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| Uplink Module and Stacking
Aruba S3500 Series Wired Access Point
| Installation Guide
Stacking
The Stacking feature enables simplified management by presenting a set of Mobility Access Switches as one
entity, and reduces the operational complexity of managing multiple redundant links between access and
distribution layer switches. Since the
stack
appears as one network node, loop prevention protocols are not
required.
The Stack is a set of interconnected Mobility Access Switches using stacking ports to form a stack. A
stacking port is a physical port provisioned to run the stacking protocol. In factory default settings for
Mobility Access Switches, 10 Gigabit uplink ports 2 and 3 on the uplink module are pre-provisioned to be
stacking ports. Once a port is provisioned for stacking, it is no longer available to be managed as a network
port. A stacking port can only be connected to other Mobility Access Switches running the Aruba Stacking
Protocol (ASP).
The Stacking Protocol
Each Mobility Access Switch runs a stack manager process that is responsible for running the Stacking
protocol. The Stacking protocol is responsible for automatically:
Identifying the stack neighbors and determining the stack topology.
Assigning the switch’s member ID to each member of the stack.
Assigning each member of the stack a role; Primary, Secondary or Line Card.
Setting up optimized communication path/channel between the stack members. This path/channel
transports user data packets and the switch’s own control packets.
Converges the stacking topology during a stack link or stack member failure eventt; users and traffic are
automatically re-routed via a different path.
Auto Discovery
The Stacking protocol exchanges information between Mobility Access Switches that are connected to each
other and without any prior stacking related configuration. The protocol exchanges information between
the different stack members, runs distributed election algorithm, and elects a Primary and Secondary
members among the stack members. The Primary then assigns stack member IDs to himself others.
Planning a Stack
Aruba recommends using a ring topology (
Figure 27
) for a stack consisting of S3500s. This configuration
provides connectivity to all members as well as redundancy in the event a cable failure.
Consider the following while planning your stack:
ArubaOS supports up to eight Mobility Access Switches in a single stack. The stack can be a mixture of
24 and 48-port switches.
Cable Length: Depending on your configuration, you might need cables of different length.
The sequence in which you initially power on the S3500s in your stack determines their member ID. For
example, the first S3500 to boot up is assigned member ID 0 and the second S3500 is assigned member
ID 1. Therefore, if you want your S3500s to be assigned particular IDs, power them on in that order.
Upgrade your Mobility Access Switch to the most recent software release. Stacking is supported in ArubaOS 7.1
and newer. All the members in your Mobility Access Switches, in your stack, must run the same version of
ArubaOS.
All values and setting described in the following sections are the default values and settings.
