Robert,BGP has many features that you can tweak to achieve what you want. A simple AS-PATH access-list 'ip as-path access-list 1 permit ^$' applied in outbound direction to both the ISPs (of course on both the routers) will ensure that you only advertise what originates in your AS. This prevents your AS from becoming a transit AS. To manipulate traffic going out of your AS, you can play with Local Preference or Weight attributes (setting up local pref will affect both routers in your AS). To manipulate traffic coming inside your AS, you can tweak MED or use AS-PATH Prepend. (AS-PATH Prepend is suggested, as it is a transitive BGP Attribute). Is it a good practice to install full routing table / partial routing table or only default route? This depends on what you want to do with BGP & the purpose of using BGP in the first place. One of the reasons to install Full routing table could be that now you have the view of the entire topology (Internet) & this gives you the power to control how traffic leaves your AS on per destination basis. By the way none of the above guarantees 'Symmetric Routing'. :) Here is a link which talks about the use of PBR (Policy Based Routing) which can be used to achieve Symmetric routing. https://supportforums.cisco.com/thread/2183685 Hope this helps!!
________________________________ From: Robert Beck <[email protected]> To: [email protected] Sent: Friday, 12 April 2013 11:42 PM Subject: [OSL | CCIE_RS] BGP Best practices Hi all, I have BGP questions. But first the set up. ISP1 connectected to R1 ISP2 connected to R1 ISP2 connected to R2 IBGP between R1 and R2 redistributing 0.0.0.0 from EBGP into IGP that is received from primary ISP. Which from what I've found on google searches that seems to be the norm. Both routers are receiving the full BGP table. Several Networks advertised out both ISPs. Now the questions.. 1. Is it a good idea to receive the full BGP table other than the cool factor? Also, is there a way to prevent from becoming a transit hop while receiving the full BGP table? When you receive the full BGP table, isn't becoming a transit area automatic? 2. Is there a good way to load balance outbound traffic to the internet in this set up? 60/40? If the route goes out ISP1 and network A is advertised to ISP2 will asymetric routing work in this case? I think not. I would assume the best practice method would be to have the path go out which ever Network is advertised to which ISP. For example, if Network B is advertised out ISP2 then have them route that way instead of ISP1. thanks for any info. _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com http://onlinestudylist.com/mailman/listinfo/ccie_rs _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com http://onlinestudylist.com/mailman/listinfo/ccie_rs
