ccna chapter 10 by jetarvind kumar madhukar
TRANSCRIPT
Release 16/07/2009Jetking Infotrain Ltd.
Chapter Objectives
Explain ISDN features Explain ISDN devices Explain ISDN connections Configure BRI Configure PRI Verify ISDN Connections
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Recall
WAN is a network that spans a large geographical area
Data-Link layer protocols are commonly called the data link protocols, which communicate between two devices
PAP is a insecure protocol because the username and password is sent in plain text
Use debug ppp authentication to troubleshoot PPP Using CHAP protocol the server sends challenge
messages to the node. The node calculates and sends the results back to the server
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ISDN Features
ISDN provides Wide Area Network (WAN) services in incremental values of 64 kbps
The features of ISDN are: Speed Multiple Device Support Inexpensive
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ISDN Channels and Services
ISDN network transmits information through the three logical digital communication channels such as Bearer (B) channel, Data (D) channel and Hybrid (H) channel
H channel can be implemented as H0, H10, H11, H12
ISDN supports two types of connections such as the Basic Rate Interface (BRI) and Primary Rate Interface (PRI)
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ISDN Devices
The ISDN devices are given as follows: Network Termination Device 1 (NT1) Network Termination Device 2 (NT2) ISDN Router Terminal Equipment 1 (TE1) Terminal Equipment 2 (TE2) Terminal Adapter (TA)
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ISDN Connections
ISDN is a channelized service A channelized service splits a wire into many logical
channels or time slots Some of the common terms that are used in
channelized connections are: Digital Signal 0 (DS0) Digital Signal 1 (DS1) T1 E1
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ISDN Protocols The following are ISDN protocols dealing with certain
issues: Protocols with E as the beginning letter deal with using
ISDN on the existing telephone lines Protocols with I as the beginning letter deal with ISDN
concepts, aspects and services Protocols with Q as the beginning letter deal with
switching and signaling. These protocols allow you to connect to the ISDN and troubleshoot the network. The Q protocols include the following: Q.921 Q.931
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Switch Types and Connections - I
Switch Type Connection Type
basic-5ess BRI
basic-dms100 BRI
basic-ni1 BRI
basic-ni2 BRI
basic-1tr6 BRI
basic-net3 BRI
basic-nwnet3 BRI
basic-nznet3 BRI
basic-ts013 BRI
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Switch Types and Connections - II
ntt BRI
vn2 BRI
vn3 BRI
vn4 BRI
vn5 BRI
pri-4ess PRI
pri-5ess PRI
pri-dms100 PRI
pri-nt PRI
pri-net5 PRI
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Selecting Router ISDN Interface To select a Cisco router with the correct ISDN
interface: Check whether the router supports ISDN BRI Identify the NT1 provider. NT1 ends the local loop
to the Central Office (CO) of the service provider Check whether NT1 is Customer Premises
Equipment (CPE)
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ISDN Call Setup Procedure
To set up an ISDN call between the router and the ISDN switch, the D channel is used whereas, between the switches within the service provider’s network, Signaling System 7 (SS7) is used
By default, the D channel is always enabled During the ISDN call, the calling host sends a call
setup request Before the actual connection is established, many
different messages are sent across such as progress messages and alert messages
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Configuring BRI
You can configure the BRI for the router after connecting the ISDN equipment
The generic steps to configure BRI are: Setting an user name and password Setting the switch type Configuring ISDN interface on a router Setting the Service Profile Identifier (SPID)
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Setting the SPID
Service Profile IDentifier (SPID) is a set of numbers for BRI connections that have a National ISDN-1 or Nortel DMS-100 switch
The SPID consists of the ten-digit telephone number for the connection and extra identification digits
The SPIDs are provided along with the switch carrier
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Configuring PRI - I You need to configure additional parameters for PRI on
your router After setting the switch type, you need to configure the
T1/E1 controller card and the serial interface of the controller card
The different configuration settings for the controller card include: Framing Line code Clock source Timeslots
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Configuring PRI - II
The generic steps to configure PRI are: Setting the ISDN switch type with which the router
will communicate Selecting the controller and specifying the type
(T1/E1), framing type and line coding for the provider
Setting the port to function as PRI and specifying the PRI slot for T1 or E1 and the speed
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Verifying ISDN Connections
After configuring the interfaces, you need to verify that they have been configured properly
You can verify the ISDN connections using two commands show interface command show isdn status command
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ISDN Verification Commands - I
Command Description
ping and telnet Enables you to ping or telnet the remote router when the link is established without considering the interesting traffic list
show dialer Provides dialer information that includes status of the link, idle time, length of the call, router to which the interface is connected
show isdn active Displays the phone number and whether the call is active
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ISDN Verification Commands - IIshow isdn status Displays the detailed status of the ISDN
interfaces
show ip route Displays all the routes of the router
debug isdn q921 Enables you to view layer 2 information
debug isdn q931 Enables you to view layer 3 information
debug dialer Provides the call setup and disabled activities
isdn disconnect interface bri 0 Enables you to clear the interface and disconnect the connection
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Dial on Demand Routing
Cisco provides Dial on Demand Routing (DDR) feature that allows the Cisco router to dial an ISDN when it receives an interesting traffic
The interesting traffic is referred as IP traffic fulfilling specific criteria such as particular protocol and highly secured destination address
If a traffic using particular criterion is set as interesting traffic, the traffic is given the highest priority during the transmission
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Making a phone connection - I To make a phone connection, the DDR goes through the
following process: When a packet is received, the router checks the
routing table to locate the destination The router determines if the packet is interesting. The router establishes DDR connection by dialing the
