Cisco Systems 3560X Manual De Usuario

The switch or switch stack supports two levels of nonstop forwarding (NSF):

The IP-services feature set supports OSPF NSF Awareness supported for IPv4. When the neighboring 
router is NSF-capable, the Layer 3 switch continues to forward packets from the neighboring router 
during the interval between the primary Route Processor (RP) in a router crashing and the backup RP 
taking over, or while the primary RP is manually reloaded for a non-disruptive software upgrade. 

This feature cannot be disabled. For more information on this feature, see the “OSPF Nonstop 
Forwarding (NSF) Awareness” section of the Cisco IOS IP Routing Protocols Configuration Guide, 
Release 12.4

 at this URL: 

The IP-services feature set also supports OSPF NSF-capable routing for IPv4 for better convergence and 
lower traffic loss following a stack master change. When a stack master change occurs in an OSPF 
NSF-capable stack, the new stack master must do two things to resynchronize its link-state database with 
its OSFP neighbors:

Release the available OSPF neighbors on the network without resetting the neighbor relationship.

Reacquire the contents of the link-state database for the network.

After a stack master change, the new master sends an OSPF NSF signal to neighboring NSF-aware 
devices. A device recognizes this signal to mean that it should not reset the neighbor relationship with 
the stack. As the NSF-capable stack master receives signals from other routes on the network, it begins 
to rebuild its neighbor list.

Timers shortest path first (spf)

spf delay: 5 seconds.; spf-holdtime: 10 seconds.

Virtual link

No area ID or router ID defined.

Hello interval: 10 seconds.

Retransmit interval: 5 seconds.

Transmit delay: 1 second.

Dead interval: 40 seconds.

Authentication key: no key predefined.

Message-digest key (MD5): no key predefined.

1. NSF = Nonstop forwarding
2. OSPF NSF awareness is enabled for IPv4 on Catalyst 3750-E and 3560-E switches running the IP services feature set.