Specifications

Copyright © 2009, Juniper Networks, Inc. 19
DESIGN GUIDE - Data Center LAN Connectivity Design Guide
Small Data Center LANs1.
For small data centers with few devices and a simple topology, Juniper recommends using Layer 2 at the access
layer. Such a LAN design has fewer devices to manage and eliminates the need for STP, increasing convergence
response while reducing CAPEX and OPEX.
Most Data Center LANs2.
Since the LAN design for most highly available data centers has a series of redundant devices and connections,
Juniper Networks recommends using Layer 3 to the access layer, which is included in the EX Series at no extra
cost. In this design, Juniper recommends switches with Virtual Chassis technology to deliver high performance
load balancing and simplified device management. This equates to lower CAPEX and OPEX compared to
competing solutions.
Physical Deployment: Top-of-Rack vs. End-of-Row
In traditional top-of-rack (TOR) or the end-of-row (EOR) deployments, fixed-chassis access-layer switches are used to
provide high-performance, HA services and high-density GbE and 10 GbE connections to servers in the data center.
Figure 9: Top-of-rack vs. end-of-row switch deployments
Top-of-Rack (TOR)
This configuration places high-performance switches at the top of the server rack in a row of servers in the data
center. Cabling run lengths are minimized in this deployment and simpler than end-of-row (EOR) configurations.
However, each legacy switch must be managed individually, complicating operations and adding expense as multiple
discreet 24- or 48-port switches are required to meet connectivity needs in TOR configurations.
End-of-Row (EOR)
In this configuration, high-density switches are placed at the end of a row of servers in the data center. Traditional
modular chassis switches have commonly been used in this deployment, where cabling is quite complex. Switch
port utilization is suboptimal with traditional chassis-based switches, and most consume a great deal of power and
cooling, even when not fully configured or utilized. In addition, these large chassis-based switches are usually large
and take up a great deal of valuable data center space.
Storage Connectivity
Increased productivity and intelligent decision making both rely on instant access to valuable business data. With
a critical impact on the bottom line, enterprise data storage must be fast, reliable and always available. It also
must be secured against unauthorized access, unwanted modification and loss. Additionally, it must easily scale to
meet compliance regulations and maintain important business records. Storage networks such as Fibre Channel,
InfiniBand, iSCSI and NDAS should be included as part of the data center design. Virtualization technologies may be
used to provide seamless and unlimited storage. Critical application servers, such as those from NetApp, directly
connect to the storage devices through a separate host bus adapter (HBA) to ensure fast access to data. Other
servers connect via Ethernet or another interface to get access to the storage facilities. For high-performance data
access needs, iSCSI solutions with TCP Offload capabilities or using 10 GbE for NAS solutions should be considered.