Cisco CCNP / BCMSN Test Tutorial: Configuring PortFast And BPDU Guard
Inside your CCNA experiments, you acquired about PortFast 먹튀검증 and The difficulty it might cause if configured on the wrong port! Appropriate just for change ports related on to only one host, PortFast makes it possible for a port functioning STP to go directly from blocking to forwarding method.
A Cisco router offers you a warning whenever you configure PortFast:
SW1(config)#int quickly 0/5
SW1(config-if)#spanning-tree portfast
%Warning: portfast need to only be enabled on ports linked to a
solitary 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 CAUTION
%Portfast continues to be configured on FastEthernet0/5 but will only
have outcome when the interface is in a non-trunking manner.
SW1(config-if)#
Not simply will the swap alert you about the appropriate utilization of PortFast, but you need to put the port into access mode right before PortFast will choose outcome.
Now, you’d feel that would be adequate of a warning, right? But there's a chance – just an opportunity – that somebody will control to connect a change to your port working Portfast. That can result in two major troubles, the 1st currently being the formation of the switching loop. Keep in mind, The main reason We've got listening and Finding out modes is that can help stop switching loops. The next difficulty is usually that there may be a whole new root bridge elected – and it http://query.nytimes.com/search/sitesearch/?action=click&contentCollection®ion=TopBar&WT.nav=searchWidget&module=SearchSubmit&pgtype=Homepage#/토토사이트 could be a switch that isn’t even in the network!
BPDU Guard safeguards against this disastrous possibility. If any BPDU comes in on a port that’s operating BPDU Guard, the port will probably be shut down and positioned into error disabled condition, shown about the swap as err-disabled. A port placed in err-disabled condition should be reopened manually.
BPDU Guard is off on all ports by default, and it is enabled as proven right here:
SW1(config-if)#spanning-tree bpduguard allow
It’s a smart idea to permit BPDU Guard on any port you’re running PortFast on. There’s no cost in overhead, and it does protect against the potential of a swap sending BPDUs into a port configured with PortFast – let alone the opportunity of a switch not under your Regulate becoming a root swap in your community!