Adv Same Public /24 from two location as active/standby using BGP.

[Cool47]

Hello,

I am looking to advertise same public

/24

from two locations with BGP setup.

SiteA connects to SiteB using MPLS by ISPX

SiteA BGP adv Public IP say 192.168.1.0/24 to ISPA
SiteB BGP adv Public IP say 192.168.2.0/24 to ISPA

Can we advertise the public subnet say

192.168.100.0/24

via SiteA as Primary? (Inbound and outbound)

Can we advertise the public subnet say

192.168.100.0/24

via SiteB as Backup? (Active only when SiteA no longer exists)

Is it possible? if so how do I setup the BGP? Can someone shed some light on this please?

Thank you.

[MHM Cisco World]

You can advertise both but for backup path use as-prepend.

That it what you need 

[Cool47]

Thank you MHM for the response. Could you pls share more on how the config looks like?

[MHM Cisco World · Accepted solution]

https://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/13762-40.html

[Cool47]

Thank you for the info. Yes I do see how it can be set it up now. The existing link 'SiteA connects to SiteB using MPLS by ISPX' which is not near to the edge device, So I can't make use of it for iBGP peering between SiteA and SiteB. 

[MHM Cisco World]

You need ibgp between siteA and siteB for outbound not for inbound.

[Cool47]

Thank you for the insight.

[Joseph W. Doherty]

BTW, you do realize

192.168.x.x is private address

space and should not be advertised to the Internet?

Assuming, though, you have a public

/24

that you can legitimately advertise to two different ISP connections, possibly BGP Conditional Advertisement, if supported on your platform, is ideally what you want to use.

[Cool47]

Thank you for the input. Yes, we have

/24 ISP

assigned IP subnet.