bgp Advertising for the Same IP from Two location for the Same Provider that have tow AS number

[Garbosh]

we have migration plan on going for your datacenter location our company used to be ISP and we've got to block of subnet x.x.0.0/19 and x.x.224.0/19 we used to advertise this to block to our service provider from the BGP with network statement network x.x.0.0/19 and x.x.224.0/19 with no filtration, the problem is our previous engineers used to use IP address from this blocks as point to point in our internal BGP and links between our PE and cores /30 instead of using private IP and also using loobpack from this block /32,,no there will be another internet connectivity from the new datacenter with different AS number from the same provider and we need to advertise this blocks again in the new datacenter using AS-prepending method to prefer the old connection until we shutdown the old data center , i am afraid that AS-prepending will not work properly and the problem is we cannot sue more specific subnet due to time issue can we do any kind of BGP manipulation to always prefer the advertise from the old Data center until we shutdown it

[Giuseppe Larosa]

Hello Garbosh,

your own AS number prepending will work implement it on new DC toward the second ISP AS number for the two /19 prefixes.

Note: how the public IP addresses blocks are used inside your network is not so important for the eBGP route manipulation.

make possible to communicate between the two locations using a dynamic protocol like OSPF over an indipendent L2 connection.

Can you clarify who is going to use a second different BGP AS number ?

the ISP or you in the new location ?

Because your post is not so clear about this.

Depending on who is going to use a different AS number the use of AS path prepending can be a good solution or not.

My understanding is that it is the ISP that will use a different AS number to peer in eBGP with you in the new location/ DC

Hope to help

Giuseppe

[Garbosh]

I do appreciate your effort to answer me

and to clarify some point, we used to be a small ISP company but we are in
phase of shutdown the ISP business and move our internet customer to new
ISP using our own IPs (1.1.0.0/19) , we used to use block of 1.1.0.0/19
(this IP is for example only ) for the internet customers and 2.2.224.0/19
(also for example) for hosting clients (website , VM. etc)
and the way we advertise the bgp to our old IGW ( our internet gateway)
is 1.1.0.0/20 and then 1.1.16.0/20 (we just divided the subnet) also the
same for the 2.2.224.0/20 and 2.2.240.0/20

for the new location we don't actually want to use the old location any
more but the old location is up and running until all the internet clients
migrate , there for the new location we think if we can used as backup of
the internet for the 2.2.0.0/20 and we have three server only in the block
of 1.1.0.0/24