Discuss the spine and leaf architecture? Give some guidelines for configuration when implementing such an architecture?
The spine and leaf architecture describes the way in which the switches are interconnected. It is primarily a physical layer architecture. The distinguishing feature, compared to the more traditional tiered model, is that every spine switch has a physical connection to every leaf switch. There is no specialized configuration on the devices to achieve this architecture.
Now having said that, there are some guidelines for configuration to keep in mind when implementing such an architecture, but these are not specific to the architecture itself but to general networking best practices.
Don’t use STP – Ensure that your configuration does not rely on STP to prevent L2 loops, otherwise, you waste available bandwidth by causing all links but one to remain idle
Configure VLANs only on leaf switches – Spine switches should remain unaware of VLAN configurations. They should perform routing between the VLANs configured on the leaves.
Routing protocols configured to function with equal cost multipath should be implemented to ensure the most efficient usage of the multiple uplinks to the spine switches. “
Finally, there are two popular data center physical designs “Top of Rack”, and “End of Row” that you also be aware.
Top of rack (ToR) which is also known as In-Rack design. In this approach, the network access switch is placed on the top of the server rack; hence, servers are directly connected to the network access switch. This means that 1 or 2 Ethernet switches are directly installed inside the rack, therefore copper cables stay inside the rack. It is cost-effective because it reduces the number of copper cables between racks.
In End of Row (EoR) network design, there is a direct connection of each server in the rack with the end of row aggregation switch. This eliminates the need to connect servers directly with the in-rack switch.
In ToR each rack is an independent unit whereas in EoR the whole row of servers acts as a group within the data center.
