From: Koen Zeilstra (koen@koenzeilstra.com)
Date: Fri Oct 26 2007 - 03:33:50 ART
As an addendum for those who are worried about the default route which
can be received via other ways resulting in advertising the default on
our router even if we don't want to.
Use a (dirty) bogus route to get the AND function
track 1 list boolean and
object 2
object 3
!
track 2 ip route 1.1.1.0 255.255.255.0 reachability
!
track 3 ip route 2.2.2.0 255.255.255.0 reachability
!
interface Loopback1
ip address 1.1.1.1 255.255.255.0
!
interface Loopback2
ip address 2.2.2.2 255.255.255.0
!
interface FastEthernet0/0
ip address 100.100.100.1 255.255.255.0
duplex auto
speed auto
!
router bgp 100
no synchronization
bgp log-neighbor-changes
neighbor 100.100.100.2 remote-as 100
neighbor 100.100.100.2 default-originate route-map CHECK_DEFAULT
no auto-summary
!
ip route 123.123.123.123 255.255.255.255 Null0 track 1
!
ip prefix-list BOGUS seq 5 permit 123.123.123.123/32
!
route-map CHECK_BOGUS permit 10
match ip address prefix-list BOGUS
!
Quoting Koen Zeilstra <koen@koenzeilstra.com>:
> This works for me. Thanks!!!
>
>
>
> Quoting Con Spathas <con@spathas.net>:
>
>> I was thinking about the BGP config I initially tested with and I really
>> didn't like it tbh...
>> I've quickly labbed this up and appears to have the same functionality in
>> conjunction with the tracked obbjects etc...
>> It's alot safer than using a network statement...
>>
>> Just modified the bgp config and added a prefix-list/route-map combo.
>>
>> ---------------------
>> !
>> track 1 list boolean and
>> object 2
>> object 3
>> !
>> track 2 ip route 1.1.1.0 255.255.255.0 reachability
>> !
>> track 3 ip route 2.2.2.0 255.255.255.0 reachability
>> !
>> interface Loopback1
>> ip address 1.1.1.1 255.255.255.0
>> !
>> interface Loopback2
>> ip address 2.2.2.2 255.255.255.0
>> !
>> interface FastEthernet0/0
>> ip address 100.100.100.1 255.255.255.0
>> duplex auto
>> speed auto
>> !
>> router bgp 100
>> no synchronization
>> bgp log-neighbor-changes
>> neighbor 100.100.100.2 remote-as 100
>> neighbor 100.100.100.2 default-originate route-map CHECK_DEFAULT
>> no auto-summary
>> !
>> ip route 0.0.0.0 0.0.0.0 Null0 track 1
>> !
>> ip prefix-list DEFAULT seq 5 permit 0.0.0.0/0
>> !
>> route-map CHECK_DEFAULT permit 10
>> match ip address prefix-list DEFAULT
>> !
>>
>> -----Original Message-----
>> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
>> Usankin, Andrew
>> Sent: Tuesday, 23 October 2007 18:42
>> To: ccielab@groupstudy.com
>> Subject: RE: RE: conditional default advertising in BGP with multiple routes
>> tomonitor
>>
>> Works like a charm Con! Just got it labbed.
>>
>> You have cracked this one :)
>> I'm taking my word back about "default-info originate", you don't need that
>> if you use "network 0.0.0.0".
>>
>> Andrew
>>
>> -----Original Message-----
>> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
>> Usankin, Andrew
>> Sent: Tuesday, October 23, 2007 10:24 AM
>> To: ccielab@groupstudy.com
>> Subject: RE: RE: conditional default advertising in BGP with multiple routes
>> tomonitor
>>
>>
>> Perfect! I'm going to lab it right away to se how it works.
>>
>> By the way you missed one command in router bgp 100:
>> default-information originate.
>>
>> Anyway thanks for advise Con!
>>
>> Andrew
>>
>> -----Original Message-----
>> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Con
>> Spathas
>> Sent: Tuesday, October 23, 2007 2:31 AM
>> To: 'Koen Zeilstra'; 'Benedict Munyao'
>> Cc: ccielab@groupstudy.com
>> Subject: RE: RE: conditional default advertising in BGP with multiple routes
>> tomonitor
>>
>> Thought I'd kick my $0.02 in - imho I don't think I'd ever use this possible
>> solution in production but kinda fun in a lab - however here
>> goes:
>>
>> I setup BGP peering with 2 routers - R1 <-> R2.
>> The goal - have R1 only send R2 a 0/0 via BGP if 2 seperate routes were
>> reachable on R1.
>>
>> On R1 I setup a boolean track and added a static route for 0/0 to null
>> watching the boolean track.
>>
>> !
>> track 1 list boolean and
>> object 2
>> object 3
>> !
