Tuesday, August 25, 2009


You know what I keep freakin forgetting? Dumbest shit in the world actually.....during my switch configs I ALWAYS forget the stinking ip default-gateway command!?! Thats like switching 101...I pick up pretty quickly after something fails to come back from the switch..but I mean damn. This is like the 10 time in 3 weeks I have done it. Need to embed that into my head...so I wrote it here :)

So I did an HSRP lab tonight. It was pretty fun. I see where the BCMSN lab portfolio is going.....type...repeat...type....repeat. Thats ok though, I figure that it will be etched into my brain via laser beam once completed. So, basic config:

I know that diagram is juvinile...but I dont have visio installed at home! So, better a paint visio than nothing at all. So quit your bitching and snickering.

Then a couple of nodes hooked up to each on a separate vlan. I had vlans 1, 10, 20, 30, 40 running on all of the switches. I distributed the vlans from switch 1 via vlan trunking protocol version 2. So....switches 1 and 2 are 3550 layer 3 switches. The book had me make sw1 the active hsrp router for 1, 10, and 20. SW2 was the standby for those, and the active router for....dadada, you guessed it 30 and 40. Basic config looked like this under the svi interfaces:

standby 1 ip 172.16.x.x
standby 1 preempt
standby 1 priority 150 (on the active switch, remember that 100 is the default)

So all went as planned. The correct switches became the active router for the proper vlans, the other became the standby. I manipulated the hello and hold timers on vlan 40, on the active router, and noticed that it actually passed these values on to the standby router...cool shit.

Umm, I then went off track and started doing my own thing. I manipulated spanning tree so that switch2 would become the root switch for its vlans (30,40). SW1 was the root switch by default for all vlans because of its low mac address. I used this command...I think:
spanning-tree vlan 30,40 root primary (thats off the top of my head so I think its accurate)

Then finally I tracked the port channel on SW1 on its active vlan interfaces (1, 10, 20).
(config)int range vlan 1, vlan 10, vlan20
(config-if-range) standby 1 track port-channel 1 51 (decrement to drop priority below 100 so that SW2 will take over as active router)

Something I noticed was that I had and active/active state for about 45 seconds where both switches were the active switch for all vlans. Finally SW2 took over the active role however. Need to look up some literature on this anomaly. Guess which vlan came out of active/active first?.....the one I lowered the hello and hold timers on! 40

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