From: R.J.Neill Craven (ncraven@cravenworks.com)
Date: Thu Sep 04 2003 - 14:51:22 GMT-3
When digits arrive one at a time (as from an FXS port), the
destination pattern matching algorithm is executed as each new digit
arrives. If the process has received enough digits to match at least
one destination pattern, an action is taken. The action is based on
the "best" match rules. By default the "best match" is the one with
the most matching digits. (See below for a more correct definition of
"best".) If no match is found the process waits for the next digit
and repeats.
When the digits arrive in a "batch" (as in a PLAR, VoIP, VoFR, VoATM,
or csim), all digits are sent to the algorithm in one go; they are
NOT sent one at a time. All patterns are compared to the "batched"
digits and the best match is, once again, the one with the most
matching digits (again subject to my clarification below). Notice in
this case, because shorter strings are NOT tried first, the best
match will be the longest destination pattern even though shorter
destination patterns may match some of the leading digits.
Regarding the definition of "best"...
If a comparison of the dial string matches only one destination
pattern, the action of the dial peer is taken. If more than one match
is the result, the "best" must be selected. By default, the "best"
match is defined as the one with the most matching digits (a wild
card "." does not count as a matching digit). If two or more dial
peers result in matching the same number of digits, the dial peer
preference is used. If the preference is the same, the dial peers are
selected randomly. You can change this behaviour by selecting a
different value for the "dial-peer hunt" command. For example, you
would use "dial-peer hunt 3" to change the "best" match to be
preference, then longest match, then least recent used. Notice, in no
case, is the decision based on the order in which the dial peers were
created.
By the way, the rules for "best" on the CallManger are different.
Because CCM is not an issue for the R&S lab, I'll leave that for a
separate discussion.
Cheers,
Neill
At 11:22 AM -0400 4/9/03, Jonathan V Hays wrote:
>So, you are saying that the CSIM Start emulation does not match the
>behavior of a real phone!?
>
>Hmm. From Brian Dennis' output below it sort of looks like the phone is
>doing a "shortest match"!? Well, that is similar to how a POTS phone
>works: once you have dialed your 7 digits for a local call, the phone
>system ignores any additional digits punched in. And according to your
>example, once the VOIP router gets a "1" from the phone it has a match
>and uses dial-peer 1.
>
>On the surface this seems to contradict what Brian McGahan was saying
>earlier in this thread about the *longer* match for destination patterns
>being preferred. Evidently that is only true for CSIM Start? Or only
>true for a choice between a 'real' phone number and a wildcard pattern?
>
>Please clarify.
>
>Does the order of the dial-peer statements makes a difference (like it
>does in an access list)? Suppose the order were reversed. Would the
>phone then match dial-peer 1 for the "12" pattern?
>
>dial-peer voice 1 voip
> destination-pattern 12
> session target ipv4:10.0.0.1
>!
>dial-peer voice 2 voip
> destination-pattern 1
> session target ipv4:10.0.0.1
>
>Obviously voice is not my strong point ....
>
>Jonathan
>
>!-----Original Message-----
>From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
>Brian Dennis
>Sent: Thursday, September 04, 2003 12:07 AM
>To: 'Alec'
>Cc: ccielab@groupstudy.com
>Subject: RE: Destination pattern symbols
>
>
>Alec,
>Here is how they would match.
>
>CSIM Start
>1) "1" - dial-peer 1
>2) "12" - dial-peer 2
>3) "123" - dial-peer 2
>
>Phone
>1) "1" - dial-peer 1
>2) "12" - dial-peer 1
>3) "123" - dial-peer 1
>
>Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)
>bdennis@internetworkexpert.com
>Toll Free: 877-334-8987
>Direct: 775-745-6404 (Outside the US and Canada)
>Internetwork Expert, Inc.
>http://www.InternetworkExpert.com
>
>-----Original Message-----
>From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
>Alec
>Sent: Wednesday, September 03, 2003 8:14 PM
>To: Brian McGahan; 'Paul Chen'; ccielab@groupstudy.com
>Subject: Re: Destination pattern symbols
>
>thanks Brian. If I have the following dial-peer voice command, which
>one
>will be used after I pressed
>
>1) "1"
>2) "12"
>3) "123"
>
>in a real phone and csim ? Thanks.