>> ip route 0.0.0.0 0.0.0.0 Null0 track 1
>> !
>>
>> The 2 track objects (2 & 3) are just 2 connected interfaces - but I suppose
>> you could track anything in the the routing table:
>>
>> !
>> track 2 ip route 1.1.1.0 255.255.255.0 reachability
>> !
>> track 3 ip route 2.2.2.0 255.255.255.0 reachability !
>>
>> Finally I setup BGP - the iffy part here is getting 0/0 into the bgp table
>> so I added the 0.0.0.0 network to keep it simple.
>>
>> !
>> router bgp 100
>> no synchronization
>> bgp log-neighbor-changes
>> network 0.0.0.0
>> neighbor 100.100.100.2 remote-as 1000
>> no auto-summary
>> !
>>
>> Careful filtering would need to be in place to even consider doing something
>> like this in production.
>> Imagine the potential havoc if you unleashed a 0/0 into BGP!!!! <grin>
>>
>> So now if I kill either of the 1.1.1.0/24 or the 2.2.2.0/24 networks on
>> R1 - the static 0/0 route will be withdrawn from the routing table and thus
>> the bgp table.
>> This in turn will cause BGP to withdraw the 0/0 route to R2. Therefore both
>> tracked routes must be reachable before the 0/0 gets sent to the neighbor.
>>
>> Anyhow with the limited testing I did it seems like a possible solution to
>> the AND problem.
>>
>> Cheers.
>>
>>
>> -----Original Message-----
>> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Koen
>> Zeilstra
>> Sent: Tuesday, 23 October 2007 07:38
>> To: Benedict Munyao
>> Cc: ccielab@groupstudy.com
>> Subject: Re: RE: conditional default advertising in BGP with multiple routes
>> tomonitor
>>
>> Correct. However for watching two routes this isn't a solution.
>>
>> Two match clauses in different subblocks cause the default to be announced
>> when the first clause is a match. What we need is de default to be announced
>> when BOTH match clauses have a positive match.
>>
>> Quoting Benedict Munyao <bmunyao@gmail.com>:
>>
>>> The first solution examined in this thread included using "neighbor
>>> default-originate route-map" command. The Doccd clarifies why it only
>>> uses the "or" logic when comparing the two ACLs:
>>>
>>> http://www.cisco.com/univercd/cc/td/doc/product/software/ios124/124cr/
>>> hirp_r/rte_pih.htm#wp1123413
>>>
>>> "Like matches in the same route map subblock are filtered with "or"
>>> semantics. If any one match clause is matched in the entire route map
>>> subblock, this match is treated as a successful match. Dissimilar
>>> match clauses are filtered with "and" semantics. So dissimilar matches
>>
>>> are filtered logically. If the first set of conditions is not met, the
>>
>>> second match clause is filtered."
>>>
>>> HTH
>>> Benedict Munyao
>>>
>>>
>>>
>>> On 10/19/07, Koen Zeilstra <koen@koenzeilstra.com> wrote:
>>>>
>>>> Balmik has email this nice solution to me which I would like to share
>>
>>>> with the group.
>>>>
>>>> Balmik, I hope you don't mind that I send this to the group.
>>>>
>>>> I have tested this on my lab and the results in various situations on
>>
>>>> different platforms
>>>>
>>>> Situation 1. It only checks line 10 of the route-map, and ignores the
>>
>>>> rest.
>>>> Situation 2. It does a OR. So both routes have to dissapear to remove
>>
>>>> the default instead of one.
>>>>
>>>> From:
>>>>
>>>> http://www.cisco.com/en/US/products/ps6566/products_feature_guide0918
>>>> 6a00801a7f7a.html#wp1038479
>>>>
>>>> I read that outbound BGP route-maps only are supported. I would say
>>>> this is a outbound BGP route-map. The only different from standard
>>>> advertisement is de conditional default. Maybe it is only intended
>>>> for match and set operations on advertised routes.
>>>>
>>>>
>>>>
>>>> ----- Forwarded message from balmik@staff.iinet.net.au -----
>>>> Date: Fri, 19 Oct 2007 14:07:49 +0800
>>>> From: Balmik Soin <balmik@staff.iinet.net.au>
>>>> Reply-To: Balmik Soin <balmik@staff.iinet.net.au>
>>>> Subject: RE: conditional default advertising in BGP with multiple
>>>> routes tomonitor
>>>> To: Koen Zeilstra <koen@koenzeilstra.com>, Bob Sinclair
>>>> <bob@bobsinclair.net>
>>>> Cc: Saul Arjona <saul.arjona.bueno@gmail.com>
>>>>
>>>> (Removing CCIE groupstudy list for this email)
>>>>
>>>> I'm not able to test this at the moment, but can I suggest you try a
>>>> CONTINUE route-map statement to try and get an AND working?
