Reference Guide

Stacking S-Series Switches | 705
The S50 and S25 systems support mixed stacking, as long as the units have the same FTOS version. The
S55 and S60 systems DO NOT SUPPORT mixed stacking. Stack only S55 systems together or only S60
systems together; do not stack them with any other system type. Figure 39-8 shows two common stacking
topologies, ring and cascade (also called daisy-chain). A ring topology provides some performance gains
and stack integrity.
Figure 39-8. Common S-Series Stacking Topologies (S50-type)
Facing the rear of an S-Series unit, stack-port are numbered from left to right, beginning with the highest
Ethernet port number (n) plus 1. For example, for a 48-port unit with two 12-Gigabyte stacking modules,
the stack-ports are 49, 50, 51, and 52.
To add a unit to an existing stack:
Note: The illustration below is an example to show ring and cascade topologies. Please refer to the
Installation document for your system type to view a diagram for the topology supported by your system.
Note: The S55 stacking modules are installed in the lower optional module slot (slot 0) and use ports 48
and 49.
Step Task Command Syntax Command Mode
1 Verify that each unit has the same FTOS version prior to
stacking them together.
show version
EXEC Privilege
2 Pre-configure unit numbers for each unit so that the
stacking is deterministic upon boot up.
stack-unit <stack-unit>
renumber <stack-unit>
EXEC Privilege
3 Configure the switch priority for each unit to make
management unit selection deterministic.
stack-unit <stack-unit>
priority <preference>
CONFIGURATION
4 Connect the units using stacking cables.
A
B
A
B
A
B
A
B
A
B
A
B
Ring Connection Cascade Connection
A
B