffic
enables the link?
Configure the dialer information—What
number do I call?

Defining Static Routes

Specifying Interesting Traffic
dialer-list 1 protocol ip permit
• Any IP traffic will initiate the link without access lists.
Or
dialer-list 1 protocol ip list 101
access-list 101 deny tcp any any eq ftp
access-list 101 deny tcp any any eq telnet
access-list 101 permit ip any any
Denies FTP
Denies Telnet
• Any IP traffic, except FTP and Telnet, will initiate the linking.
• Using access lists gives finer control.

Configuring the Dialer Information
• Applies rules defined by
dialer-list to individual
interfaces
hostname Home
!
isdn switch-type basic-5ess
!
username central password cisco
interface BRI0
ip address 10.1.0.1 255.255.255.0
encapsulation ppp
dialer idle-timeout 180
dialer map ip 10.1.0.2 name Central 5552000
dialer-group 1
no fair-queue
ppp authentication chap
!
router rip
network 10.0.0.0
!
no ip classless
ip route 10.10.0.0 255.255.0.0 10.1.0.2
ip route 10.20.0.0 255.255.0.0 10.1.0.2
!
Both Values
Must Match

Configuring the Dialer Information (Cont.)

Configuring the Dialer Information (Cont.)
The dialer-map command maps the remote protocol
address to a telephone number.
You need this command if you will be dialing
multiple sites.
If you will be dialing only one site, you could use
an unconditional dialer string command
It always dials the one phone number regardless of
the traffic destination.

Optional Legacy DDR Commands
Router(config-if)#dialer load-threshold load
[outbound | inbound | either]
• Establishes the amount of traffic on the link before a
second link is enabled
Router(config-if)#dialer idle-timeout seconds
• Establishes the idle time before disconnect
• The dialer idle-timeout has a default value of 120.

Legacy DDR Configuration Tasks
Summarized
3
1
2
hostname Home
!
isdn switch-type basic-5ess
!
username central password cisco
interface BRI0
ip address 10.1.0.1 255.255.255.0
encapsulation ppp
dialer idle-timeout 180
dialer map ip 10.1.0.2 name Central 5552000
dialer-group 1
no fair-queue
!
router rip
network 10.0.0.0
!
no ip classless
ip route 10.10.0.0 255.255.0.0 10.1.0.2
ip route 10.20.0.0 255.255.0.0 10.1.0.2
!

Dialer Profiles Overview

Dialer Profile Elements

Dialer Profile Configuration Concepts
and Commands

Configuring Dialer Interfaces
interface dialer1
ip address 10.1.1.1
255.255.255.0
encapsulation ppp
dialer remote-name Smalluser
dialer string 5554540
dialer idle-timer 180
dialer pool 1
dialer-group 1
!
interface dialer2
ip address 10.2.2.1
255.255.255.0
encapsulation ppp
dialer remote-name Mediumuser
dialer pool 1
dialer-group 2
(cont.)
interface dialer3
ip address 10.3.3.1 255.255.255.0
encapsulation ppp
dialer remote-name Poweruser
dialer pool 1
dialer-group 3

Configuring Physical Interfaces

Verifying DDR and ISDN Operation
Router#ping or telnet
• Triggers a link
Router#show dialer
•Displays current status of the link
Router#show isdn active
•Displays call status while call is in progress
Router#show isdn status
•Displays the status of an ISDN connection
Router#show ip route
•Displays all routes, including static routes

Verifying Dialer Profiles Operation
NASX#show dialer interface bri0
BRI0 - dialer type = ISDN
Dial String Successes Failures Last called Last status
5553872 6 0 19 secs Successful
0 incoming call(s) have been screened.
BRI0: B-Channel 1
Idle timer (120 secs), Fast idle timer (20 secs)
Wait for carrier (30 secs), Re-enable (15 secs)
Dialer state is data link layer up
Dial reason: ip (s=10.1.1.8, d=10.1.1.1)
Interface bound to profile Dialer0
Time until disconnect 102 secs
Current call connected 00:00:19
Connected to 5553872 (system1)
BRI0: B-Channel 2
Idle timer (120 secs), Fast idle timer (20 secs)
Wait for carrier (30 secs), Re-enable (15 secs)
Dialer state is idle

