Information Technology Reference
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Campus Layer Design Best Practices
Campus Layer
Best Practices
Access layer
Limit VLANs to a single closet when possible to provide the most
deterministic and highly available topology.
Use RPVST+ if STP is required. It provides the best convergence.
Set trunks to ON and ON with no-negotiate.
Manually prune unused VLANs to avoid broadcast propagation.
Use VTP Transparent mode, because there is little need for a com-
mon VLAN database in hierarchical networks.
Disable trunking on host ports, because it is not necessary. Doing so
provides more security and speeds up PortFast.
Consider implementing routing in the access layer to provide fast
convergence and Layer 3 load balancing.
Use Cisco STP Toolkit, which provides PortFast, Loop Guard, Root
Guard, and BPDU Guard.
Distribution layer
Use first-hop redundancy protocols. Hot Standby Router Protocol
(HSRP) or Gateway Load Balancing Protocol (GLBP) should be used
if you implement Layer 2 links between the access and distribution.
Use Layer 3 links between the distribution and core switches to al-
low for fast convergence and load balancing.
Build Layer 3 triangles, not squares.
Use the distribution switches to connect Layer 2 VLANs that span
multiple access layer switches.
Summarize routes from the distribution to the core of the network
to reduce routing overhead.
Use VSS as an option described below to eliminate the use of STP.
Core layer
Reduce the switch peering by using redundant triangle connections
between switches.
Use routing that provides a topology with no spanning-tree loops.
Use Layer 3 switches on the core that provide intelligent services
that Layer 2 switches do not support.
Use two equal-cost paths to every destination network.
