Hi Zoltan, Thanks alot. You clarify the things in really good manner. It helps me alot. Thanks again.
Regards 2011/4/8 Zoltán Lajos Kis <[email protected]> > Hi, > > > 3. What is the difference between 'Action list' & 'Action set'? > An 'Action set' contains a set of actions, i.e. only one action of a type > can exist within the set. The order the actions were inserted into the set > is irrelevant, their execution order is defined by the spec (p. 12.). > An 'Action list' on the other hand can contain any number of the same type > of action, and the execution order of these actions is defined by their > order in the list. > > Note that in the structures defined by the spec., both sets and lists are > stored as lists (i.e. actions one after the other). But their interpretation > should differ in the datapath according to the spec. > > > 2. ... How action set can be associated with each packet. > > When a packet enters the pipeline, you associate an action set with it, > which is at that time empty. When the packet encounters a write instruction, > actions of that instruction are put into the action set of the packet. If > there are actions of the same type in both the write instruction, and in the > packet's action set, only those of the instruction's are kept. If a clear > instruction is executed, the packet's action set is emptied. (If a flow > entry has both clear and write instructions, clear is always executed > first.) > When the packet exits the pipeline, if it has some actions in its action > set, they will be executed in the order defined by the spec (p. 12.). > > 1> My question is that is only the Apply-Actions instruction and the > Packet-out message include an action list. What about the 'Clear-action' and > Write-action instructions? If these later instructions does not contain any > action list, then which action-list is cleared by 'Clear-action'. Where that > action list is stored. > As now it should be clearer, the Apply instruction and packet-out message > contains an action list in the sense that those actions will be executed in > the order they appear in the list, and also that multiple types of the same > action is accepted. > On the other hand, Write instruction contains a set, which is only appended > to the packet's action set. Clear action does not store actions. > > Regards, > Zoltan. > > > ________________________________ > From: [email protected] [ > [email protected]] On Behalf Of Tahir Rauf [ > [email protected]] > Sent: Friday, April 08, 2011 2:48 PM > To: [email protected] > Subject: [openflow-discuss] Ambiguities about Instructions and Actions > > Hi, > > I have some ambiguities in understanding the OpenFlowSpec-v1.1.0 document. > Can you please help me in clarifying the things > 1. In section 4.6, the document writes > > "Applies the speci c action(s) immediately, without any change to the > Action Set. This > instruction may be used to modify the packet between two tables or to > execute > multiple actions of the same type. The actions are speci ed as an > action list (see 4.8)" > > 2. Then it writes in section 4.8 that > > "The Apply-Actions instruction and the Packet-out message include an > action list" > > Up till now all seems right. I am considering that action list is stored > along with Apply-Actions instruction in flow table. And whenever a flow > matches, the switch applies all actions associated with the Apply-Actions > instruction. Similarly, in case of Packet-out message, the controller send > the action list along with message. > > Ambiguities: > 1. My question is that is only the Apply-Actions instruction and the > Packet-out message include an action list. What about the 'Clear-action' and > Write-action instructions? If these later > instructions does not contain any action list, then which action-list > is cleared by 'Clear-action'. Where that action list is stored. > > 2. In section 4.7, the document says that > "An action set is associated with each packet" > What does it mean? How action set can be associated with each packet. > > 3. What is the difference between 'Action list' & 'Action set'? > > > Regards > -- Tahir Rauf High Performance Computing Lab http://hpc.seecs.edu.pk/~tahir.rauf/ SEECS-NUST,
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