[ovs-discuss] Multipath routing

Ben Pfaff blp at nicira.com
Mon Mar 19 22:31:13 UTC 2012


A register, such as NXM_NX_REG0[], is one reasonable choice.

You can use "resubmit" along with a special OpenFlow table to map this
value to a destination.

On Mon, Mar 19, 2012 at 03:29:21PM -0700, Masoud Moshref Javadi wrote:
> Hum, thanks I have not read that in detail.
> OK, still I have question: We store the output of multipath
> algorithm in a field defined there, but which field should we use?
> how the value of this field relates to the routing to the destination?
> 
> On 3/19/2012 3:11 PM, Ben Pfaff wrote:
> >Did you read nicira-ext.h?
> >
> >On Mon, Mar 19, 2012 at 03:08:37PM -0700, Masoud Moshref Javadi wrote:
> >>I just want an example that fills the action part in the following rule:
> >>ovs-ofctl add-flow br0 nw_src=10.0.0.1/32,nw_dst=10.0.0.1/32,action=?
> >>
> >>The manual page says:
> >>
> >>    multipath(fields, basis, algorithm, n_links, arg, dst[start..end])
> >>
> >>    Hashes fields using basis as a universal hash parameter, then the
> >>    applies multipath link selection algorithm (with parameter arg) to
> >>    choose one of n_links output links numbered 0 through n_links minus
> >>    1, and stores the link into dst[start..end], which must be an NXM
> >>    field as described above.
> >>
> >>    Currently, fields must be either eth_src or symmetric_l4 and
> >>    algorithm must be one of modulo_n, hash_threshold, hrw, and
> >>    iter_hash. Only the iter_hash algorithm uses arg.
> >>
> >>"one of n_links output links numbered 0 through n_links minus 1",
> >>which links? Does it mean all ports? If yes, then what if it is the
> >>wrong port that does not lead to the destination? If the algorithm
> >>keeps track of the correct links that will lead to the destination
> >>what is the use of this parameter?
> >>What is dst[start..end]? would you give an example?
> >>what is *symmetric_l4?* there is no definition for it in this manual?
> >>
> >>On 3/19/2012 2:56 PM, Ben Pfaff wrote:
> >>>On Sat, Mar 17, 2012 at 10:41:05AM -0700, Masoud Moshref Javadi wrote:
> >>>>Would anyone give an example for a multipath action in openvswitch? How
> >>>>does the rule look like in ovs-ofctl command? What are the per-requisites?
> >>>It's all documented.  Which part is troublesomee?
> >>>
> >>>Thanks,
> >>>
> >>>Ben.
> 



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