Downstream switches inherit timers from the root (of each VLAN)
debug spanning-tree event // root port, cost, state, TCN debug backbone
- BPDUgurad blocks incoming BPDUs.
- BPDUfilter blocks outgoing BPDUs.
bpduguard defaultwork in conjunction with
spanning-tree guard loopis similar to UDLD, but users STP BPDU keepalive.
show spanning-tree mst [detail]
interface f0/0 spanning-tree mst 1 cost 1 spanning-tree mst 2 port-p 0
All switches in the L2 transit path should know about the RSPAN remote-vlan, and the interconnections should be trunk. Remember to remove pruning for RSPAN VLAN from trunks.
IPphone tags voice traffic with CoS 5.
interface f0/1 switchport priority extended cos 1 ! show mls qos interface f0/1
switchport voice vlan dot1p instructs the IP-phone to apply VLAN0 and CoS 5, so both Voice & Data share the same VLAN.
switchport voice vlan automatically applies portfast.
mls qos trust device cisco–ipphone means only trust CoS if received from IP-phone which is detected by CDP.
switchport backup interface Fa0/16 switchport backup interface Fa0/16 preemption mode forced switchport backup interface Fa0/16 preemption delay 20
Fallback Bridging is the concept of bridging non-routed protocols between SVIs or native L3 router interfaces on switches. Similar to CBR and IRB on routers.
bridge 1 protocol vlan-bridge interface f0/1 bridge 1
- PVLAN requires Transparent VTP mode.
- Whenever a task asks us to optimize a switch for memory or routing, it means “sdm prefer routing“
- Macros do not accept “interface range”!
- When filtering traffic using mac-access-list remember to allow Spanning-tree and ARP stuff!
standby use-bia: not using the vMAC
standby version 2: Uses 188.8.131.52 for inter-router communications instead of 184.108.40.206
standby 1 ip 220.127.116.11 standby 1 priority : default is 100 standby 1 : not default standby 1 track 1 decrement // same as standby 1 track Serial0/1/0 20
Remember to add static arp for hosts when filtering ARP in LAB exam. (