No, select buckets don't use mod-n to select a bucket. Instead, for each live bucket, OVS hashes flow data with the bucket ID and multiplies by the bucket weight to obtain a "score", and then selects the bucket with the highest score.
On Mon, Apr 24, 2017 at 12:27:16AM +0530, Ahmed Khan wrote: > Hi ben, > Let me rephrase. > > Does hashing involve mod on number of buckets in a group ? If a new bucket > is added/deleted in a group, would it result in different hash value and > hence a selection of different bucket for the same 5 tuple ? > > Also, how many buckets per group does ovs support ? And how many group > tables are supported ? > > Thanks. > > On 22 Apr 2017 02:34, "Ben Pfaff" <[email protected]> wrote: > > > On Thu, Apr 20, 2017 at 04:12:20PM +0530, Ahmed Khan wrote: > > > I understand that, > > > > > > *"""* > > > > > > *Open vSwitch 2.4 and later by default hashes the source and > > > **destination Ethernet address, VLAN ID, Ethernet type, IPv4/v6 > > > **source and destination address and protocol, and for TCP and SCTP > > > **only, the source and destination ports. The hash is "symmetric", > > > **meaning that exchanging source and destination addresses does not > > > **change the bucket selection.* > > > > > > *"""* > > > > > > *How does bucket size impact selection ? If entries are added/deleted > > > to/from bucket, then for the same 5tuple is it rehashed and new entry > > > could get selected ?* > > > > OpenFlow groups do contain buckets, but buckets do not have entries. > > Therefore, entries cannot be added or deleted within buckets, so I don't > > understand the question. Can you rephrase it? > > > > Thanks, > > > > Ben. > > _______________________________________________ discuss mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
