Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
New Member

Can anybody solve it...

Let me tell you what I understood RSTP reg. its configuration as:”RSTP can't run on specific port/ports (b/c its a global function/command of switch) but RSTP can be stop/prevent on any specific port/ports, right, my question is How I can stop/prevent any specific port to run RSTP? (Need that command)."

To understand that why I want to do above, pls. read this my network topology…I have total 6 Catalyst 2955T-12 switches, in which 2 core switches (I will run simple RSTP on it) but…. other 4 switches are access switches that are connected to my End- workstations AS WELL AS CONNECTED TO 2 CORE SWITCHES(so thats why i want to run rstp on the ports connected to core switch and want to stop rstp on that ports connected to my workstation on these Access switches).

Can anyone solve my problem…

4 REPLIES

Re: Can anybody solve it...

Hello Shahid,

Does portfast work in this case?

"Port with the Port Fast feature enabled is moved directly to the spanning-tree forwarding state without waiting for the standard forward-time delay"

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat2950/12122ea7/scg/swstpopt.htm#wp1068987

With this you'll still have STP on the ports but they would go to FWD state faster. Just remember to also enable BPDU guard on these hosts interface to prevent loops.

Also, you can also use the spanning-tree bpdufilter enable interface configuration command to enable BPDU filtering on any port without also enabling the Port Fast feature. This command prevents the port from sending or receiving BPDUs.

Check the link for these other features as well.

HTH a bit,

if it does, please rate this post.

Vlad

New Member

Re: Can anybody solve it...

hmm... portfast will allow the switchport to roll into FORWARDING state immediately.. however.. with RSTP..portfast is already "built-in" with the concept of EDGE port.

http://www.cisco.com/en/US/customer/tech/tk389/tk621/technologies_white_paper09186a0080094cfa.shtml

Since there is no BPDU sent from your workstation back to the switch, the ports where your workstations are connected should come up in "Edge Port" status (i.e. PortFast).

You can use bpdu-filter to stop the switch from sending BPDUs toward your workstation, but that increases your risk to have a bridging loop.

New Member

Re: Can anybody solve it...

Can anyone of you tell me that command,i.e.

Command to enable bpdufilter on any specific port to prevent this port from sending/receiving BPDu's.

Waiting...

New Member

Re: Can anybody solve it...

The command documentation is here:

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat2950/12122ea7/scg/swstpopt.htm

"Understanding BPDU Filtering

The BPDU filtering feature can be globally enabled on the switch or can be enabled per interface, but the feature operates with some differences.

At the global level, you can enable BPDU filtering on Port Fast-enabled ports by using the:

spanning-tree portfast bpdufilter default

global configuration command. This command prevents ports that are in a Port Fast-operational state from sending or receiving BPDUs. The ports still send a few BPDUs at link-up before the switch begins to filter outbound BPDUs. You should globally enable BPDU filtering on a switch so that hosts connected to these ports do not receive BPDUs. If a BPDU is received on a Port Fast-enabled port, the port loses its Port Fast-operational status, and BPDU filtering is disabled.

At the interface level, you can enable BPDU filtering on any port without also enabling the Port Fast feature by using the:

spanning-tree bpdufilter enable

interface configuration command. This command prevents the port from sending or receiving BPDUs.

--------------------------------------------------------------------------------

Caution Enabling BPDU filtering on an interface is the same as disabling spanning tree on it and can result in spanning-tree loops.

--------------------------------------------------------------------------------

You can enable the BPDU filtering feature for the entire switch or for an interface. "

119
Views
2
Helpful
4
Replies
CreatePlease to create content