Re: regexp - difference between ? and *

From: ismail el-shalh (ishelh_mdsa@yahoo.com)
Date: Fri Aug 11 2006 - 04:55:29 ART


Hi Chee,
   
  With BGP perspective, Usually you use ? in the regular expression if you want to match only one more AS in the path , but you do not know what that AS could be, for example it could be 200 , 250, 50 and so on, and you do not want to match more than one AS , in this case you should use "?".
   
   
  Again, think about it ? means Zero or one instance , which means either to match the absence of AS or to match the presence of one AS and stop there.
   
   
   
  * means is either no AS in the path or more than AS in the path , this is the reason we say Zero or more instances
   
  I prefer if you can revise IEWB , LAB 12, Task 5.8 , Brians did their best in a scenario with this keyword.
   
   
  Ismail El-Shalh
   
    

Chee Chew Leong <cleong3@csc.com> wrote:

  Could some one help me to understand what is the difference between ? and
* when I apply them particularly on bgp AS path matching?



This archive was generated by hypermail 2.1.4 : Fri Sep 01 2006 - 15:41:56 ART