[ovs-discuss] STP Support

[Luca Prete]

it can be enabled with

*ovs-vsctl -- clear Bridge br0 sflow*


	

*802.1D Spanning Tree Protocol (STP)*


	

Configure bridge *br0* to participate in an 802.1D spanning tree:


	

*ovs-vsctl set Bridge br0 stp_enable=true*


	

Set the bridge priority of *br0* to 0x7800:


	

*ovs-vsctl set Bridge br0 other_config:stp-priority=0x7800*


	

Set the path cost of port *eth0* to 10:


	

*ovs-vsctl set Port eth0 other_config:stp-path-cost=10*


	

Deconfigure STP from above:


	

*ovs-vsctl clear Bridge br0 stp_enable*


In 1.0 specs there's written:
*Spanning Tree
*OpenFlow switches may optionally support 802.1D Spanning Tree Protocol.
Those switches that do support it are expected to process all 802.1D packets
locally before performing
ow lookup. A switch that implements STP must
set the OFPC_STP bit in the 'capabilities' eld of its 
OFPT_FEATURES_REPLY message.
A switch that implements STP must make it available on all of its physical
ports, but it need not implement it on virtual ports (e.g. OFPP_LOCAL).
Port status, as specied by the spanning tree protocol, is then used to 
limit
packets forwarded to the OFP_FLOOD port to only those ports along the 
spanning
tree. Port changes as a result of the spanning tree are sent to the 
controller
via port-update messages. Note that forward actions that specify the 
outgoing
port or OFP_ALL ignore the port status set by the spanning tree 
protocol. Packets
received on ports that are disabled by spanning tree must follow the 
normal flow table processing path.
Switches that do not support 802.1D spanning tree must allow the 
controller to
specify the port status for packet flooding through the port-mod messages.

About Beacon Controller, "for switches that support STP, they can return 
the OFPC_STP bit in the capabilities field of the features reply 
message. This will then limit the ports that the flow mod action flood 
will send to, and Beacon will automatically take advantage of this for 
flooding".

Otherwise everything should be done manualy on the controller.


LP

Il 23/04/2012 18:55, Ben Pfaff ha scritto:
> On Mon, Apr 23, 2012 at 09:50:20AM -0700, Justin Pettit wrote:
>> On Apr 23, 2012, at 9:22 AM, Ben Pfaff wrote:
>>
>>> On Mon, Apr 23, 2012 at 11:18:07AM +0200, Luca Prete wrote:
>>>> Does anyone know if OVS return the OFPC_STP bit in the capabilities
>>>> field when STP is activated?
>>> I think that it doesn't.  Perhaps it should.
>> You're right; this looks like an oversight.  I'll look into it.  I
>> think we should set that bit whenever a DPIF-based datapath is used,
>> not just when STP is enabled, though.
> I don't recall how OVS enables or disables STP.  If it can't be
> enabled through OpenFlow, then it might not make sense to set
> OFPC_STP.  If it can, then of course it does make sense.
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