Troubleshooting router/switch performance


– By default, CEF and Fast Switching are enabled. (config-if)#no ip route-cache This command disables both Fast Switching and CEF. (config-if)#ip route-cache This command enables Fast Switching only. CEF is still disabled if we don’t activate it: To activate CEF ... Read More »


steps:– create the IP SLA monitor– configure it– schedule itCisco IOS did not show me help when I type interrogation mark. Yet, commands are accepted. Read More »



A good command reference for RIPng is found here. I didn’t know Cisco incorporated IPv6 into its CCNA courses! that demonstrates that Cisco is keeping the value of its certs high in the market. I’m proud to be studying networking ... Read More »



This post builds on the previous one, talking about IPv6. Router-idIf we don’t configure one, OSPFv3 will choose a Router ID in the same fashion as OSPFv2.After configuring basic OSPFv3, I see the following:If we remember with OSPFv2 over NBMA ... Read More »



– Remember to activate IPv6 routing and IPv6 CEFshow ipv6 interface brief … prefixfirst ping in IPv6:Link local, link global:debug ipv6 packet:show ipv6 routeConnected subnets are displayed as “Connected”. In our case, 2026::1/122 and 2026::34/122. The ip addresses of R3 ... Read More »

Troubleshooting OSPF


We will be exploring some OSPF troubleshooting scenarios and see how to solve the problems. Trouble ticket #1: Passive interface We have two routers R2 and R3 configured as OSPF routers. The problem is that router R3 can not get routes ... Read More »

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