Cisco CCNP / 사설사이트 BCMSN Test Tutorial: Configuring PortFast And BPDU Guard
In the CCNA experiments, you learned about PortFast and The difficulty it can cause if configured on the incorrect port! Ideal only for change ports connected on to only one host, PortFast lets a port jogging STP to go straight from blocking to forwarding method.
A Cisco router provides you with a warning if you configure PortFast:
SW1(config)#int rapidly 0/five
SW1(config-if)#spanning-tree portfast
%Warning: portfast need to only be enabled on ports connected to a
single host. Connecting hubs, concentrators, switches, bridges, and so forth…
to this interface when portfast is enabled, could potentially cause short term
bridging loops. Use with Warning
%Portfast continues to be configured on FastEthernet0/5 but will only
have influence in the event the interface is in a non-trunking method.
SW1(config-if)#
Don't just will the change alert you about the correct usage of PortFast, but you should put the port into entry manner prior to PortFast will acquire outcome.
Now, you’d think that might be ample of a warning, appropriate? But there's an opportunity – just an opportunity – that someone is going to deal with to attach a change to the port jogging Portfast. Which could result in two major complications, the first https://www.washingtonpost.com/newssearch/?query=토토사이트 currently being the formation of the switching loop. Keep in mind, The key reason why we have listening and Understanding modes is that will help avert switching loops. Another trouble is that there might be a different root bridge elected – and it may be a swap that isn’t even inside your community!
BPDU Guard guards against this disastrous risk. If any BPDU is available in on the port that’s managing BPDU Guard, the port are going to be shut down and put into mistake disabled state, revealed on the change as err-disabled. A port positioned in err-disabled condition have to be reopened manually.
BPDU Guard is off on all ports by default, and it is enabled as demonstrated below:
SW1(config-if)#spanning-tree bpduguard allow
It’s a smart idea to permit BPDU Guard on any port you’re operating PortFast on. There’s no cost in overhead, and it does reduce the potential of a switch sending BPDUs right into a port configured with PortFast – let alone the potential for a switch not less than your Management turning out to be a root change towards your network!