Technical information

41 EqualLogic Configuration Guide | Version 15.2 | August 2014
Table 16 Stacking versus LAG
Interconnect
type
Primary purpose
Analysis
Stacking
Create a larger,
logical switch within
an isolated physical
location.
Advantages:
 Easier to manage multiple switches as single switch
 Possibly higher bandwidth than using link aggregation and
Ethernet
 Not limited by Ethernet standards
 Firmware upgrades will reset the entire stack
Concerns:
 Proprietary, cannot be used to interconnect switches from
different vendors
 Increases cost of switch
 Stack bandwidth overload risk
Recommendation:
 Simplest way to scale a storage network in a single location
on a single subnet
 May provide lower latency and higher bandwidth than a LAG
 Understand the stacking technology and limit stack size in
accordance with total throughput requirements and
connection counts.
LAG
Create a data path
between switches in
one location or
subnet with those in
another location or
subnet
Advantages:
 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
 Can upgrade switch firmware on each switch independently
Concerns:
 Some solutions limited to eight port link aggregation group
 Spanning Tree Protocol must be used if more than two
switches are used causing some links to be “blocked” and
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
 Use when highest availability is required