Re: bgp conditional route advertisement

Thanks Tony,

I have not labbed this up but just a thought and I could be wrong.. what
if OSPF is advertising the route to BGP and this is how BGP router knows
the route and this is why it advertises the route, and if we configure
max-metric router-lsa wait-for-bgp on the OSPF router advertising the
route, this will configure the router to advertise a maximum metric until
BGP routing tables has converged, I believe it will wait for 10 minutes. It
may work but it needs to be labbed up. Thinking out loud......

On Mon, Sep 16, 2013 at 11:15 AM, Tony Singh <mothafungla_at_gmail.com> wrote:

>
> Thanks Narbik nice and clear, I think the reservation that Balaji has it
> that when the bgp process resets it causes host route 3.3.3.3 to be
> advertised prior to bgp receiving all networks into its rib to me this is
> an order of ops where bgp rib will install host route to 1.1.1.1 into
> global and not yet learning the 2.2.2.2 route.
>
> Balaji if you're testing I'd imagine not much traffic being forwarded to
> the 3.3.3.3 network prior to the route being withdrawn.
>
> The answer is this is just the way the feature works.
>
> --
> BR
>
> Tony
>
> Sent from my iPad
>
> On 16 Sep 2013, at 18:47, Narbik Kocharians <narbikk_at_gmail.com> wrote:
>
> Have a look at this lab that I wrote, it might help you:
>
> http://micronics.nl/BGP-Conditional-Adv.pdf
>
>
> On Mon, Sep 16, 2013 at 10:12 AM, Tony Singh <mothafungla_at_gmail.com>wrote:
>
>> Hi Balaji
>>
>> This is a good question one which I have been scratching my head over,
>> can you confirm if this is in your production environment or is it on
>> gns/IOU or home lab if so please confirm platform/IOS version
>>
>> --
>> BR
>>
>> Tony
>>
>> Sent from my iPad
>>
>> On 4 Sep 2013, at 14:58, BALAKRISHNAN Balaji <
>> Balaji.BALAKRISHNAN_at_swift.com> wrote:
>>
>> > All,
>> >
>> >
>> >
>> > Any suggestion ?.. Configuration is as below
>> >
>> >
>> >
>> > ip route 3.3.3.3 255.255.255.255 1.1.1.1
>> >
>> >
>> >
>> > Router bgp 65000
>> >
>> > Network 3.3.3.3 mask 255.255.255.255
>> >
>> > neighbour 192.168.1.1 remote-as 65001
>> >
>> > neighbour 192.168.1.1 advertise-map ADVERTISE non-exist-map NONEXIST
>> >
>> > !
>> >
>> > Route-map ADVERTISE permit 10
>> >
>> > Match ip address 50
>> >
>> > !
>> >
>> > Access-list 50 permit 3.3.3.3
>> >
>> > !
>> >
>> > Route-map NONEXIST permit 10
>> >
>> > Match ip address 30
>> >
>> > !
>> >
>> > Access-list 30 permit 2.2.2.2
>> >
>> > !
>> >
>> >
>> >
>> > Thanx
>> >
>> > Balaji
>> >
>> >
>> >
>> > From: BALAKRISHNAN Balaji
>> > Sent: Tuesday, September 03, 2013 5:31 PM
>> > To: ccielab_at_groupstudy.com
>> > Subject: bgp conditional route advertisement
>> >
>> >
>> >
>> > Hello all,
>> >
>> >
>> >
>> > I have a scenario that I am struggling to address a specific issue and
>> would
>> > like to hear your recommendation
>> >
>> >
>> >
>> > Announce the route 3.3.3.3 to the bgp neighbour only under the following
>> > condition on the routes it receives from the backbone
>> >
>> >
>> >
>> > - Only if it has valid 1.1.1.1/32 route on the bgp table
>> but no
>> > valid route for 2.2.2.2/32
>> >
>> >
>> >
>> > It works fine under the normal situation when both 1.1.1.1 and 2.2.2.2
>> exist
>> > in the bgp table ( meaning conditional route does not get triggered) .
>> But
>> > when the router bounces its bgp connection to the backbone, it learns
>> the
>> > route 1.1.1.1/32 fraction of a second earlier than 2.2.2.2/32.. It
>> causes
>> > the conditional advertisement to kick in momentarily before withdrawing
>> > immediately after which is causing some undesirable instability in the
>> > network.. Can you recommend any work around to resolve this issue.
>> >
>> >
>> >
>> > Rgds
>> >
>> > Balaji
>> >
>> >
>> > Blogs and organic groups at http://www.ccie.net
>> >
>> > _______________________________________________________________________
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>>
>>
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>>
>>
>>
>>
>>
>>
>>
>
>
> --
> *Narbik Kocharians
> *CCSI#30832, CCIE# 12410 (R&S, SP, Security)
> *www.MicronicsTraining.com* <http://www.micronicstraining.com/>
> Sr. Technical Instructor
> YES! We take Cisco Learning Credits!
> A Cisco Learning Partner
>
>

--
*Narbik Kocharians
*CCSI#30832, CCIE# 12410 (R&S, SP, Security)
*www.MicronicsTraining.com* <http://www.micronicstraining.com/>
Sr. Technical Instructor
YES! We take Cisco Learning Credits!
A Cisco Learning Partner
Blogs and organic groups at http://www.ccie.net