Troubleshooting DDR and ISDN Operation
• Shows ISDN Layer 2 messages
• Shows ISDN call setup and teardown activity
Router#debug dialer [events | packets]
• Displays DDR debugging information about the packets
received on a dialer interface
Router(config-if)#shutdown
• Clears currently established connections from the
interface

debug isdn q921 Example
Jan 3 14:52:24.475: ISDN BR0: TX -> INFOc sapi = 0 tei = 64 ns = 5 nr = 2
i = 0x08010705040288901801837006803631383835
Jan 3 14:52:24.503: ISDN BR0: RX <- RRr sapi = 0 tei = 64 nr = 6
Jan 3 14:52:24.527: ISDN BR0: RX <- INFOc sapi = 0 tei = 64 ns = 2 nr = 6
i = 0x08018702180189
Jan 3 14:52:24.535: ISDN BR0: TX -> RRr sapi = 0 tei = 64 nr = 3
Jan 3 14:52:24.643: ISDN BR0: RX <- INFOc sapi = 0 tei = 64 ns = 3 nr = 6
i = 0x08018707
Jan 3 14:52:24.655: ISDN BR0: TX -> RRr sapi = 0 tei = 64 nr = 4
%LINK-3-UPDOWN: Interface BRI0:1, changed state to up
Jan 3 14:52:24.683: ISDN BR0: TX -> INFOc sapi = 0 tei = 64 ns = 6 nr = 4
i = 0x0801070F
Jan 3 14:52:24.699: ISDN BR0: RX <- RRr sapi = 0 tei = 64 nr = 7
%LINEPROTO-5-UPDOWN: Line protocol on Interface BRI0:1, changed state to up
%ISDN-6-CONNECT: Interface BRI0:1 is now connected to 61885 goodie
Jan 3 14:52:34.415: ISDN BR0: RX <- RRp sapi = 0 tei = 64 nr = 7
Jan 3 14:52:34.419: ISDN BR0: TX -> RRf sapi = 0 tei = 64 nr = 4

debug isdn q931 Examples
TX -> SETUP pd = 8 callref = 0x04
Bearer Capability i = 0x8890
Channel ID i = 0x83
Called Party Number i = 0x80, `415555121202'
RX <- CALL_PROC pd = 8 callref = 0x84
Channel ID i = 0x89
RX <- CONNECT pd = 8 callref = 0x84
TX -> CONNECT_ACK pd = 8 callref = 0x04....
RX <- SETUP pd = 8 callref = 0x06
Bearer Capability i = 0x8890
Channel ID i = 0x89
Calling Party Number i = 0x0083, `81012345678902'
TX -> CONNECT pd = 8 callref = 0x86
RX <- CONNECT_ACK pd = 8 callref = 0x06
Call Setup
Procedure for
Outgoing Call
Call Setup
Procedure for
Incoming Call

debug dialer Examples
Router#debug dialer events
Dialing cause: Serial0: ip (s=172.16.1.111 d=172.16.2.22)
Router#debug dialer packets
BRI0: ip (s=10.1.1.8, d=10.1.1.1), 100 bytes, interesting (ip PERMIT)

Resolving Outbound Call Problems
Cause
Missing or incorrect
“interesting traffic”
definitions
Incorrect interface state
Misconfigured dialer
map
Misconfigured dialer
profile
Suggested Actions
Verify the configuration using show
running-configuration
Ensure that the interface state is “up/up”
(spoofing)
Make sure the dialing interface has at
least one dialer map statement
Make sure the dialer interface is
configured with a dialer pool X command

Summary
• Dial-on-demand routing refers to a collection of
Cisco features that allows two or more Cisco
routers to establish a dynamic connection over
simple dialup facilities.
• DDR operates by first determining the route to
the destination, then, if the traffic is
“interesting,” initiating a call.
• To configure DDR, first define the static routes,
then specify interesting traffic, and finally
configure the dialer information.
• Use static routes across a DDR link so that the
number is not dialed just for routing updates.

Summary (Cont.)
• DDR calls are triggered by “interesting” traffic, which can
be defined based on protocol, source address,
destination address, or a variety of other criteria.
• Use the dialer-group and dialer map commands on an
interface to associate a port and dialer-string with a
dial list.
• To configure ISDN PRI with legacy DDR, you will
configure dialer rotary groups and dialer profiles.
• You use show commands to display information about
DDR configuration.
• You can use debug commands to help troubleshoot
problems with a DDR configuration.

Visual Objective 9-1: Completing and
ISDN BRI Call and DDR
Pod Router BRI
A 10.130.0.2
B 10.135.0.2
C 10.140.0.2
D 10.145.0.2
E 10.150.0.2
F 10.155.0.2
G 10.160.0.2
H 10.165.0.2
I 10.170.0.2
J 10.175.0.2
K 10.180.0.2
L 10.185.0.2

CCNA- part 9 isdn

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