Cisco Data Center Architecture

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As the CCIE Data Center track has been announced a lot of people started to study for this including me :-) With all CCIE tracks the first exam that needs to be passed is the Written exam. For the Written Exam there is a separate blueprint, with a lot of topics... I am going to go trough and explain all of the blueprint topics in several blog posts and make sure everything is discussed. The first topic where the written blueprint starts with is "Describe the Cisco Data Center Architecture" and that is where this blog post will be about :-)

Here we go ...

The building blocks of an enterprise network are typically:

  • Campus network (desktop network, wireless access points, IP Phones, Desktops etc. etc)
  • Private WAN (Private company WAN Network, MPLS, Frame Relay, etc. etc.)
  • Remote access (Remote VPN access, ASA etc. etc.)
  • Internet server farm (Internet facing servers that can be accessed from the internet, internet facing applications)
  • Extranet server farm (Environment for customers)
  • Intranet server farm (Internal servers that can be accessed internally, internal tools or applications)

Data Centers typically house many components in order to support the infrastructure building blocks. We are talking about devices like the core switches that are part of the campus network, or the edge routers of the private WAN and so on...

Data Center designs can include any or all of the different building blocks listed above, including any or all server farm types.

Each type of server farm can be a separate physical entity, depending on the business requirements of the enterprise.

For example, a company might build a single Data Center and share all resources, such as servers, firewalls, routers, switches, and so on and another company might require that the three server farms be physically separated with no shared equipment.

The enterprise Data Center architecture is consists of many functional areas.

There is also an architecture of a generic enterprise Data Center that is connected to the Internet and supporting an intranet server farm, a very straight forward architecture.

Other types of server farms follow the same architecture used for intranet server farms but with different scalability, security, and management requirements.

The picture below shows the topology of the Data Center architecture. The "Internet Edge" is not included but it speaks for itself that we need this as well preferably dual ISP links. Note that this topology can be duplicated and have an DCI (Data Center Inter-Connectivity) which is nothing more then a Dark Fiber (in a ring) between these two data centers for redundancy purposes (business continuance / availability)


The server farm typically has the following layers:

Aggregation layer (The aggregation layer is the aggregation point for devices that provide services to all server farms)

Access layer (The access layer provides Layer 2 connectivity and Layer 2 features to the server farm)

— Front-end segment (The front-end segment consists of Layer 2 switches, security devices or features, and the front-end server farms)

— Application segment (The application segment has the same network infrastructure components as the front-end segment and the application servers)

— Back-end segment (The back-end segment is the same as the previous two segments except that it supports the connectivity to database servers)

Storage layer (The storage layer consists of the storage infrastructure such as Fibre Channel switches and routers that support small computer system interface (SCSI) over IP (iSCSI) or Fibre Channel over IP (FCIP))

Data Center transport layer (The Data Center transport layer includes the transport technologies required for communication between distributed Data Centers, distributed server farms for the purposes of remote mirroring, replication, or clustering)

Some of these layers might be optional in the Data Center architecture but they represent the trend in continuing to build highly available and scalable enterprise Data Centers.

To summarize, Data Centers are just strategic components of an enterprise that house the critical parts of the business:

  • Applications
  • Data
  • Computing infrastructure

The Data Center network can be seen as the heart of the complete enterprise network and is vital to sustaining the normal operations of the business. If your heart stops you have a problem and if your Data Center stops (application unavailability, data unavailability etc. etc. ) you have a problem as well... However a Data Center outage could lead to heart problems ;-) anyway what I am trying say is that the Data Center network architecture is driven by business requirements, and if the business is not running money is lost, which could lead to the fall of the company, which lead to the loss of your job ;-)

The criteria that SHOULD guide the design of a Data Center are:

  • Availability (you want to have as minimal outages as possible)
  • Scalability (you want to add capacity easily without too much changes, because changes cost time and money)
  • Security (you don't want internal/external hackers infiltrating your network environment)
  • Performance (you want your hosted applications to be fast)
  • Manageability (with complex data centers, the management of it become complex as well, we need to avoid too much complexity if this is not necessary)

The Data Center designs that you create should all be based on these principles.

The distinct services that are usually offered by the Data Center network are:

  • IP infrastructure connectivity (the IP network as in routing and switching)
  • SAN infrastructure connectivity (the Storage Network as in Fibre Channel fabric switching)
  • Application optimizations (performance as in load balancing, caching, and SSL offloading)
  • Security (as in the use of ACLs, firewalls, IDSs, and secure management)
  • Business continuance (availability as in site selection (IP based or DNS based), SAN extension, and Data Center Inter-Connectivity)

Hope this helped with understanding the first topic of the CCIE Data Center blueprint and my next blog topic will be "Describe the products used in the Cisco Data Center Architecture"

If you like my blog posts, please let me know below (in a comment) or trough twitter!

Bye for now ...