H3C Technologies H3C S5120 Series Switches - Manual (Page 10)

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{
Hard Time—The flow entry is removed when the hard time timeout is exceeded, regardless of
whether or not it has matched packets.
• Cookie—Flow entry identifier specified by the controller.
Every flow table must support a table-miss flow entry to process table misses. The table-miss flow entry
specifies how to process packets unmatched by other flow entries in the flow table. The table-miss flow
entry wildcards all match fields (all fields omitted) and has the lowest priority 0. The table-miss flow entry
behaves in most ways like any other flow entry.
OpenFlow pipeline
The OpenFlow pipeline processing defines how packets interact with flow tables contained by a switch.
The flow tables of an OpenFlow switch are sequentially numbered, starting at 0. The packet is first
matched against flow entries of first flow table: flow table 0. A flow entry can only direct a packet to a
flow table number which is greater than its own flow table number.
When a packet matches a flow entry, the OpenFlow switch updates the action set for the packet and
passes the packet to the next flow table. In the last flow table, the OpenFlow switch executes all actions
to modify packet contents and specify the output port for packet forwarding. If the instruction set of one
of the flow tables contains an action list, the OpenFlow switch executes the actions to modify a copy of
the packet immediately in this table.
Figure 3 OpenFlow forwarding workflow
OpenFlow flow tables include the following types:
• MAC-IP—Combines the MAC address table and FIB table.
A MAC-IP flow table provides the following match fields:
{
Destination MAC address
{
VLAN
{
Destination IP address
A MAC-IP flow table provides the following actions:
{
Modifying the destination MAC address
{
Modifying the source MAC address
{
Modifying the VLAN
{
Specifying the output port
• Extensibility—Provides more matching fields and actions than a MAC-IP flow table does.
Group table
The ability for a flow entry to point to a group enables OpenFlow to represent additional methods of
forwarding. A group table consists of group entries.