Dell PS4000 - Partially Redundant SAN Configurations

Dell EqualLogic Configuration Guide v11.3
31
4.3.3 Comparing Inter-Switch Connection Types
Table 17 provides details and recommendations for selecting interconnect options.
Interconnect Type
Primary Purpose
Analysis
Stacking
Create a larger,
logical switch
within an isolated
physical location.
Pros:
 Easier to manage multiple switches as single
switch
 Higher bandwidth than using link aggregation and
Ethernet
 Not limited by Ethernet standards
Cons:
 Proprietary, cannot be used to interconnect
switches from different vendors
 Increases cost of switch
 Stack bandwidth overload risk
Recommendation:
 Best way to scale a storage network in a single
location on a single subnet
 Provides lower latency and higher bandwidth
than inter-switch trunking
 Understand the stacking technology and limit
stack size in accordance with total throughput
requirements and connection counts.
Link Aggregation
Groups (LAG)
Create a data
path between
switches in one
location or subnet
with those in
another location
or subnet
Pros:
 Leverages Ethernet standard extensions
 Can be used to interconnect switches from
different vendors
 Can use Link Aggregation Protocols
(LACP/EtherChannel) to pool multiple 1GbE or
10GbE links into a single logical link providing
bandwidth and redundancy
Cons:
 Most solutions limited to 8 port link aggregation
group
 Spanning Tree Protocol must be used if more
than two switches are used causing some links to
be ―blocked‖ reducing bandwidth availability
 LAG bandwidth overload risk
Recommendation:
 Use when stacking is not available
 Use when connecting to aggregation/core
switching infrastructure
 Use when switches are from different vendors
Table 17 Stacking vs. Inter-Switch Trunking