Cisco CCNP / 먹튀검증 BCMSN Examination Tutorial: Configuring PortFast And BPDU Guard
With your CCNA experiments, you learned about PortFast and The difficulty it could cause if configured on the incorrect port! Suited only for switch http://query.nytimes.com/search/sitesearch/?action=click&contentCollection®ion=TopBar&WT.nav=searchWidget&module=SearchSubmit&pgtype=Homepage#/토토사이트 ports connected on to an individual host, PortFast permits a port managing STP to go directly from blocking to forwarding manner.
A Cisco router gives you a warning after you configure PortFast:
SW1(config)#int quick 0/five
SW1(config-if)#spanning-tree portfast
%Warning: portfast should really only be enabled on ports linked to a
single host. Connecting hubs, concentrators, switches, bridges, and so on…
to this interface when portfast is enabled, can cause temporary
bridging loops. Use with CAUTION
%Portfast continues to be configured on FastEthernet0/five but will only
have impact once the interface is within a non-trunking manner.
SW1(config-if)#
Don't just will the swap alert you about the proper use of PortFast, but you will need to place the port into entry method ahead of PortFast will get outcome.
Now, you’d believe that would be sufficient of the warning, suitable? But there is a chance – just a chance – that someone will probably take care of to attach a swap into a port working Portfast. That might bring about two main complications, the primary being the development of a switching loop. Don't forget, The rationale We have now listening and Discovering modes is to help protect against switching loops. The next issue is the fact that there can be a fresh root bridge elected – and it may be a swap that isn’t even in your network!
BPDU Guard protects towards this disastrous risk. If any BPDU comes in with a port that’s operating BPDU Guard, the port will be shut down and put into error disabled state, proven on the switch as err-disabled. A port placed in err-disabled point out need to be reopened manually.
BPDU Guard is off on all ports by default, and is particularly enabled as demonstrated below:
SW1(config-if)#spanning-tree bpduguard empower
It’s a good idea to enable BPDU Guard on any port you’re running PortFast on. There’s no cost in overhead, and it does avert the possibility of a change sending BPDUs right into a port configured with PortFast – in addition to the potential of a change not below your Handle getting a root change on your community!