Specifications

DATA CENTER BEST PRACTICES
SAN Design and Best Practices 12 of 84
In addition to redundant fabrics, redundant links should be placed on different blades, different ASICs, or at
least different port groups whenever possible, as shown in Figure 3. (Refer to Appendix C to determine trunk
groups for various port blades. For more details, see the Brocade Fabric OS Administrator’s Guide.) Whatever
method is used, it is important to be consistent across the fabric. For example, do not place ISLs on lower port
numbers in one chassis (as shown in the left diagram in Figure 3) and stagger them in another chassis (as
shown in the right diagram in Figure 3). Doing so would be mismatched ISL placement.
fig03_SAN_Design
Distribute devices across switch port cards
ISLs/
trunks
ISLs
SAN
devices
SAN
devices
ISLs
SAN
devices
Distribute devices
across ports
Figure 3. Examples of distributed ISL placement for redundancy.
Note: In Figure 3, ISL trunks are placed on separate Application-Specific Integrated Circuits (ASICs) or port groups.
It is important to match ISL placement between devices and across fabrics to ensure simplicity in design and
assist in problem determination.
ICL Connectivity for Brocade DCX and DCX 4-S Only
The Brocade DCX Backbone platform provides an additional method of interconnect called
Inter-Chassis Links (ICLs). ICL ports are located on the core blades and provide 512 Gbps of bandwidth per
chassis (equivalent to a 64-port blade) for additional inter-chassis connectivity. Two or three chassis can be
interconnected (see Figures 4 and 5 for examples), freeing up front-end ports for connecting
end devices.
A SAN topology should be evaluated for the feasibility of using ICLs between chassis to free up regular
blade ports.
fig04_SAN_Design
Figure 4. Examples of two-chassis ICL congurations: Brocade DCX to DCX (left) and Brocade DCX-4S Backbone
to DCX (right).