Designing Cisco Network Service Architectures - Free Books

NoteThis frame relay design approach gives us 5 areas per ABR (128/32 = 4, plus area 0). Thiswas very aggressive design as of 5-10 years ago, when 3 areas on one router wasconsidered aggressive. One alternative would have been to put 64 hotels per area. Thisalternative would however waste more bandwidth on LSA flooding within each area. Forpurposes of this Case Study, we will stick with the aggressive OSPF design is used.Call Center ModuleThe Call Center routers speak EBGP to the MPLS VPN provider, also to the core routers. EachCall Center runs EIGRP, but that is not visible from the Data Center.Call Center ModuleEBGPMPLSVPNPartner ModuleThe Partner Module uses static routing internally, whatever the external routing may be. Thecore-facing routers use BGP network statements to pass a summary of these routes into thecore. Default routing cannot be used to reach partners, since that needs to direct traffic to thecorporate Internet links via the Corporate Internet Module.Partner ModuleStatic routingPartnersHQ ModuleThe HQ Module uses OSPF to the four HQ buildings. Each HQ building WAN routersummarizes the building into the WAN, which is area 0 for the HQ OSPF autonomous system.One VLAN per area uses the DWDM connection to tie each ABR in data center A to its “twin”in Data Center B. Each pair of aggregation routers in each data center connect via a VLAN tothe corresponding pair in the other data center via two VLANs that are in their area 0, to makeHQ ModuleHQ 1 & 2the area 0 networks contiguous.OSPFHQ 3 & 416 Designing Cisco Network Service Architectures (ARCH) v2.0 © 2007 Cisco Systems, Inc.