Catalyst 6500 series switches support fault resistance, because it allows a redundant supervisor engine to take over if the primary supervisor engine fails. Cisco Non Stop Forwarding (NSF) works with Stateful SwitchOver (SSO) in order to minimize the amount of time a network is unavailable to its users after a switchover while IP packets continue to be forwarded. Recommendations Non Stop Forwarding is required for supervisor switchover convergence at sub-second time. Use default Hello and Dead timers for EIGRP / OSPF protocols when you run in a VSS environment. If you run the system with modular Cisco IOS software, it is recommended to go for larger value OSPF Dead timer. EIGRP OSPF
Non Stop Forwarding
Switch(config)# <b>router eigrp 100</b>
Switch(config-router)# <b>nsf</b>
Switch# <b>show ip protocols</b><br />*** IP Routing is NSF aware ***<br /><br />Routing Protocol is "eigrp 100"<br /><i><font color="#0000ff">!--- part of the output truncated</font><br /></i><b>EIGRP NSF-aware</b> route hold timer is 240s<br /><i><font color="#0000ff">!--- indicates that EIGRP is configured to be NSF aware</font><br /></i><i><font color="#0000ff">!--- part of the output truncated</font><br /></i><br /><b>EIGRP NSF enabled</b><br /><i><font color="#0000ff">!--- indicates that EIGRP is configured to be NSF capable</font><br /></i><i><font color="#0000ff">!--- rest of the output truncated</font><br /></i>
Switch(config)# <b>router ospf 100</b><br />Switch(config-router)# <b>nsf</b>
Switch# <b>show ip ospf</b><br />Routing Process "ospf 100" with ID 10.120.250.4<br />Start time: 00:01:37:484, Time elapsed: 3w2d<br /><i><font color="#0000ff">!--- part of the output truncated</font><br /></i><b>Supports Link-local Signalling (LLS)</b><br /><i><font color="#0000ff">!--- indicates that OSPF is configured to be NSF aware</font><br /></i><i><font color="#0000ff">!--- part of the output truncated</font><br /></i><b>Non-Stop Forwarding enabled, last NSF restart 3w2d ago (took 31 secs)</b><br /><i><font color="#0000ff">!--- indicates that OSPF is configured to be NSF capable</font><br /></i><i><font color="#0000ff">!--- rest of the output truncated</font><br /></i><br />




