In data centers today, a three-tiered architecture has access, aggregation, and core layers, as described below.
Access Switches
The access layer is the first tier or edge of the data center. It is the place where end devices such as servers and storage attach to the wired or wireless portion of the network. The servers are front-end to the access and back-end to the Ethernet- and Fibre Channel-based storage.
Aggregation Switches
The aggregation layer has a unique role: it acts as a services and control boundary between the access and core. Both access and core are essentially dedicated special-purpose layers. The access layer is dedicated to meeting the functions of end-device connectivity and the core layer is dedicated to providing non-stop connectivity across the entire network. The aggregation layer, on the other hand, serves several functions. It is an aggregation point for all of the access switches; it can be scaled out and acts as an integral member of the access-distribution block providing connectivity and policy services for traffic flows within the access-distribution block. As an element in the core of the network, it participates in the core routing design.
Core Switches
The core layer provides a very limited set of services and is designed to be highly available and operate in an always-on mode. The core layer is a gateway with high-speed connectivity to external entities, such as the WAN, intranet, and Internet. The data center core is a Layer 3 domain in which efficient and expeditious forwarding of packets is the fundamental objective. To this end, the data center core is built with high-bandwidth links (10 GbE) and employs routing best practices to optimize traffic flows. Note that the core should not implement any complex policy services, nor should it have directly-attached user or server connections. The core should have a minimal control plane configuration combined with highly available devices configured with the physical redundancy to provide for non-stop service.
Load Balancers

Load balancing is a computer networking methodology to distribute workload across multiple servers, network links, processing systems, disk drives and other IT resources. This helps IT network designers achieve balanced resource utilization, maximizes network throughput, and avoids overloading any particular asset. In addition, by leveraging load balancing, network designers increase reliability by hedging against single points of failure by creating multiple paths for data flow and processing in case any single point (i.e. individual server or switch) fails.
As a consultancy, PTS performs comprehensive needs analysis, performs a complete assessment of possible solutions from best-in-class manufacturers, and designs the most appropriate switching approach to meet the client requirements prior to recommending a switching solution from any particular manufacturer. Deployment scenarios range from internet backbone to server aggregation to collapsed enterprise backbone to aggregation to access.
To learn more about PTS recommended Routing & Switching Solutions, contact us or visit (in alphabetical order):

Access Switches (in alphabetical order)
- Arista Networks 7050 Series Data Center Switch
- Arista Networks 7100 Series Data Center Switch
- Blade Network Technologies RackSwitch G8000
- Blade Network Technologies RackSwitch G8100
- Brocade FCX Series
- Brocade VDX6730 Data Center Switch
- Enterasys N-Series
- Force10 C-Series
- Force10 S-Series
- Juniper Networks EX Series Ethernet Switching Solutions

Aggregation Switches (in alphabetical order)
- Arista Networks 7050 Series Data Center Switch
- Arista Networks 7100 Series Data Center Switch
- Arista Networks 7500 Series Data Center Switch
- Blade Network Technologies RackSwitch G8100
- Brocade BigIron RX
- Brocade VDX6730 Data Center Switch
- Enterasys N-Series
- Enterasys S-Series
- Force10 C-Series
- Force10 ExaScale E-Series
- Force10 TeraScale E-Series
- Force10 S-Series
- Juniper Networks EX Series Ethernet Switching Solutions
- Arista Networks 7500 Series Data Center Switch
- Brocade BigIron RX
- Enterasys N-Series (SMB network core)
- Enterasys S-Series
- Force10 ExaScale E-Series
- Force10 TeraScale E-Series
- Force10 S-Series
- Juniper Networks EX Series Ethernet Switching Solutions
- Juniper Networks QFabric Family of Switch Solutions
Load Balancers (in alphabetical order)
Routers (in alphabetical order)
To learn more about PTS consulting services to support Data Center Routing & Switching Solutions, contact us or visit:
- PTS Data Center Planning & Pre-Design
- Computational Fluid Dynamics (CFD) Services
- Data Center Energy Usage Assessment Service
- Data Center Power & Cooling Systems Analysis
- Data Center Availability & Risk Assessment
- Data Center Design Commissioning
- IT Implementation Services
- Data Center Support Infrastructure Equipment Services
- Raised Floor Cooling Analysis
- The Challenges of Data Center Cooling
- Help With High Density Cooling
- Data Center Feasibility Analysis
- Data Center Site Assessment
- Thermography Assessment Service
- PTS Virtualization Strategies & Assessments
- IT Business Continuity & Disaster Recovery
- Data Center Routing and Switching Planning & Feasibility
- Data Center Server Planning & Feasibility
- Data Center Storage Area Network (SAN) and Data Protection Planning & Feasibility