ISDN. When the received packet is interesting and the DDR is not active, the router makes a phone call to establish connection. If the received packet is not interesting and the DDR is not active, the router drops the packet. However, the router transmits all the packets if the DDR already active
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Making a phone connection - II
Once the connection is established, the router transmits the packets from the DDR interface
The router terminates the connection if no packets are to be transmitted or the connection remains idle for certain period
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DDR Configuration - I
You can allow the Cisco router to perform the DDR process by configuring it
DDR can be used in the following situations: The telecommuters need to connect to the
company network periodically There are offices that need to send transactions
or requests to the main computer at the central office
The users need to retrieve the e-mail from the ISP
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DDR Configuration - II
The generic steps to configure legacy DDR are: Configuring static routes that are the routes for
remote networks Specifying which traffic is interesting Activating dialer list that contains the information
about the traffic that can generate calls Configuring a dialer map that informs the router to
make a call using legacy DDR
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Configuring Static Routes
The DDR feature of Cisco allows you to prevent unwanted traffic from making phone calls and keeping the line busy
configuring static routes helps in avoiding other traffic to trigger calls
The ip route command enables you to define the static route. The syntax of this command is:
ip route network_IP_address_# subnet_mask remote_router’s_IP_address|router_interface [administrative_distance]
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Specifying Interesting Traffic
Access Lists (ACLs) allows you to specify the interesting traffic on the router
Using the dialer-list command, you can allow only the IP traffic to establish connection
The dialer-list command enables you to specify which traffic is interesting. The syntax of this command is:
dialer-list [list_#] protocol [protocol_name] permit|deny access-list [ACL_#]
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Activating Dialer List
You need to activate the dialer list on the DDR interface after the list is created
It is necessary to activate the list because the list is not an ACL and it only specifies which traffic is interesting traffic by referring an ACL
To activate the dialer list, you should use the dialer-group command. The syntax of this command is given as follows:
dialer-group dialer_list_#
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Configuring Dialer Maps
Once you finish specifying the interesting traffic and activating the dialer list on the DDR interface, you can specify dialer information to the router
The dialer map command gives dialer information for the router to make phone calls. The syntax of the command is:
dialer map protocol_name destination_router_address name [remote_router] speed [56|64] [broadcast] [destination_phone_number]
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Dialer Profiles
With the help of dialer profiles, the following tasks can be performed: Configuring B channels with different IP subnets Using encapsulation on the B channel Setting DDR parameters for the B channels Eliminating the garbage of ISDN B channels by
allowing ISDN BRI interfaces to associate with multiple dialer pools
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Configuring Dialer Profiles
You can configure many dialer interfaces on the router wherein each interface will contain complete information about the possible destinations
The initial steps in configuring dialer profiles include configuring static routes and dialer list similar to legacy DDR
you need to configure the dialer and the physical interfaces then
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Verifying DDR Configuration
After configuring the interfaces, you need to verify that they have been configured properly
To verify the DDR configuration, there are three commands: show dialer interface show isdn active show isdn status
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Troubleshooting ISDN DDR
The show and debug commands enable you to verify and troubleshoot the DDR connections show command - You can use the show dialer
command to view the DDR interfaces that made the phone calls
debug command - You can use the debug dialer command to view the DDR process to enable or disable the connection
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Case Study
The Blue Diamond Steel company opened a new branch at Hyderabad. The organization uses regular telephone line for data transmission. All the departments of the Hyderabad branch send the details of their daily transactions to the Gujarat branch. The files that contain the transaction details are very large in size.
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Problem
The data transmission is slow which incurs a lot of expense on each call
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Suggested Solution
Implement Cisco routers in the network and configure ISDN on each router. The Cisco routers provide Dial on Demand Routing (DDR) feature, which allows the router to call the ISDN when it receives important traffic. Setup the PRI service for data transmission, which provides 23 B channels and 1 D channel
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Summary - I
The Integrated Services Digital Network (ISDN) is a set of international standards that define data transmission across digital circuits
ISDN provides Wide Area Network (WAN) services in incremental values of 64 kbps
ISDN requires only 2 seconds to complete a call as compared to analog signals that require 30 seconds
Network Termination Device 1 (NT1) provides an interface between the ISDN BRI line and other devices
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Summary - II
Network Termination Device 2 (NT2) communicates with the ISDN protocols
ISDN Router enables multiple computers on a LAN to share a single ISDN BRI connection
Terminal Adapter (TA) converts some other form of signaling to ISDN to enable non-ISDN devices, such as the TE2 to work the 2-wire ISDN network
The U point is a 2-wire interface for connecting to the (NT1)
The division of the wire into logical time slots is termed as Time Division Multiplexing (TDM)
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Summary - III
The S reference point provides a 4-wire interface between the NT1 and the ISDN networking equipment such as an ISDN adapter or a router
Basic Rate Interface (BRI) consists of two B channels and one D channel
Primary Rate Interface (PRI) consists of multiple B and D channels
The ISDN interfaces can be configured using the interface command
The Internet Service Provider (ISP) provides the switch type for the ISDN connection
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Summary - IV
Service Profile IDentifier (SPID) is a set of numbers for BRI connections that have a National ISDN-1 or Nortel DMS-100 switch
The show interface command enables you to view the ISDN interface configuration
The show isdn status command enables you to view the detailed status of the ISDN interfaces