Reason for using "dialer map .." cmd

[mnlatif]

Hi,

I am configuring a Cisco 1700 router to dialin to cisco 2600 using ISDN. In all the sample configs, i have seen the command "dialer map ip x.x.x. name ir-isdn <phone number>" being used on both ends.

For the dialout router , i can understand that this is needed to dial to the correct number.

However what is the purpose for this command on the other router (that is accepting the dial-in) ?

I tried to configure the dial-in server without this command and it still worked, so i am not sure about the significance ?

\\ Naman

[mark-obrien]

Naman,

At the end that accepts the call, the purpose of the dialer map is for the router to map the name or caller ID to the IP address of the caller. Without it, the called end may have a route pointing to an IP address that is attached to the dialer interface. The router will route packets to that interface, but if it doesn't know which user (i.e. name or caller ID) is associated with that address, an encapsulation failure will result.

Hope this helps,

Mark

[mnlatif]

Thanks Mark.

Will this also be needed (i.e. "dialer map.." statement )when using dynamic routing ? E.g. when EIGRP is enabled on the dialer interface.

Thanks \\ Naman

[vcjones]

> Will this also be needed (i.e. "dialer map.." st atement )when using dynamic routing ?

> E.g. when EIGRP is enabled on the dialer interface.

Yes.

[dbellazetin]

You only need to have a dialer map statement on the dialing side of the connection. If both sides need to be able to dial each other than the command is necessary on both ends.

If you use the "dialer map" command you will need to remember to include the "broadcast" keyword which will allow routing updates to flow across the interface.

This also brings up the fact that now eigrp, or any other dynamic routing protocol for that matter will be able to trigger a call on your ISDN line which may not be desirable depending on how you are being billed for the line.

Make sure that you have an access list bound to your dialer list that specifically states what traffic can place a call. This way once the call is up eigrp will do its thing and when the call drops eigrp will remove the routes it has learned.

Daniel