>
>dial-peer voice 1 voip
> destination-pattern 1
> session target ipv4:10.0.0.1
>!
>dial-peer voice 2 voip
> destination-pattern 12
> session target ipv4:10.0.0.1
>!
>dial-peer voice 3 voip
> destination-pattern .
> session target ipv4:20.0.0.2
>!
>dial-peer voice 4 voip
> destination-pattern .T
> session target ipv4:20.0.0.2
>
>
>----- Original Message -----
>From: "Brian McGahan" <bmcgahan@internetworkexpert.com>
>To: "'Alec'" <clapun@graduate.hku.hk>; "'Paul Chen'"
><cpjchen@starhub.net.sg>; <ccielab@groupstudy.com>
>Sent: Thursday, September 04, 2003 2:20 AM
>Subject: RE: Destination pattern symbols
>
>
>> Alec,
>>
>> It will only match a single character then. As soon as the
>> single character is input, the router will do call setup. This will
>not
>> be true for the 'csim start' command though, since the string is sent
>> all at once. From an actual phone though, the string is sent 1
>> character at a time.
>>
>> HTH
>>
>> Brian McGahan, CCIE #8593
>> bmcgahan@internetworkexpert.com
>>
>> Internetwork Expert, Inc.
>> http://www.InternetworkExpert.com
>> Toll Free: 877-334-8987
>> Direct: 708-362-1418 (Outside the US and Canada)
>>
>>
>> -----Original Message-----
>> From: Alec [mailto:clapun@graduate.hku.hk]
>> Sent: Wednesday, September 03, 2003 10:24 AM
>> To: Brian McGahan; 'Paul Chen'; ccielab@groupstudy.com
>> Subject: Re: Destination pattern symbols
>>
>> So what if I use destination-pattern . for voice default route ?
>What's
>> the
>> difference with .T ?
>>
>> ----- Original Message -----
>> From: "Brian McGahan" <bmcgahan@internetworkexpert.com>
>> To: "'Paul Chen'" <cpjchen@starhub.net.sg>; <ccielab@groupstudy.com>
>> Sent: Wednesday, September 03, 2003 4:22 PM
>> Subject: RE: Destination pattern symbols
>>
>>
>> > Paul,
>> >
>> > T actually means interdigit timeout. The default interdigit
>> > timeout is 10 seconds. Each time you dial a digit, the router is
>> going
>> > to wait 10 seconds before doing call setup. After 10 seconds have
>> > expired, the router assumes that what you have entered so far is the
>> > complete dial string, and does call setup on those digits. You can
>> > modify the interdigit timeout with the voice-port command 'timeouts
>> > inter-digit'.
>> >
>> > The combination of the . (any single character) and the T (wait
>> > for additional characters) effectively defines a default route for
>> > voice.
>> >
>> >
>> > HTH,
>> >
>> > Brian McGahan, CCIE #8593
>> > bmcgahan@internetworkexpert.com
>> >
>> > Internetwork Expert, Inc.
>> > http://www.InternetworkExpert.com
>> > Toll Free: 877-334-8987
>> > Direct: 708-362-1418 (Outside the US and Canada)
>> >
>> >
>> > -----Original Message-----
>> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
>> Of
>> > Paul Chen
>> > Sent: Wednesday, September 03, 2003 3:05 AM
>> > To: ccielab@groupstudy.com
>> > Subject: Destination pattern symbols
>> >
>> > Hi,
>> >
>> >
>> >
>> > Could someone please explain to me what these symbols mean:
>> >
>> >
>> >
>> > Destination-pattern .T
>> >
>> >
>> >
>> > A dot implies a single character right ?
>> >
>> >
>> >
>> > The T symbol implies a variable length dial string.
>> >
>> >
>> >
>> > Does the combination of the 2 symbols mean dial any number ?
>> >
>> >
>> >
>> > Thanks.
>> >
>> > Paul
>> >
>> >
>> >
>>
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