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Showing posts from November 8, 2019

Cisco SDA - Components

Cisco Software Defined Access is a new paradigm towards building Enterprise Networks. Primarily built upon the Cisco's DNA Center software, it leverages several next-generation components to design, provision and apply policy to create an intelligent wired and wireless network infrastructure. Cisco DNA Assurance which turns the network devices into sensors, giving visibility to everything on the network; guided remediation which automates resolution to keep the network at its optimal performance and thereby improve the end user experience, are some of Cisco's USPs. Cisco SDA accomplishes this intent based networking via the following components: Fabric Control Plane nodes: Based on LISP map-server and map-resolver functionality combined together on the same node, control plane node (database) tracks the endpoints in the fabric site and associates the endpoints to fabric nodes. Border nodes and edge nodes register with the control plane nodes. Control Plane node can be dedicate

Cisco ACI - Forwarding inside the Fabric

One of the most intriguing (of course, if you get the hang of it) or depressing concepts of Cisco ACI is how the traffic forwarding takes place inside Cisco ACI. Let's start with an endpoint sending the frame to the connected leaf: The leaf checks the destination MAC address of the frame. The leaf will do a layer 2 lookup to find the destination MAC. If the leaf knows the location of the destination MAC (either local to the leaf or some other leaf), it will determine the destination's EPG. Depending on the EPG, it would determine if a contract is required to allow the frame to forward.. If yes, it would look into the L3 and L4 contents of the packet to determine if the contract exists. If it does, allow the traffic, if not drop. If the frame has the destination MAC address of that of the leaf, it will be routed. This will be the standard destination IP based routing. If a route exists for the destination in the VRF of the source, it is routed. If not, it will be dropped. With r