Information Technology Reference
In-Depth Information
Defining the DC Aggregation Layer
The data center aggregation (distribution) layer aggregates Layer 2/Layer 3 links from the
access layer and connects using upstream links to the data center core. Layer 3 connectiv-
ity is typically implemented between the data center aggregation and the data center core
layers. The aggregation layer is a critical point for security and application services. The
Layer 4 security and application services in the data center aggregation layer include
server load balancing, SSL offloading, firewalling, and IPS services. These services main-
tain connection and session state for redundancy purposes and are commonly deployed in
pairs using Cisco Catalyst 6500 service modules. This design reduces the total cost of
ownership (TCO) and eases the management overhead by simplifying the number of de-
vices that must be managed.
Key
To p i c
The highlighted section in Figure 4-10 illustrates the data center aggregation layer.
10 Gigabit Ethernet
Gigabit Ethernet or Etherchannel
Backup
Campus Core
DC
Core
DC
Aggregation
Aggregation 2
Aggregation 3
Aggregation 4
DC
Access
Layer 2 Access with
Clustering and NIC
Te a m i n g
Blade Chassis with
Passthru Modules
Mainframe
with OSA
Blade Chassis
with Integrated
Switch
Layer 3 Access with
Small Broadcast Domains
and Isolated Servers
Figure 4-10
Data Center Aggregation Layer
