Administrator Guide

OpenFlow 1647
Interaction between Flows and VLANs
The OpenFlow Controller can add flows for any VLAN ID. The VLANs for
which flows are added are created in the Dell Networking OpenFlow Hybrid
VLAN database as dynamic VLANs if they are not already configured on the
switch. Learning is enabled on the dynamic VLAN. The switch never adds
ports to OpenFlow dynamic VLANs, but instead disables ingress and egress
filtering on the ports on which the OpenFlow flows are installed. This allows
the OpenFlow traffic to be received and transmitted on those ports. The
OpenFlow flows can also be added for VLANs that are statically created in the
VLAN database. However, if the administrator removes a static VLAN with
installed flows, then the traffic for those flows may not be forwarded correctly.
The administrator should remove all flows on a static VLAN before deleting
that VLAN.
VLANs dynamically created with the flows are not deleted when the flows are
deleted. Dynamic VLANs are deleted only when the OpenFlow feature is
disabled.
If the network administrator does not wish to mix OpenFlow and non-
OpenFlow traffic on the same VLANs, then it is up to the administrator to
ensure that the OpenFlow Controller is configured such that it does not add
flows on VLANs used for non-OpenFlow traffic.
Since OpenFlow VLANs are created in hardware without any port members,
the ports on which the OpenFlow traffic enters and exits the switch must
disable egress filtering. Dell Networking OpenFlow Hybrid determines which
ports are used for OpenFlow by examining the ingress port for flows with non-
wildcard port match criteria and port numbers specified in the
OFPAT_OUTPUT action. Once ingress/egress filtering is disabled, it is re-
enabled only when the OpenFlow feature is disabled or the port is removed
from the switch. Even if a flow previously using the port is removed and there
are no other flows using the port, ingress/egress filtering remains disabled on
that port.
Normally, traffic forwarded to ports with egress filtering disabled is always
tagged. However the administrator may want to attach untagged clients to
some of the ports. If the egress VLAN is explicitly created by the network
administrator and the port is participating in the VLAN as untagged, then the
switch settings take precedence over flow rules and traffic is transmitted
untagged.