
Explanation/Reference:
Explanation:
Access
The most feature-rich part of the campus network

Provides security, QoS, and IP Multicast to the network

Distribution
Routing boundary (Dynamic, summarization, static)

Enforces Policy within the network

Core
High level of availability, scalability, and fast convergence

Provides a limited set of services

Large-Building LANs
Large-building LANs are segmented by floors or departments. The building-access component serves one or more departments or floors. The building-distribution component serves one or more building-access components. Campus and building backbone devices connect the data center, building-distribution components, and the enterprise edge-distribution component. The access layer typically uses Layer 2 switches to contain costs, with more expensive Layer 3 switches in the distribution layer to provide policy enforcement. Current best practice is to also deploy multilayer switches in the campus and building backbone.
Cisco Enterprise Architecture Model
Core
Fast transport

High reliability

Redundancy

Fault tolerance

Low latency and good manageability

Avoidance of slow packet manipulation caused by filters or other processes

Limited and consistent diameter

Quality of service (QoS)

Distribution
Policy-based connectivity

Redundancy and load balancing

Aggregation of LAN wiring closets

Aggregation of WAN connections

QoS

Security filtering

Address or area aggregation or summarization

Departmental or workgroup access

Broadcast or multicast domain definition

Routing between virtual LANs (VLAN)

Media translations (for example, between Ethernet and Token Ring)

Redistribution between routing domains (for example, between two different routing protocols)

Demarcation between static and dynamic routing protocols

Access
Layer 2 switching

High availability

Port security

Broadcast suppression

QoS

Rate limiting

Address Resolution Protocol (ARP) inspection

Virtual access control lists (VACL)

Spanning tree

Trust classification

Power over Ethernet (PoE) and auxiliary VLANs for VoIP
Cisco Press CCDA 640-864 Official Certification Guide Fourth Edition, Chapter 3