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Design question

Level 1
Level 1

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.






1 Reply 1


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

If you learn only 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.

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