Data Center NETWORKS (what do they look like??) // FREE CCNA // EP 7

About this video

In this free CCNA episode, the creator explains how data center networks are designed and why they differ from campus networks. A company can run its own small data center, rent rack space in a larger facility with redundant power and cooling, use cloud providers such as AWS, Google Cloud or Microsoft Azure (which still run on someone else’s data center), or combine these in a hybrid approach. The traditional design is three-tier: top-of-rack access switches in each rack connect to distribution/aggregation switches, which connect to large core switches. That model was built for north-south traffic to and from the internet, but virtualization made server-to-server east-west traffic dominant — the creator says roughly 70 to 80 percent of data center traffic — and the three-tier path adds too many hops while spanning tree blocks redundant links. The modern answer is spine-leaf (also called Clos): leaf switches replace top-of-rack switches and every leaf connects to every spine switch, spines and leaves do not connect to their own kind, and any server reaches any other in a predictable maximum of two hops with load balancing across Layer 3 leaf-to-spine links. He notes Cisco Nexus switches are the data-center line, versus Catalyst for campus, and that spine-leaf is the underlay beneath overlay systems such as Cisco ACI.

Key takeaways

• Data center options include building your own, renting racks in a colocation facility, using cloud providers, or a hybrid mix of all three
• Traditional three-tier design uses top-of-rack access, distribution and core layers and was optimized for north-south (internet-facing) traffic
• East-west server-to-server traffic, driven by virtualization, is now the majority, making three-tier hops and spanning-tree-blocked links a problem
• Spine-leaf fixes this: every leaf connects to every spine, no leaf-to-leaf or spine-to-spine links, and server-to-server communication is at most two hops
• Leaf-to-spine links are typically Layer 3, allowing all links to stay active and load-balance instead of being blocked by spanning tree

Episode details: published October 11, 2020 · 20:17 long. Summary written by Self Growth Videos from the episode itself. Business results and any income figures mentioned are NetworkChuck’s own claims, shared for education — they are not typical or guaranteed.

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