Hi Gaurav, I have read through that doc, and it addresses EIGRP SoO only. My questions are specifically about BGP SoO.
Keller Giacomarro kelle...@gmail.com On Mon, Oct 8, 2012 at 1:48 AM, Gaurav Thukral <pearlgau...@gmail.com>wrote: > Hi > > Kindly go through the below doc. > > > http://blog.ine.com/wp-content/uploads/2010/04/understanding-eigrp-soo-bgp-cost-community.pdf > > Thanks > Gaurav > > On Mon, Oct 8, 2012 at 9:48 AM, Keller Giacomarro <kelle...@gmail.com>wrote: > >> I am having issues understanding when to use SoO where. These are the >> scenarios I can think of where we'd be using BGP as the IGP and would >> consider the use of some of these more advanced BGP multi-homing >> features... >> >> Two sites, different ASNs, no backdoor link >> - no special config needed >> >> Two sites, same ASN, no backdoor link >> - use either allowas-in or as-override to allow the sites to accept routes >> from each other >> - if any of the site are multi-homed, use SoO to keep the routes from >> circling back into the same site via the other PE >> >> Two sites, different ASNs, with backdoor (backup-only) link >> - peer the backdoor CE routers via eBGP and prepend to prefer the MPLS >> link >> >> Two sites, same ASN, with backdoor (backup-only) link >> - ??? >> >> One site, one ASN, multiple MPLS exit points, with intra-site active >> (non-backup) links >> - no special config needed, but MPLS cannot be used if the internal site >> becomes segmented (due to AS_PATH loop prevention) >> >> First, are the above designs correct? >> >> And second, what is the proper way to setup "Two sites, same ASN, with >> backdoor (backup-only) link"? I put it into GNS3, and I can't get the >> traffic to prefer the MPLS backbone instead of the backup (iBGP) link. >> The >> PE routers both prefer the eBGP link towards the internal network, and >> neither will accept the (preferred) iBGP ad from their peer PE router. It >> works fine going the reverse -- backup link works great, and if the backup >> link goes down the MPLS core is used. >> >> The only way I can figure to get the desired "MPLS primary, backdoor link >> is backup" behavior is to do some kludge between the CE routers so that >> they only advertise the routes to each other if the MPLS network is down. >> >> Is the only time you want to use BGP SoO when all your sites are on the >> same AS (forcing allowas-in or as-override), and some are multihomed? >> Otherwise, won't BGP AS_PATH loop prevention prevent the looping? >> >> Very confused, appreciate your input! >> >> Keller Giacomarro >> kelle...@gmail.com >> >> >> Blogs and organic groups at http://www.ccie.net >> >> _______________________________________________________________________ >> Subscription information may be found at: >> http://www.groupstudy.com/list/CCIELab.html >> >> >> >> >> >> >> >> > > > -- > Thanks & Regards, > Gaurav Thukral > > > > > > > _______________________________________________ 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
