Dell EqualLogic PS4000, Configuration Manual

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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