Stacking Considerations - Avaya 3500 Series Getting Started

Stacking considerations

The following section contains the stacking considerations for ERS 3549GTS and ERS 3549GTS-
PWR+ models. As these switch models support 49 GigE ports and a single SFP+ interface, you
must consider the following factors when implementing these models into larger stack designs.
• Placement of ERS 3549 models within the stack
• SFP and SFP+ trunk/uplink design
• Trunk and access port utilization
• Use of 10G interfaces
Note:
The Avaya recommendations made in this section are based on the requirements of a typical
Unified Communications-enabled office. Individual requirements or considerations may vary.
Placement of ERS 3549 models within the stack
The ERS 3549 has 120Gbps switching capacity, which provides for higher aggregation of access
ports and available throughput between hosts. However, when placing the ERS 3549 in mixed
stacked configurations with fewer ports, Avaya recommends that you place the ERS 3549s in an
alternating sequence. This allows for the shortest possible path between stacking ports and makes
the stack configuration as efficient as possible.
SFP+ trunk design
Avaya recommends that you alternate MLT or LAG members to every other switch in the stack
when using 10G interfaces. This allows a shorter path to be taken across the stacking backplane by
access port traffic that more frequently sends data across a trunk link rather than to another access
port. Additionally, this configuration supports the need for communication between hosts connected
to access ports and is within the performance requirements of the full duplex access port bandwidth,
satisfying common host-to-host communication needs.
Consideration must also be given to the aggregate bandwidth requirements of the access ports that
are at, or over, stack capacity. You can use additional SFP+ interfaces in additional groups as
required, such as for fault tolerance when connecting to a network core. However, you must keep
this relative to the overall available bandwidth of the stack.
SFP trunk/uplink design
You can use fiber trunks to create connections to network servers or create MLTs and LAGs when
resilient trunks to a network core are required. As the bandwidth of these SFP interfaces is typically
less than 1Gbps, few considerations are required for these types of MLTs. However, Avaya still
recommends that you alternate these trunk interfaces equally across the stack. There is less of a
need to limit the number of these trunks as the primary constraint is the number LAG groups
supported by the switch.
Trunks and Access Port Utilization
You must consider the aggregation of all trunk and access port traffic such that the entire design
delivers the proper amount of total bandwidth to the entire network.
July 2015
Comments on this document? infodev@avaya.com
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