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Software Configuration Guide—Release 12.2(25)SG
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Chapter 6 Configuring Supervisor Engine Redundancy Using RPR and SSO
Understanding Supervisor Engine Redundancy
Because the redundant supervisor engine recognizes the hardware link status of every link, ports that
were active before the switchover will remain active, including the uplink ports. However, because
uplink ports are physically on the supervisor engine, they will be disconnected if the supervisor engine
is removed.
If the active supervisor engine fails, the redundant supervisor engine become active. This newly active
supervisor engine uses existing Layer 2 switching information to continue forwarding traffic. Layer 3
forwarding will be delayed until the routing tables have been repopulated in the newly active supervisor
engine.
SSO supports stateful switchover of the following Layer 2 features. The state of these features is
preserved between both the active and redundant supervisor engines:
• 802.3
• 802.3u
• 802.3x (Flow Control)
• 802.3ab (GE)
• 802.3z (Gigabit Ethernet including CWDM)
• 802.3ad (LACP)
• 802.1p (Layer 2 QoS)
• 802.1q
• 802.1X (Authentication)
• 802.1D (Spanning Tree Protocol)
• 802.3af (Inline power)
• PAgP
• VTP
• Dynamic ARP Inspection
• DHCP snooping
• IP source guard
• IGMP snooping (versions 1 and 2)
• DTP (802.1q and ISL)
• MST
• PVST+
• Rapid-PVST
• PortFast/UplinkFast/BackboneFast
• BPDU guard and filtering
• Voice VLAN
• Port security
• Unicast MAC filtering
• ACL (VACLS, PACLS, RACLS)
• QOS (DBL)
• Multicast storm control/broadcast storm control
