Configuring Legacy DDR

Step 1: Configure static routes on router.


Using static routes instead of dynamic routing will save on ISDN costs. The link will not always be up because routing updates trigger link to become active

Edmonton#config t


Edmonton(config)#ip route


Step 2 (Option 1): Define interesting traffic without access lists.


Specifies what type of traffic will trigger the router to make an ISDN call to establish the link

Tip: The dialer-list and dialer-group commands can be compared to the access-list and access-group commands in access control lists (ACLs).

Edmonton(config)#dialer-list 1 protocol ip permit

States that all IP traffic is interesting

Edmonton(config)#int bri 0


Edmonton(config-if)#dialer-group 1

Groups all dialer-list 1 statements together to apply to this interface

Step 2 (Option 2): Define interesting traffic with access lists (for better control).


Using access lists within dialer lists gives you more control as to what traffic is defined as interesting

Edmonton(config)#dialer-list 2 protocol ip list 150

Points dialer list to ACL 150

Edmonton(config)#access-list 150 deny udp any any eq tftp

Denies TFTP traffic

Edmonton(config)#access-list 150 deny tcp any any eq telnet

Denies Telnet traffic

Edmonton(config)#access-list 150 permit ip any any

Permits everything else

Edmonton(config)#int bri 0


Edmonton(config-if)#dialer-group 2

Groups all dialer-list 2 statements together on this interface

Step 3: Configure DDR dialer information.


Edmonton(config)#username Calgary password academy

For PPP encapsulation with authentication across ISDN (optional)

Edmonton(config)#int bri 0


Edmonton(config-if)#encap ppp

Turns on PPP encapsulation

Edmonton(config-if)#ppp authentication chap

Turns on CHAP authentication

Edmonton(config-if)#dialer idle-timeout 150

Specifies the number of seconds after last interesting traffic is sent before the call terminates. Default is 120 seconds.

Edmonton(config-if)#dialer map ip name Calgary 5552000

Defines the following:

  • = IP address of next-hop router

  • Calgary = host name of remote router

  • 5552000 = number to dial to get there

CCNA Self-Study(c) CCNA Portable Command Guide
CCNA Portable Command Guide
ISBN: 1587201585
EAN: 2147483647
Year: 2006
Pages: 261
Authors: Scott Empson

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