When applying a group action to a frame, the action set is executed first

[YuvalAdler]

Hi,

I've noticed a behavior which I think is not according to the spec, wanted to hear your opinion:

Let's say I have the following CLI commands:

group-mod cmd=add,type=all,group=1 weight=0,port=any,group=any output=2
flow-mod cmd=add,table=0 eth_type=0x0800 write:push_vlan=0x8100,output=3 apply:group=1

For the above configuration, I would assume that a matching frame will be sent to port 2 without the vlan header.
Moreover, when reversing the "write" and "apply" command as:

flow-mod cmd=add,table=0 eth_type=0x0800 apply:group=1 write:push_vlan=0x8100,output=3

The vlan header is not pushed to the frame exiting from port 2.

According to the spec ('Instructions' chapter):
"The instructions of the set execute in the order specified by this above list"
The 'above' list indicates that "apply" should be executed first.

The fix should be easy if I'm not mistaken, just changing action_set_clone() function to only init the list without copying it.

Thanks.

[ZoltanLajosKis]

You are right, this is a bug according to OpenFlow 1.3 (but not for previous versions).

In OF 1.1. and OF 1.2 the only instruction constraints were that Goto is the last, and Clear is done before Write. The relation of Write and Apply was unspecified. When OF 1.3 introduced the Meter instruction, defining the minimum set of constraints become unfeasible, so a proper ordering was defined instead. (Which "accidentally" also affects the Write to Apply relation).

[ederlf]

Yes, we noticed the problem this last week, while creating some tests for
oftest.

Also, there are problems with goto not being the last instructions
executed. The solution is to check the execution order on execute_entry in
udatapath/pipeline.c. (There ate some checks already,)
Maybe it's better to order the instructions while unpacking them, ensuring
a proper order execution.

On Sun, Jan 27, 2013 at 12:16 PM, Zoltán Lajos Kis <notifications@github.com

wrote:

You are right, this is a bug according to OpenFlow 1.3 (but not for
previous versions).

In OF 1.1. and OF 1.2 the only instruction constraints were that Goto is
the last, and Clear is done before Write. The relation of Write and Apply
was unspecified. When OF 1.3 introduced the Meter instruction, defining the
minimum set of constraints become unfeasible, so a proper ordering was
defined instead. (Which "accidentally" also affects the Write to Apply
relation).

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Converged Networks Business Unit
CPqD - Center for Research and Development in Telecommunications
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[ederlf]

I pushed a fix, where the instruction set is ordered to execute in the specified order. I did some tests and it seems to be working fine.

[YuvalAdler]

I opened a new pull request due to a crash on my PC.