bgp route-map

Mon Aug 25 19:30:01 UTC 2003

On Monday, August 25, 2003, at 3:00 PM, Haesu wrote:

>
> Yes, I've tried that too.. But what I am thinking of doing is, using a 
> route-map/bgp-announcement based version of building 'prefix-list' or 
> 'distribute-list' to decide whether to accept route or not..
>
> But as you said, I don't think that is possible heh..

Except that what you are proposing would allow your customer to 
announce 2 /16's just fine from within one of rob's bogon /8's, as the 
2 /16's wouldn't be in your rib.

>
> Thanks!
> -hc
>
> -- 
> Sincerely,
>   Haesu C.
>   TowardEX Technologies, Inc.
>   WWW: http://www.towardex.com
>   E-mail: haesu at towardex.com
>   Cell: (978) 394-2867
>
> On Mon, Aug 25, 2003 at 02:57:57PM -0400, ww at styx.org wrote:
>> 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
>> used.
>>
>> -w
>>
>> 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
>>> not...
>>>
>>> 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.
>>>
>>> Thanks!
>>>
>>> -hc
>>>
>>> --  
>>> Sincerely,
>>>   Haesu C.
>>>   TowardEX Technologies, Inc.
>>>   WWW: http://www.towardex.com
>>>   E-mail: haesu at towardex.com
>>>   Cell: (978) 394-2867
>
>
--
Matt Levine <matt at deliver3.com>
"The Trouble with doing anything right the first time is that nobody 
appreciates how difficult it was."  -BIX