BGP Route Learning on Dual Router - Dual ISP

[netbeginner]

Hi All, 

Please help to get solution for below query :

We have our own Public IP pool of /24 subnet and ASN.  02 Routers connected with 02 Different Internet Service Providers and both the routers are connnected with iBGP also at LAN side. Eg :

Router-1  ---> Connected with ISP-1   (running eBGP)

Router-2 ----> Connected with ISP-2   (running eBGP)

Requirement : Routes learned from ISP-1 on Router-1 should not be learned via ISP-2 via Router-2

Rgds

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[Flavio Miranda]

Hi @netbeginner 

 You may not prevent R2 from learn the routes but you can  work with local preference and make ISP-1 the preferred path by assigning higher preference.

[MHM Cisco World]

Should not or prefer prefix ?
this can help us in solve issue 

[sidshas03]

1. Access the configuration settings of Router-2, where you can modify the BGP settings.

2. Create an access list on Router-2 to match the routes learned from ISP-1 that you want to filter. This access list should specify the specific routes you want to prevent from being learned via ISP-2.

3. Define a route map on Router-2 that references the access list created in the previous step. The route map will be used to match the routes and apply a specific action.

4. Within the route map, set the action for the matched routes to "deny." This action ensures that the routes will not be accepted or advertised to other BGP peers.

5. Apply the route map to the BGP configuration on Router-2, specifically for the BGP neighbor session with Router-1. By doing this, the filtering will only affect routes learned from ISP-1.

6. Save the configuration changes on Router-2.

[Joseph W. Doherty]

As both @Flavio Miranda and @MHM Cisco World likely have in mind, the usual approach would be to prefer ISP-1 learned routes.

An advantage of what you propose would be saving RAM, on both your routers, as routes known via ISP-1, I believe, would be excluded from ISP-2.  However, if so, consider what happens if connectivity to ISP-1 drops.  You need to wait for ISP-2 routes to load (unless, perhaps, you have a static default route pointing to ISP-2).

[M02@rt37]

Hello @netbeginner,

please more elaborate :Requirement : "Routes learned from ISP-1 on Router-1 should not be learned via ISP-2 via Router-2"