From: Shamin (ccie.xpert@gmail.com)
Date: Fri Oct 26 2007 - 04:04:01 ART
Hi all,
The solution is good. But in the actual lab if they do not allow you to do
a static route,
then this solution will it help.
Regards
Shamin
On 10/25/07, Koen Zeilstra <koen@koenzeilstra.com> wrote:
>
> 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 -----
> >>>>
> >>>> _____________________________________________________________________
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