Typical Collapsed Core Design

Typical Collapsed Core Design

A typical Collapsed Core (Layer 2 Access) LAN is shown below as an example.

Here two core switches are used. Each Core does not typically require dual Supervisors unless high availability is of utmost importance. Each edge switch is connected to each Core switch by an individual trunks or EtherChannel.

The Core switches are connected via an EtherChannel. This design can act as a Distribution Block for a larger design with a separate Core where the scale or layout (e.g. separate buildings) dictates a 3 tier design, with a separate Core, is used.

Loops have been introduced for resilience.

To minimise the chance of an STP issues the following are configured:-

Core switches are configured for STP Root and HSRP (Odd and Even VLANs on alternate switches). Core switches perform inter-VLAN routing. Trunks are pruned of unnecessary VLANS.

RootGuard is configured on the downlinks from Core switches. LoopGuard is configured on uplinks and inter-Core links. Switchport Host and BPDU Guard is configured on the Edge (end user) Ports