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Re: bgp route-map
From: ww () styx org
Date: Mon, 25 Aug 2003 14:57:57 -0400

I don't think what you are suggesting is directly possible, although I can think of 
something that accomplishes the same thing, and only requires extra configuration on 
the peering session with the route server. 
For prefixes recieved from the bogon route server, apply a route map that will (1) 
send traffic to a Null0 bit sink and (2) set the local preference for these routes to a 
value suitably large so that the same prefixes learned from other peers never get 
On Mon, 25 Aug 2003 14:39:59 -0400, Haesu wrote 
Hi all, 
Wondering if anyone would know whether such feature in IOS exists or  
Most of the time, people use route-maps on bgp neighbors or peer- 
groups to set an attribute,etc on a prefix that is being announced  
OUTbound or INbound. 
However: On prefixes being announced to me INBOUND, is there a  
feature  to set in route-map so that it checks whether the  
advertised prefix is already existing in local RIB? 
Like for example, I am one of the users who receive bogon  
advertisements from Rob's route-server. 
Now, when I receive prefixes either from my upstream AS or my  
customers doing bgp with me, I can setup a route-map on the neighbor  
so that it compares the prefix being announced by neighborAS with  
existing Rob's bogon prefix in the RIB with bogon route-server  
community 65333:888. 
If the prefix being announced gets a match with existing prefix with  
65333:888 already in the router, the route-map would cause a DENY.  
Thus, making Rob's bogon announcement from his route-server, a bogon  
route filtering list for me to use on my customers/peers.. 
If you are not understanding what I am saying, feel free to yell at  
me to clear up.. 
This would make it much easier to create dynamic bgp-based route  
filtering list in my opinion... I am not here to discuss the  
feasibility of whether doing or inventing this dynamic method of  
filtering bgp routes; I am rather asking this question to see if  
anyone is doing something similar to this as it may be useful. 
  Haesu C. 
  TowardEX Technologies, Inc. 
  WWW: http://www.towardex.com 
  E-mail: haesu () towardex com 
  Cell: (978) 394-2867 

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