[c-nsp] BGP Route Reflectors

[Alex Foster]

It will not be possible for me to implement a full mesh (at the physical
level), due to restrictions on ports/connectivity between sites - hence
my desire to run partial-mesh with route-reflectors.  The # of ISPs is
really to allow us to maintain complete diversity across both sites - so
that if we loose site A all traffic would use the alternative links
through site B (and still have upstream resilience).  The nature of
traffic is VOIP so high-availability is important to us in all
scenarios.  

Now that you understand my network options - I have had feedback from
another list member who has advised me to steer clear of clustering and
to configure each router as a RR with the corresponding iBGP peers as
clients:

Router A is RR to clients B and C
Router B is RR to clients D and A
Router C is RR to clients A and D
Router D is RR to clients B and C

This would seem to make sense to me - but then Im no expert - so if you
have any additional ideas or feedback, feel free to comment.

Regards

Alex



-----Original Message-----
From: Arnold Nipper [mailto:arnold at nipper.de] 
Sent: 11 July 2006 11:43
To: Alex Foster
Cc: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] BGP Route Reflectors

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


This message has been scanned for viruses by MailController -
www.MailController.altohiway.com


The information in this e-mail and any attachments is confidential and may be subject to legal professional privilege. It is intended solely for the attention and use of the named addressee(s). If you are not the intended recipient, or person responsible for delivering this information to the intended recipient, please notify the sender immediately. Unless you are the intended recipient or his/her representative you are prohibited from, and therefore must not, read, copy, distribute, use or retain this message or any part of it. The views expressed in this e-mail may not represent those of Gamma Telecom.

This message has been scanned for viruses by MailController