Cisco IOS - A Look into BGP Peer Groups

What is a BGP Peer Group? BGP peer groups are used to simplify configuration and to improve performance. This is achieved by assigning the same outbound policy to each of the neighbours. Because UPDATEs are generated only once per peer group rather multiple times for each neighbouring router, peer groups…

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What is a BGP Path Attribute?

TL;DR A path attribute is an additional piece of information associated with a prefix, included within the UPDATE packet during route exchange. Path attribute types include: Well-known - Must be recognized by all BGP implementation Mandatory ALWAYS be included within BGP UPDATE. Discretionary MUST be recognized by ALL implementations.…

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The History of Spine and Leaf Architectures

Introduction Within this article, we will look at the history of spine and leaf. We will first look at the problems seen with traditional networks, the background to the spine and leaf architectures aka Clos, and then finally look at how this fits into the spine and leaf architectures of…

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What is PIM (Protocol Independent Multicast)?

Introduction PIM (Protocol Independent Multicast) is a multicast routing protocol, that is used to send traffic from a single source to multiple destinations across a network. PIM is a collection of three protocols - PIM Sparse Mode, PIM Dense Mode and PIM Bi-directional .  PIM is termed protocol-independent because PIM…

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What is BFD?

TL;DR BFD (Bi-Directional Forwarding Detection) is a highly efficient keepalive mechanism for routing protocols, that can detect link failures in milliseconds. Background As stated at http://brbccie.blogspot.com/, All routing protocols have some way of detecting failure, usually timer-related. Tuning the timers can theoretically get you sub-second failure…

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What is Segment Routing?

Introduction Within this article, we answer the question - What is Segment Routing (SR)? But before we do we should first review MPLS, to understand the key benefits that SR brings. Let's go... MPLS Before looking at segment routing it's good to understand traditional MPLS. With traditional MPLS, a component…

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