Sample Reference Topology¶
For a consistent frame of reference, a sample reference topology has been deployed, provisioned and used throughout the book. This ensures a consistent reference for the different scenarios and troubleshooting exercises.
This section explores the different aspects of the reference topology, from the logical application view to the physical fabric and any supporting details that will be used throughout the troubleshooting exercises. Each individual section will call out the specific components that have been focused on so the reader does not have to refer back to this section in every exercise.
The topology includes a Cisco ACI Fabric composed of three clustered Cisco APIC Controllers, two Nexus 9500 spine switches, and three Nexus 9300 leaf switches. The APICs and Nexus 9000 switches are running the current release on www.cisco.com at the initial version of this book. This is APIC version 1.0(1k) and Nexus ACI-mode version 11.0(1d).
The fabric is connected to both external Layer 2 and Layer 3 networks. For the external Layer 2 network, the connection used a pair of interfaces aggregated into a port channel connecting to a pair of Cisco Nexus 7000 switches that are configured as a Virtual Port Channel. The connection to the external Layer 3 network is individual links on each leaf to each Nexus 7000.
Each leaf also contains a set of connections to host devices. Host devices include a directly connected Cisco UCS C-Series rack server and a UCS B-Series Blade Chassis connected via a pair of fabric interconnects. All servers are running virtualization hypervisors. The blade servers are virtualized using VMware ESX, with some of the hosts as part of a VMware Distributed Virtual Switch, and some others as virtual leafs part of the Cisco ACI Application Virtual Switch. The guest virtual machines on the hosts are a combination of traditional operating systems and virtual network appliances such as virtual Firewalls and Load Balancers.
To maintain a consistent reference throughout the book, an Application Profile (AP) was built for a common 3-tier application that was used for every troubleshooting sample. This AP represents the logical model of the configuration that was deployed to the fabric infrastructure. The AP includes all the information required for application connectivity and policy (QoS, security, SLAs, Layer 4-7 services, logging, etc.).
This particular AP is a logical model built on a common application found in data centers, which includes a front-end web tier, a middleware application tier, and a back-end database tier. As the diagram illustrates, the flow of traffic would be left to right, with client connections coming in to the web tier, which communicates with the app tier, which then communicates to the database tier, and returns right to left in reverse fashion.