Design question

[pronin_sergey]

Hello guys,

our company has the following design.

• Three datacenters in different countries.
• In each DC there is a core. It is usually stacked 3750X switches.
• OSPF runs on the cores to exchange internal routes
• Two borders in each DC. It might be Cisco, Juniper or even Linux. Borders run multimode BGP with various providers. 
• Each DC announces its own /24 network.
• There is a full mesh iBGP between borders on virtual interfaces, that are built over internal OSPF.

Question is:

Is it a good design or not?

1) I would like to move iBGP to cores and configure route reflectors on them. Is it a good idea?

2) We have a public prefix /21. Instead of announcing /24 in each DC I would like to announce /21 in all DCs + /24 in each. But I don't know what to do with the firewalls in each DC. They are stateful.

--

Regards,

Sergey

[Vasilii Mikhailovskii]

Hello.

If run full-table BGP, I would say it might be a bad idea to run BGP inside your network.

If you learn only 0.0.0.0/0 via BGP, then it's easier to redistribute it into IGP per DC.

Regarding public prefixes - /21 vs specific /24s might be a good idea; if you have DMZ, then the challenge is to route traffic to proper DMZ (you may try it with different VRF).

PS: it's hard to say if it's good design or not, we need to know what are the original business requirements and where different services will be located.