Route Summarization from Distribution to Core

  Route Summarization from Distribution to the Core This post is about a particular problem being faced once route summarization is introduced and how it can be avoided. This concept is covered very well in these books from Cisco Press: http://www.ciscopress.com/store/ccde-study-guide-9781587143809 http://www.ciscopress.com/store/optimal-routing-design-9781587051876 In this topology diagram 1 above, C1 and C2 are the core routers. … Continue reading Route Summarization from Distribution to Core

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Always avoid Single Point of Failures SPOFs

I was told recently that organization XYZ suffered outage because one of their core devices did not have redundancy. In other words, there was a single point of failure somewhere in their network. And then their technical team kept fire fighting until the issue was resolved. This post is about avoiding this nuisance called SPOF … Continue reading Always avoid Single Point of Failures SPOFs

OSPF Area Border Connection Behavior

OSPF Area Border Connection Behavior Reference: Designing Cisco Network Service Architectures ARCH Foundation Learning Guide - Cisco Press In the case of OSPF, area definition is on a per layer 3 interface basis. For example, referencing the topology above, the link between router D and router F is placed in area 1 Traffic crossing the … Continue reading OSPF Area Border Connection Behavior