Common Terminology

• Start → Devices connected to a central device

• Full Mesh → All devices connected to each other

• Partial Mesh → Some devices are connected to all devices, but some are connected to only a few

2-Tier Campus LAN Design (Collapsed-Core Design)

In this design there is two layers of switches:

• Access Layer: It is the layer that end devices connect to
  • Lots of ports
  • QoS marking is done here (the soon the better)
  • Layer 2 Security techniques are done here
  • PoE is present here

• Distribution Layer (Aggregation Layer): It is the layer that AGGREGATES the Access Layer Switches
  • Border between Layer 2 and Layer 3
  • Will connect to the WAN Routers
  • There is usually FHRP between their SVIs
  • Are connected to each other via Layer 3, even other Distribution Layer Switches (Full Mesh part)

3-Tier Campus LAN Design (Core Design)

This design has three layers:

• Core Layer: aggregates (connects) the Distribution Layer Switches
  • ALL connections are Layer 3
  • CPU-intensive tasks such as QoS, Security and etc., should be avoided
  • ‘Fast transport’ → Rapid forwarding decisions
  • Redundancy

• Distribution Layer

• Access Layer

Spine-Leaf (Clos Architecture)

This is the modern design of Data Centers. Tradition 3-Tier designs work well for North-South traffic. However, for West-East traffic, the most intense traffic in a Data Center, the 3-tier architecture is not ideal. This is due to the vast amount of VMs talking to each other and shared resources.

There are two types of switches:

• Spine switches: Connects to every Leaf

• Leaf switchers: Connects to every Spine
  • Similar to the access layer switches, these switches are where the end devices connect to.

Path is randomly chosen to load-balance the workload. Also, with this architecture, the connection between servers that are not in the same switch are always the same quantity of “hops” away from each other.

SOHO Networks

SOHO (Small Office/Home Office) networks are usually smaller environments like small offices or homes. These networks are not as complex as entreprise-level environments.

SOHO devices usually perform more than one function like: