BGP question

Unanswered Question
Apr 23rd, 2009

Our company is moving some servers, firewalls, routers etc from Data center A to Data Center B (located in the same city).

There is only a small amount of gear involved although the move will be done in two stages, over a weekend to break it down into manageable chunks.

At the end of the task we will have no equipment left at Data Center A.

Connections to both Data Centers is via a fiber network that also connects to a remote Data Center and also to several branch offices.

A BGP routing process is used to advertise the networks between sites. Data Center A & Data Center B are different AS numbers.

To avoid re-addressing hosts and default gateways etc I would like to use the existing Data Center A "Interconnect Network" eg 10.10.36.0/26 at Data Center B. So for a short time it would need to exist at both locations.

The network is basically router --> layer 2 switches --> multiple firewalls with a leg on the Interconnect --> Firewall LAN segments.

Static routes on the router point to the next hop firewall and some static routes on the firewalls point directly to other firewalls as the next hop where necessary with the default route pointing to the router.

Is it possible to advertise the 10.10.36.0/26 network at both sites (Data Center A & Data Center B).

Can I filter the routes I need to advertise down to host routes?

I need to be able to connect remotely from Data Center C to the remaining gear at Data Center A and also be able to connect to the gear at Data Center B that will move in Stage I

Would I do this with a distribute list?

I do not want to filter any other network routes as I will remove those networks from the BGP process and re-advertise them from the new site router at the appropriate time.

Any comments, help etc would be much appreciated.

Thanks Peter.

I have this problem too.
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Giuseppe Larosa Fri, 04/24/2009 - 01:25

Hello Peter,

I would use a different approach:

during migration use NAT on the new datacenter to make hosts of 10.10.36.0/26 appear as something else

Advertise that different subnet in BGP.

remaining hosts in site A will be reached via 10.10.36.0/26 subnet.

new hosts will be reached via new subnet.

At the end of the process you can remove the NAT statements and start to advertise 10.10.36.0/26 on the new site

Hope to help

Giuseppe

pschwalger Wed, 04/29/2009 - 16:25

Giuseppe,

Thank you for your response...much appreciated.

I think you are right and NAT or creating a new network at the new Data Center are probably the way to go.

NAT is probably achievable and is only required for a brief period until all the gear has been moved.

regards Peter

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