Cisco WS-SUP32-GE-3B - Supervisor Engine 32 Software Configuration Manual page 86

Understanding NSF with SSO Supervisor Engine Redundancy
Neighboring routers do not detect a link flap
•
Because the interfaces remain up throughout a switchover, neighboring routers do not detect a link
flap (the link does not go down and come back up).
Prevents routing flaps
•
Because SSO continues forwarding network traffic in the event of a switchover, routing flaps are
avoided.
• No loss of user sessions
User sessions established before the switchover are maintained.
Cisco NSF with SSO has these restrictions:
For NSF operation, you must have SSO configured on the device.
•
NSF with SSO supports IP Version 4 traffic and protocols only.
•
Enhanced Object Tracking is not SSO-aware and cannot be used with Hot Standby Routing Protocol
•
(HSRP), Virtual Router Redundancy Protocol (VRRP), or Gateway Load Balancing Protocol
(GLBP) in SSO mode.
• The HSRP is not SSO-aware, meaning state information is not maintained between the active and
redundant supervisor engine during normal operation. HSRP and SSO can coexist but both features
work independently. Traffic that relies on HSRP may switch to the HSRP standby in the event of a
supervisor engine switchover.
The Gateway Load Balancing Protocol (GLBP) is not SSO-aware, meaning state information is not
•
maintained between the active and redundant supervisor engine during normal operation. GLBP and
SSO can coexist but both features work independently. Traffic that relies on GLBP may switch to
the GLBP standby in the event of a supervisor engine switchover.
The Virtual Redundancy Routing Protocols (VRRP) is not SSO-aware, meaning state information is
•
not maintained between the active and redundant supervisor engine during normal operation. VRRP
and SSO can coexist but both features work independently. Traffic that relies on VRRP may switch
to the VRRP standby in the event of a supervisor engine switchover.
Multiprotocol Label Switching (MPLS) is not suported with Cisco NSF with SSO; however, MPLS
•
and NSF with SSO can coexist. If NSF with SSO is configured in the same chassis with MPLS, the
failover performance of MPLS protocols will be at least equivalent to RPR while the supported NSF
with SSO protocols still retain the additional benefits of NSF with SSO.
All neighboring devices participating in BGP NSF must be NSF-capable and configured for BGP
•
graceful restart.
OSPF NSF for virtual links is not supported.
•
All OSPF networking devices on the same network segment must be NSF-aware (running an NSF
•
software image).
For IETF IS-IS, all neighboring devices must be running an NSF-aware software image.
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IPv4 Multicast NSF with SSO is supported by the PFC3B only.
•
The underlying unicast protocols must be NSF-aware in order to use multicast NSF with SSO.
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Bidirectional forwarding detection (BFD) is not SSO-aware and is not supported by NSF with SSO.
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Catalyst Supervisor Engine 32 PISA Cisco IOS Software Configuration Guide, Release 12.2ZY
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Chapter 5 Configuring NSF with SSO Supervisor Engine Redundancy
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