Cisco Certified Expert

Example

The figure demonstrates the impact that overlapping destination patterns have on the callrouting decision. In example 1, the destination pattern in dial-peer 1 is a subset of the destination pattern in dial-peer 2. Because the router matches one digit at a time against available dial peers, an exact match will always occur on dial-peer 1, and dial-peer 2 will never be matched.

In example 2, the length of the destination patterns in both dial peers is the same. Dial-peer 2 has a more specific value than dial-peer 1, so it will be matched first. If the path to IP address 10.18.0.2 is unavailable, dial-peer 1 will be used.

Matching Destination Patterns

Dialed Digits	Destination Pattern	Dialed Digits Collected
5551234	5	5551234
5551234	555	5551234
5551234	555	555
5551234	555T	5551234

In the first row of the table, the destination pattern specifies a seven-digit string. The first digit must be a five, and the remaining six digits can be any valid digits. All seven digits must be entered before the destination pattern is matched.

In the second row, the destination pattern specifies a seven-digit string. The first three digits must be 555, and the remaining four digits can be any valid digits. All seven digits must be entered before the destination pattern is matched.

In the third row, the destination pattern specifies a three-digit string. The dialed digits must be exactly 555. When the user begins to dial the seven-digit number, the destination pattern matches after the first three digits are entered. The router then stops collecting digits and places the call. If the call is set up quickly, the answering party at the other end may hear the remaining four digits as the user finishes dialing the string. After a call is set up, any dual-tone multifrequency (DTMF) tones are sent through the voice path and played out at the other end.

In the last row, the destination pattern specifies a variable-length digit string that is at least three digits long. The first three digits must be exactly 555, and the remaining digits can be any valid digits. The 'T' tells the router to continue collecting digits until the interdigit timer expires. The router stops collecting digits when the timer expires, or when the user presses the pound (#) key.

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