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Routing

BGP table analysis and statistics

For those of you who are interested in obtaining some useful information about the BGP table (Internet routing table), check out the following websites for some useful reports, analysis and statistics. Nice resources for daily work, research and planning. Play around: BGP Routing Table Analysis Reports. Check bgp4.as also forĀ  a ton of tools and information about the BGP table.

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CEF and load sharing

Load-sharing is one of the clumsy areas that is full of confusing parts. In this post we should be covering its ABCs, and latter on we should be covering more parts in details. We chose the name “CEF and load sharing” as the post name due to the main role that CEF plays when talking about load sharing. In IP routing context the forwarding/switching mechanism that the router uses is the actual controller of the load sharing process (data/forwarding plane operation), having multiple routes in the routing table has no significance on how exactly will load sharing be done, you …

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BGP Next-hop address tracking

In this post we are going slightly deep into BGP operation on the CISCO IOS. Lets start this by discussing the BGP scanner operation, then we can talk about the next-hop address tracking feature. For each route installed in the BGP table a next hop address must exist and this next hop must be reachable in terms of an IGP. If the next hop is not reachable the route will not be considered for the best path algorithm and will never be used by BGP.

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Why BGP?

This question is mostly repeated by newbies when they start learning about BGP and sometimes it is left unanswered clearly. In the simple dialogue below I will try to explain when BGP is mostly used and why? Can we connect two or more networks by an IGP? The answer is yes from the technical point of view, you can use an IGP to connect one or more networks and exchange routing information between them. From the design point of view the answer is may be or it depends on the specific case, however generally speaking this is not a best …

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IS-IS and fast convergence ongoing tricks

Been a while since my last post, I was extremely busy doing a lot of things, anyway I am glade to be back. This post I am going to cover a nice tool for enhancing IS-IS convergence, I am really amazed by the ideas that the guys out there pop up. Inventing such wonderful tools requires intellectual open minds (it’s not relatively a new feature), enough talking and lets get to the point.

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OSPF & IS-IS Router ID

When you think about Router ID in any link state protocolĀ  two requirements come to mind: Each router must be identified by a Router ID and an Area to exist in. This Router ID must be unique inside a single IGP domain. IS-IS refers to the this ID as a System ID (SysID) and OSPF refers to this ID as a Router ID (RID). There are some best practices that can be used to ensure the uniqueness of the router ID within the IGP domain. In a previous post Mohammed discussed the OSPF RID, so I will focus on the …

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