>>>>
>>>> Something like a
>>>>
>>>> Route-map XXX permit 10
>>>> Match ip address prefix-list 1
>>>> Continue 30
>>>>
>>>> Route-map XXX deny 20
>>>>
>>>> Route-map XXX permit 30
>>>> Match ip address prefix-list 2
>>>>
>>>> I don't know if "continue" will work for these kinds of route-maps,
>>>> but it's worth a try - if it works, then you can post it to
>>>> GroupStudy. I just didn't want to post a "perhaps" email to the group
>>
>>>> without testing it, and ending up wasting people's time :)
>>>>
>>>> --
>>>> Balmik Soin
>>>> Voice Network Engineer Desk: +61-8-9213-1370
>>>> Voice Engineering - Network Services Mobile: +61-414-429-266
>>>> iiNet Limited balmik@staff.iinet.net.au
>>>>
>>>>
>>>>> -----Original Message-----
>>>>> From: Koen Zeilstra [mailto:koen@koenzeilstra.com]
>>>>> Sent: Friday, 19 October 2007 1:14 PM
>>>>> To: Bob Sinclair
>>>>> Cc: Balmik Soin; Saul Arjona; ccielab@groupstudy.com
>>>>> Subject: Re: conditional default advertising in BGP with multiple
>>>> routes
>>>>> tomonitor
>>>>>
>>>>> Yes we do have a solution for the OR, now we still need a solution
>>>>> for the AND function. Matching both routes for one descision.
>>>>>
>>>>>
>>>>>
>>>>> Quoting Bob Sinclair <bob@bobsinclair.net>:
>>>>>
>>>>> > Koen Zeilstra wrote:
>>>>> >> Correct. The conditions are never met for ACL 10.
>>>>> >>
>>>>> >> I have labbed the original and this solution up, no AND just OR.
>>>>> >>
>>>>> > Absolutely right! I stand corrected. So do we have a solution
>>>>> > for
>>>> OR?
>>>>> >
>>>>> > --
>>>>> >
>>>>> >
>>>>> > Bob Sinclair CCIE 10427 CCSI 30427 www.netmasterclass.net
>>>>>
>>>>
>>>>
>>>>
>>>> ----- End forwarded message -----
>>>>
>>>> _____________________________________________________________________
>>>> __ Subscription information may be found at:
>>>> http://www.groupstudy.com/list/CCIELab.html
>>>
>>> ______________________________________________________________________
>>> _ Subscription information may be found at:
>>> http://www.groupstudy.com/list/CCIELab.html
>>
>> _______________________________________________________________________
>> Subscription information may be found at:
>> http://www.groupstudy.com/list/CCIELab.html
>>
>> _______________________________________________________________________
>> Subscription information may be found at:
>> http://www.groupstudy.com/list/CCIELab.html
>>
>> The content contained in this electronic message is not intended to
>> constitute formation of a contract binding TWTC. TWTC will be contractually
>> bound only upon execution, by an authorized officer, of a contract including
>> agreed terms and conditions or by express application of its tariffs.
>>
>> This message is intended only for the use of the individual or entity to
>> which it is addressed. If the reader of this message is not the intended
>> recipient, or the employee or agent responsible for delivering the message
>> to the intended recipient, you are hereby notified that any dissemination,
>> distribution or copying of this message is strictly prohibited. If you have
>> received this communication in error, please notify us immediately by
>> replying to the sender of this E-Mail or by telephone.
>>
>> _______________________________________________________________________
>> Subscription information may be found at:
>> http://www.groupstudy.com/list/CCIELab.html
>>
>> The content contained in this electronic message is not intended to
>> constitute formation of a contract binding TWTC. TWTC will be contractually
>> bound only upon execution, by an authorized officer, of a contract including
>> agreed terms and conditions or by express application of its tariffs.
>>
>> This message is intended only for the use of the individual or entity to
>> which it is addressed. If the reader of this message is not the intended
>> recipient, or the employee or agent responsible for delivering the message
>> to the intended recipient, you are hereby notified that any dissemination,
>> distribution or copying of this message is strictly prohibited. If you have
>> received this communication in error, please notify us immediately by
>> replying to the sender of this E-Mail or by telephone.
>>
>> _______________________________________________________________________
>> Subscription information may be found at:
>> http://www.groupstudy.com/list/CCIELab.html
>>
>> _______________________________________________________________________
>> Subscription information may be found at:
>> http://www.groupstudy.com/list/CCIELab.html
>
> _______________________________________________________________________
> Subscription information may be found
> at:http://www.groupstudy.com/list/CCIELab.html
This archive was generated by hypermail 2.1.4 : Fri Nov 16 2007 - 13:11:18 ART