Cisco Catalyst 3850 Deployment Manual page 29

The Cisco IOS XE Software high-availability framework is enabled by default on Cisco Catalyst 3850 Switches
when they are deployed in StackWise-480 mode. The newly provisioned Cisco Catalyst 3850 Switch automatically
discovers and dynamically joins the stack ring. The Cisco StackWise-480 technology features system-level N:1
high availability. Adding switches to and removing switches from a stack do not affect the active and hot standby
roles already in effect in the stack.
To enable stateful switchover (SSO) resiliency in Cisco StackWise-480 mode, you must configure each switch with
the same Cisco IOS XE Software version and license. Figure 7 illustrates system roles and operation of Cisco
StackWise-480 when you add Cisco Catalyst 3850 Switches to a stack.
Figure 7.
The unique high-availability architecture in the Cisco StackWise-480 design enables distributed network services,
such as flexible NetFlow, quality of service (QoS), and more, as well as providing system-level redundancy for all
stack-member switches. During a complete stack reload, all switches participate in an election process to
determine assignment of the active and standby roles. Several criteria, including switch priority and MAC
addresses, are compared to elect the active and standby switches in the stack.
To view information about switches in the stack (model, serial number etc), you can use show module command:
Switch# show module
Switch
------
1
2
3
4
To assign the active and standby roles to specific switches, configure the default switch priority for all switches in
the stack. You configure the priority once, usually during the initial configuration process, but you can change the
configuration at any time. The configured switch priorities are immediately set in the boot loader configuration of
each switch in the stack. This means the switch priority configuration cannot be verified from the startup or running
configuration because it is programmed into different configuration components. The switch priority configuration in
boot loader is parsed during the boot cycle, not read from the startup configuration stored in NVRAM.
© 2015 Cisco and/or its affiliates. All rights reserved. This document is Cisco Public Information.
Plug-and-Play Cisco Catalyst 3850 Switch System Role Designation
Ports Model
----- -----
32 WS-C3850-24S
56 WS-C3850-48P
32 WS-C3850-24P
32 WS-C3850-24U
Serial No. MAC address
----------- -----------
FOC1852U0NR c472.954f.5380
FOC1717V0NH 44ad.d96d.b480
FOC1824X086 00e1.6d52.c600
FOC1729Z182 f84f.576f.e100
Hw Ver. Sw Ver.
------ --------
V01 03.07.00.E
V01 03.07.00.E
V03 03.07.00.E
V01 03.07.00.E
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