Core-distribution layer

As explained in Acing the CCNA Exam: Volume 2 Advanced Networking and Security

A collapsed core is a campus network architecture in which the core and distribution functions are combined into one layer.

A core-distribution layer combines the campus core and distribution functions in a two-tier LAN, leaving access switches as the only separate layer. It aggregates access connections and typically connects the LAN to the corporate WAN or internet. section 15.2.1

Recognize the layer by its operational roles:

• Connects to access switches through Layer 2 trunk links. section 15.2.1
• Connects to external network areas through Layer 3 routed ports. section 15.2.1
• Uses multilayer switches, redundant default gateways, and routing protocols such as HSRP and OSPF. section 15.5

SVI configuration

A distribution switch can configure VLAN 10 with an IP address, assign an HSRP virtual IP and priority, and enable OSPF: interface vlan 10; ip address 10.0.0.2 255.255.255.0; standby 1 ip 10.0.0.1; standby 1 priority 105; ip ospf 1 area 0.

Figure 15.3 A two-tier campus LAN consists of access and distribution layers.

Use the topology figure to visualize access switches aggregated into a two-tier core-distribution design. section 15.2.1

How Acing the CCNA Exam: Volume 2 Advanced Networking and Security covers it

How deep it goes

Defines layer roles, Layer 2–Layer 3 boundaries, redundancy, and representative SVI configuration.

Examples

Uses two-tier campus topologies and Cisco CLI for VLAN interfaces, HSRP, and OSPF.

What you can do after

Configure SVIs with addressing, HSRP gateway redundancy, and OSPF routing on a distribution switch.

How it connects

Aggregates access switches, connects WAN and internet networks, and supports HSRP and OSPF.

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Related concepts

• two-tier architectureequivalent to · A two-tier architecture is a hierarchical network design organized into two functional layers.
• distribution layerimplements · A distribution layer is the campus-network layer that aggregates access switches and provides policy, connectivity, and path control between access and core layers.
• core layerhas part · A core layer is the campus-network layer that aggregates connections between distribution layers in large LANs.

This explainer was generated by Manning's knowledge graph from the text of Acing the CCNA Exam: Volume 2 Advanced Networking and Security. The section links point to the parts of the book it draws on.