On Thu, Apr 14, 2011 at 5:04 PM, Kiran Yedavalli <
[email protected]> wrote:

>  Thanks Rajiv and Dan. Looks like we need metadata in any case for this to
> work. We initially thought of this, but our platform does not support
> metadata, so was wondering if there is a way without using metadata. Looks
> like there is none.
>

This is no reason not to use metadata. I don't believe your "software"
pipeline has to match your "hardware" pipeline. The switch can translate the
controller request to push 2 labels on 2 tables to pushing 2 labels on one
hardware table. I definitely understand that this could become non-trivial.


>
> Also, what is the reason why Action Set does not support more than one
> action of the same kind?
>

Its pretty complicated to handle multiple actions (if it was an ActionList)
because it involves "insertion" of actions in a specific order on a table
match.


>
> Thanks
> Kiran
>
>  ------------------------------
> *From:* Rajiv Ramanathan [mailto:[email protected]]
> *Sent:* Thursday, April 14, 2011 1:58 PM
> *To:* Kiran Yedavalli
> *Cc:* [email protected]
> *Subject:* Re: [openflow-discuss] Pushing 2 MPLS labels.
>
>  A couple of solutions (variations of the same theme) are:
>
> Table 0: match on dest IP, set metadata
> Table 1: match on input port, push inner label
> Table 3: match on metadata, push outer label
>
> or
>
> Table 0: match on dest IP and input port, set metadata and push inner label
> Table 1: match on metadata, push outer labe.
>
>
> On Thu, Apr 14, 2011 at 10:37 AM, Kiran Yedavalli <
> [email protected]> wrote:
>
>>  Hi,
>>
>> The problem is to push two MPLS labels onto a packet, the inner one based
>> on input port and the outer one based on destination IP address. However,
>> the spec does not allow this in any way. We looked at three options:
>>
>> Option 1. Match on input port on table 0 and push a MPLS label, next,
>> match on dest IP address in table 1 and push a MPLS label. The spec does not
>> allows this, because we cannot look at the IP address after we push a MPLS
>> label, according to the spec.
>>
>> Option 2. Match on dest IP address on table 0 and push a MPLS label, next,
>> match on input port in table 1 and push a MPLS label. But in this case,
>> according to the spec, we can only push an outmost label everytime we push.
>> This does not work for us either.
>>
>> Option 3. Accumlate all actions in the Action Set using the WriteActions
>> Instruction. This does not work either, because the Action Set cannot have
>> more than one of the same kind of action.
>>
>> Is there any other way of accomplishing this? If not, we think this is a
>> flaw in the spec that does not allow for inserting more than one label.
>>
>> Thanks
>> Kiran
>>
>>
>>
>>
>> _______________________________________________
>> openflow-discuss mailing list
>> [email protected]
>> https://mailman.stanford.edu/mailman/listinfo/openflow-discuss
>>
>>
>
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