[c-nsp] BGP Route Reflectors

[Arnold Nipper]

On 11.07.2006 11:49 Alex Foster wrote

> I am in the process of changing our current BGP architecture from single
> site to dual site with some additional upstream peers.  Currently our
> architecture is fairly simple and common:
> 
> 	ISP 'A'			ISP 'B'
> 	   |			    |
> 	   |			    |
> 	   |			    |
> 	Router- A  -----iBGP------- Router B
> 
> Were now looking to change it to this:
> 
> 
> ISP 'A'			ISP 'B'
> Site A			 Site A
> 	   |			    |
> 	   |			    |	
> 	   |			    |
> 	Router A  -----iBGP------- Router B
>                |			    |
>  	   |			    |
> 	 iBGP			  iBGP	
> 	   |			    |
> 	   |			    |
> 	Router C  ------iBGP------ Router D
> 	   |			    |
> 	   |			    |	
> 	   |			    |
> 	ISP 'C'			ISP 'D'
> 	Site B			Site B
> 
> Im aware that the four core routers are not fully meshed - and that I
> need to implement some route reflection.  My understanding of this is
> grainy at best so here is my stab at what I think needs to be done:
> 
> Router C and Router B are RR in the same cluster with router A and D as
> clients.
> Router A and Router D are RR in the same cluster with router B and C as
> clients.
> 
> Would this provide me with the correct RR resilience whilst avoiding any
> potential routing loops ??  Is this the best way to implement this or is
> there a better way ??
> 

I would run full mesh. RR with only 4 routers does not buy you much.
Regarding # of ISP I would suggest to cut this down to two or at most
three. From my experience more than two upstreams do not really buy you
something but headaches ...


-- 
Arnold Nipper, AN45