First steps: designing the network

There are some questions, we need ask ourselves before beginning to build a Data Center. ¿What's the data center for? ¿Which architecture should I choose? ¿ TOR, EOR, MOR ? ¿ Racks or blades?¿How to avoid data loss? .... and much more.

In this post we are trying to solve some questions referred to the network of our DC, but as you can imagine a single post isn't enough to solve all that questions, so we will continue solving it in future posts.

Architecture design:

Based on the three main architectures design, TOR (Top of the rack), MOR(Middle of the row), EOR (End of the row), we will choose:

• For the access layer a TOR architecture ( with 2 rack switches at top of the rack)
• For the aggregation layer a EOR architecture ( with 2 blades to ensure the connectivity)

With this configuration we will try to minimize the complexity of the cabling and achieved a modular deployment, though the amount of switches needed will be high.

If you want to know more about these architectures you can find more information here.

Avoid data loss:

Traditionally data centers were separated into LAN areas over ethernet connections and SAN areas through Fiber Channel connections.

In a 3rd generation data center we try to have a consolidated network, which means we have to choose between ethernet and fiber channel.The problem was that in one hand ethernet is an affordable technology but it has a lack of reliability ( loss of packets), and in the other hand Fiber Chanel don't lose packets but is an expensive technology.

The solution is Fiber Channel over Ethernet (FCoE), that combines the reliability of Fiber Channel protocol with the reduced cost of the ethernet connections. To do so, we will have to implement the following protocols:

• Data Center Bridging eXchange (DCBX)
• Priority-based Flow Control (PFC) - IEEE 802.1Qbb
• Enhanced Transmission Selection (ETS) - IEEE 802.1Qaz 811.1Qbb

You can find more information in this HP paper.

According to all these specifications, we have chosen the following HP devices:

• EOR : HP StoreFabric SN8000B
• TOR switches: HP Store Fabric SN40o0B