From: Bell, Mark (Houston) (m.bell@xxxxxxxxxx)
Date: Tue Oct 03 2000 - 09:59:04 GMT-3
I added 6.0.0.0/8 to the router 10.20.1.2 (r2) so that it appears in this
router's (r1) BGP table (see below). Even after 11.1.0.0/16 disappears, as
illustrated from the cut-and-paste, 6.0.0.0/8 still does not appear in the
BGP table of 10.10.1.3 (r3). The configuration is the same as what I posted
previously.
r1#sh ip bgp
BGP table version is 15, local router ID is 10.20.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i -
internal
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 4.0.0.0/24 10.10.1.3 0 2 1 ?
*> 5.0.0.0/24 10.10.1.3 0 2 1 ?
*>i6.0.0.0 10.20.1.2 0 100 0 i
*> 200.200.200.0 10.10.1.3 0 2 1 ?
r3#sh ip bgp
BGP table version is 8, local router ID is 10.31.1.33
Status codes: s suppressed, d damped, h history, * valid, > best, i -
internal
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 4.0.0.0/24 10.41.1.1 10 0 1 ?
*> 5.0.0.0/24 10.41.1.1 10 0 1 ?
*> 200.200.200.0 10.41.1.1 0 0 1 ?
-----Original Message-----
From: Mark Lewis [mailto:markl11@hotmail.com]
Sent: Tuesday, October 03, 2000 06:39
To: m.bell@wilcom.com; ccielab@groupstudy.com
Subject: RE: Conditional BGP Advertisements
Yup, the 'backup' route has to be also present in the bgp table before it
can be advertised in the absence of the primary route.
To confirm that everything is working as planned, use the 'sh ip bgp neigh'
command and look for the part of the output which shows the status of the
advertise map.
Hope that helps,
Mark
>From: "Bell, Mark (Houston)" <m.bell@wilcom.com>
>Reply-To: "Bell, Mark (Houston)" <m.bell@wilcom.com>
>To: "CCIE Study Group (E-mail)" <ccielab@groupstudy.com>
>Subject: RE: Conditional BGP Advertisements
>Date: Mon, 2 Oct 2000 21:53:11 -0500
>
>I have attempted to configure a conditional advertisement in my network
>using the following config:
>
>router bgp 3
> no synchronization
> neighbor 10.10.1.3 remote-as 2
> neighbor 10.10.1.3 advertise-map BACKUP non-exist-map BACKUP2
> neighbor 10.10.1.5 remote-as 3
> neighbor 10.10.1.5 route-reflector-client
> neighbor 10.20.1.2 remote-as 3
> neighbor 10.20.1.2 route-reflector-client
>!
>ip classless
>no ip http server
>ip as-path access-list 1 permit _\(65005\)$
>!
>access-list 1 permit 6.0.0.0
>access-list 2 permit 11.1.0.0
>route-map BACKUP permit 10
> match ip address 1
>!
>route-map ASPATH permit 10
> match as-path 1
> set local-preference 500
>!
>route-map BACKUP2 permit 10
> match ip address 2
>
>When I go to the router 10.10.1.5 that advertises 11.1.0.0/16 and shut down
>it's link to this router, 11.1.0.0/16 disappears from the BGP table as
>expected. If I understand conditional advertisements correctly, the router
>should begin advertising 6.0.0.0/8 to 10.10.1.3 because 11.1.0.0/16 is
>gone.
>The problem is, 6.0.0.0/8 never shows up anywhere.
>
>Does the backup route have to be present in the BGP table prior to the
>monitored route disappearing or will it be injected into the BGP table only
>when necessary? Are there any restrictions as to whether the monitored or
>backup route must be learned via iBGP or eBGP?
>
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