CCNA4 Week4

• Summary of ISDN and PPP

• ISDN and PPP labs

• Resits of TCT if appropriate

• Issue revised schedule

PPP

• HDLC is specific to Cisco routers

• PPP is used for connecting to other routers

• PPP incorporates optional authentication

• Used with ISDN for authentication

• Challenge Handshake Authentication Protocol (CHAP) is most commonly used

Commands

• Router1(config-if)# encapsualtion ppp

• Router1(config-if)# ppp authentication chap

• Router1(config)# username Router2 password cisco

• This assumes that the enable password of Router2 is cisco

ISDN Functional Groups

• TE1 – Terminal Eqipment 1 (TE1) – An ISDN compatible device.

• TE2 – Terminal Eqipment 2 (TE2) – Non ISDN compatible device

• Terminal Adapter (TA) – allows non-isdn device to work on an ISDN network

• Network Termination Type 1 (NT1) – Connects 4 wire ISDN wiring to local loop 2 wire. CPE equipment in US/ Europe

ISDN Functional Groups

• Network Termination Type 1 (NT2) – Switches traffic between devices. Intelligent device often a private branch exchange (PBX). Not always present

• Line Termination (LT) – Exchange side NT1.• Exchange Termination (ET) – A subscriber line

card in the ISDN exchange.• Local Exchange (LE) – The ISDN central office

(CO) that houses the ISDN switch. LT and ET are sometimes referred to as the Local Exchange. The LE implements the ISDN protocol and is part of the network.

ISDN

• ISDN can be confiured using two methods:-

• Legacy DDR (binding to an interface)

• Dailer Profiles

Basic ISDN configuration

• Specify switch type

• Specify SPIDs in interface configuration mode (Not necessary in UK)

• Set encapsulation type and characteristics

Configuration of DDR over ISDN

• Define interesting traffic using dialer-list command

• Assign traffic definitions to an interface using dialer-group command

• Define the destination address, hostname and telephone number using dialer-map command

• Optional parameters include dialer idle-timeout, out fast idle and dialer-load threshold.

Exampe DDR ISDN configuration

Router (config)# isdn switch-type basic-ni dialer-list 1 protocol ip permit username OtherRouter password cisco int bri0/0

Router (config-if)# encapsulation ppp isdn spid 1 510555400000001 5554000 isdn spid 2 510555400010001 5554001 ip address 10.0.0.1 255.255.255.0 dialer map ip 10.0.0.2 name OtherRouter 55554002 ppp encapsulation chap dailer-group 1

Call Setup

• Different ISDN switches use different call setup and teardown procedures. Depending on the switch type, you may or may not get all the steps shown in the figure. At a minimum, setup, call proceeding, connect, and connect acknowledge messages should be exchanged.

Limitations

• Legacy DDR is limited because the configuration is applied directly to a physical interface. Since the IP address is applied directly to the interface, then only DDR interfaces configured in that specific subnet can establish a DDR connection with that interface. This means that there is a one-to-one correspondence between the two DDR interfaces at each end of the link.

Legacy DDR

• is based on static binding between destination call specification and the physical interface configuration.

• The physical interface is locked into one configuration• Uses dialer maps• Dialer map statements can be used for more than one

destination provided the other configured parameters such as idel-timer and ppp authentication are the same.

• If different parameters required more than one physical interface is required.

Example

• A Remote Access Server is a router capable of receiving/ placing calls

• In the example above the server would require three separate interfaces as different physical characteristics are applied to the physical interfaces

Dialer profiles

• Dialer profiles remove the configuration from the interface receiving or making calls and only bind the configuration to the interface on a per-call basis.

• Dialer profiles allow physical interfaces to dynamically take on different characteristics based on incoming or outgoing call requirements.

To configure the dialer interface, perform the following tasks:

1. Configure one or more dialer interfaces with all the basic DDR commands: – IP address – Encapsulation type and authentication – Idle-timer – Dialer-group for interesting traffic

2. Configure a dialer string and dialer remote-name to specify the remote router name and phone number to dial it. The dialer pool associates this logical interface with a pool of physical interfaces.

3. Configure the physical interfaces and assign them to a dialer pool using the dialer pool-member command.