08-28-2019 09:30 PM
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
09-01-2019 05:18 AM
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
09-02-2019 09:23 PM
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