How to establish BGP Neighbourship without receiving BGP routes ?

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Sep 10th, 2014
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Hi All,

I would like to establish BGP Neighbourship between my internet router and ISP router.

However I would not like my internet router to receive millions of bgp routes from the ISP router but my inside users should access internet via my internet router.

Kindly suggest how to do it.

Regards,

Mitesh Manwatkar.

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Akash Agrawal Wed, 09/10/2014 - 22:46
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Hi Mitesh,

 

You can ask your ISP to advertise just a default route. On your internet router apply inbound route-map as well to permit just default route.

 

-- Pls dont forget to rate helpful posts--

Regards,

Akash

Mitesh Manwatkar Wed, 09/10/2014 - 22:53
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Hi,

We are also having some servers which must be reached by rest of the world on internet.

Will it help in such scenario?

Regards.

Akash Agrawal Wed, 09/10/2014 - 23:01
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You can advertise your all internal routes to ISP, so that outside world can reach to your internal servers ,that is for reverse traffic. But to reach internet you just need a default route. You can contact your ISP with this requirement, they will help you out.

 

 

Richard Burts Thu, 09/11/2014 - 05:09
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It may be helpful to remember that in BGP learning routes from a neighbor and advertising routes to the neighbor are separate operations and are controlled independently. As Akash has explained you can configure a route map or a distribute list to control what routes you learn from your neighbor and have no effect of what you advertise. Appropriate network statements or redistribute statements allow you to advertise routes to your neighbor and have no effect on what you learn from the neighbor.

 

HTH

 

Rick

Mitesh Manwatkar Wed, 09/17/2014 - 04:51
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Hi,

I would like to know the command which ISP would use to advertise default route towards my internet router.

Regards.

Richard Burts Wed, 09/17/2014 - 06:16
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Mitesh

 

There are several commands which an ISP might use to advertise a default route to you.

- there is a command under router bgp of default-information originate which will generate a default route to be advertised to neighbors.

- there is a parameter of the neighbor command neighbor 1.1.1.1 default-originate  which will generate a default route for that specific neighbor.

- the ISP might use a network statement or use redistribution to include the default route to advertise to neighbors.

 

HTH

 

Rick

Joseph W. Doherty Thu, 09/11/2014 - 05:24
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Also depending on you setup with your ISP, you might not need BGP at all.  Sometimes the ISP will advertize your public IP space (i.e. you don't need to), and if they do, all you need is a default route out.

PS:

Also BTW, often for basic ISP connectivity, even when BGP peering with your ISP, the ISP will not send you any routes but a default (because with a single link, there's no need for them).

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