SDN HP3800 switch broadcast fault

[ShaunWackerly]

Hi Dave,

Thanks for the confirmation, we realize this isn't ideal. From my reading of the OF1.3 spec, there is no requirement that the group action bucket contents must be unique. The only reference to uniqueness for an OF group is the group ID which is defined this way (section 5.6):

group identifier: a 32 bit unsigned integer uniquely identifying the group on the OpenFlow
switch.

The requirement that groups have a unique set of ports is likely an internal HPE design decision to ensure that OpenFlow can coordinate properly with other switch features which require port-based filtering (multicast, vlans, trunks, etc). If this becomes an inhibitor for further progress, please let us know. Thanks!

Shaun

[Dave-B]

Shaun,

Thanks for the reply. Futher to the issue of unique groups:

Changing a group number in a match action flow can cause dropped packets, which is a problem for media streams. The video can be disrupted at any pre-existing destiantions.

When I modify the ports in an exisitng group, I do not see any dropped, out-of-order or repeated packets. On my test network, adding and removing mutlicast branches using groups does not disrupt the video stream to any pre-exsiting destiantions.

Support for multicast is very important for the broadcast and media industry, for both production and delivery to viewers. Joing and leaving mutlicast streams must not cause disruption to the stream. As destiantions join/leave stream, the port groups will change. If groups are unique per switch, the match action flow would have to be changed when there is an exsiting group with the same ports.

For OF SDN to be adopted, we need multicast support. The sooner non-unique groups are supported, the better.

Dave.