A two-tier campus LAN uses access and distribution layers without a separate core layer. This collapsed-core design combines core and distribution functions in the second layer. section 15.2.1
The architecture divides operational responsibilities between two layers:
- Access switches connect end hosts such as PCs, phones, cameras, door locks, servers, wireless access points, and other devices; common features include QoS marking, Port Security, DHCP Snooping, DAI, and PoE. section 15.2.1
- Distribution switches aggregate access-switch connections, typically connect to the WAN and internet, and provide redundancy through multiple switches and connections. section 15.2.1
- The distribution layer commonly borders Layer 2 and Layer 3: access links are Layer 2 trunks, while external connections use Layer 3 routed ports. section 15.2.1
Distribution SVI configuration
A distribution switch can configure VLAN 10, assign an IP address, provide an HSRP virtual IP, raise HSRP priority, and enable OSPF on the SVI.
