[ovs-dev] Length of OXM_OF_IPV6_FLABEL and OXM_OF_MPLS_LABEL

Simon Horman horms at verge.net.au
Tue Jun 19 00:31:37 UTC 2012


On Mon, Jun 18, 2012 at 09:13:04AM -0700, Ben Pfaff wrote:
> On Mon, Jun 18, 2012 at 12:58:24PM +0900, Simon Horman wrote:
> > I am a little unsure what the correct length of the payload of
> > OXM_OF_IPV6_FLABEL and OXM_OF_MPLS_LABEL should be. The Open Flow 1.2
> > specification gives them both a length of 20 bits. Should this be
> > interpreted as 3 or 4 bytes?
> 
> openflow.h from OF1.2 says: 
> 
> /* The IPv6 Flow Label
>  *
>  * Prereqs:
>  *   OXM_OF_ETH_TYPE must match 0x86dd exactly
>  *
>  * Format: 32-bit integer with 12 most-significant bits forced to 0.
>  * Only the lower 20 bits have meaning.
>  *
>  * Masking: Maskable. */
> #define OXM_OF_IPV6_FLABEL   OXM_HEADER  (0x8000, OFPXMT_OFB_IPV6_FLABEL, 4)
> 
> /* The LABEL in the first MPLS shim header.
>  *
>  * Prereqs:
>  *   OXM_OF_ETH_TYPE must match 0x8847 or 0x8848 exactly.
>  *
>  * Format: 32-bit integer in network byte order with 12 most-significant
>  * bits forced to 0. Only the lower 20 bits have meaning.
>  *
>  * Masking: Not maskable. */
> #define OXM_OF_MPLS_LABEL  OXM_HEADER  (0x8000, OFPXMT_OFB_MPLS_LABEL, 4)
> 
> That is, each one is 4 bytes.
> 
> It doesn't seem to be easy to obtain openflow.h for OF1.2, but it's
> available in the ONF Git repository, if you have access to it.

Thanks, I believe that I do have access to that repository.



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