Cisco Catalyst 4500 series Administration Manual page 458

Supervisor Engine Redundancy Guidelines and Restrictions
If SSO mode cannot be established between the active and standby supervisor engines because of
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an incompatibility in the configuration file, a mismatched command list (MCL) is generated at the
active supervisor engine and a reload into RPR mode is forced for the standby supervisor engine.
Subsequent attempts to establish SSO, after removing the offending configuration and rebooting the
standby supervisor engine with the exact same image, might cause the
C4K_REDUNDANCY-2-IOS_VERSION_CHECK_FAIL and
ISSU-3-PEER_IMAGE_INCOMPATIBLE messages to appear because the peer image is listed as
incompatible. If the configuration problem can be corrected, you can clear the peer image from the
incompatible list with the redundancy config-sync ignore mismatched-commands EXEC
command while the peer is in a standby cold (RPR) state. This action allows the standby supervisor
engine to boot in standby hot (SSO) state when it reloads.
Here are the steps:
Step 1 Clear the offending configuration (that caused an MCL) while the standby supervisor engine is in
standby cold (RPR) state.
Enter the redundancy config-sync ignore mismatched-commands EXEC command at the active
Step 2
standby supervisor engine.
Perform write memory.
Step 3
Reload the standby supervisor engine with the redundancy reload peer command.
Step 4
• RPR and SSO requires Cisco IOS-XE Release 3.1.0SG and later releases.
SSO is not supported if the IOS-XE software is running in the LAN Base mode.
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WS-C4507R-E, WS-C4510R-E, WS-C4507R+E, and WS-C4510R+E are the only Catalyst 4500
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series switches that support Supervisor Engine 7-E, Supervisor Engine 7L-E, and Supervisor Engine
8-E redundancy.
• In RPR or SSO mode,
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SSO requires both supervisor engines in the chassis to have the same components (model and
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memory), and to use the same Cisco IOS XE software image.
The active and standby supervisor engines in the chassis must be in slots 3 and 4 for 7-slot chassis
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and slot 5 and 6 for 10-slot chassis.
Each supervisor engine in the chassis must have its own flash device and console port connections
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to operate the switch on its own.
Each supervisor engine must have a unique console connection. Do not connect a Y cable to the
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console ports.
Supervisor engine redundancy does not provide supervisor engine load balancing.
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The Cisco Express Forwarding (CEF) table is cleared on a switchover. As a result, routed traffic is
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interrupted until route tables reconverge. This reconvergence time is minimal because the SSO
feature reduces the supervisor engine redundancy switchover time from 30+ seconds to subsecond,
so Layer 3 also has a faster failover time if the switch is configured for SSO.
Software Configuration Guide—Release IOS XE 3.6.0E and IOS 15.2(2)E
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Chapter 11 Configuring Supervisor Engine Redundancy Using RPR and SSO on Supervisor Engine 7-E, Supervisor
with Supervisor Engine 7-E and 7L-E, only the first two uplinks on each supervisor engine are
available. The second two uplinks are unavailable.
with Supervisor Engine 8-E, only the first four uplinks on each supervisor engine are available
provided a 47xx line card is inserted on slot 10. The second set of four uplinks are unavailable.
With Supervisor Engine 8-E in a 4510 chassis, the last slot is restricted to 47xx line cards only.
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