[c-nsp] Multihomed network -> iBGP questions

[Thierry]

Dear,

 

I am currently building a network and I would like to confirm my design. 

 

Two routers (A and B) will be connected to a different IP transit provider.
These providers will advertise to us the full Internet table. 

 

As internal routing protocols, I would like to use iBGP for all customers'
routes and OSPF for all backbone routes (loopbacks and PtP between the
routers).   

 

I would like to have the full internet table only on the two routers
connected to the providers (A and B). All the others (C to J) will only have
the internal routes + a default route coming from the two border routers (A
and B) using OSPF. 

 

I would like also that all outgoing traffic goes to the same router (for
example A) and this router will choose to send the traffic to the provider
connected to himself or to send the traffic to router B (in case it has a
better route), which will send to his provider. 

 

I would like also that the network is scalable, for example if we have in
the future a new customer connected to the router F and would like a full
internet table. In this case, we must advertise the full table to router F,
which can advertise to the customer.  

 

My idea was:

 

-          OSPF for backbone routes.

-          iBGP for customer routes.

-          eBGP with the providers.

-          iBGP between A and B with no restrictions. 

-          Full mesh iBGP between all the routers (except between router A
and B) with a filter-list applied out -> ip as-path seq 1 permit ^$ this
should only advertise prefixes originated inside the AS and where a network
statement is configured into BGP.

-          Default originate on router A and B inside OSFP configuration
with a different metric. Ex: A= "default-information originate metric 1
metric-type 1" and B= "default-information originate metric 100 metric-type
1".  

-          For the example explained above, we change on router A and B the
configuration with router F -> move to the iBGP with no restrictions. 

 

What do you think about my design? Do you have any suggestions or comments? 

 

Thanks. 

 

Thierry