The OpenFlow agent
requires the Cisco Nexus device to be configured with OpenFlow specific
commands in order to support topology discovery and the installation of flows.
The Cisco Nexus device works in a hybrid mode so that the default commands from
the startup-config file are executed upon boot up. This might create an
undesirable effect and therefore must be changed.
![](https://www.cisco.com/content/dam/en/us/td/i/templates/note.gif)
Note
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If you change or
negate these required commands, it can lead to unpredictable system behavior.
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VLAN
Creation
The following
command is used to create the necessary VLANs in an OpenFlow-controller switch.
This command creates the OpenFlow specific VLANs in the VLAN database.
vlan x[-y]
Even with the
hybrid-Ships-In-Night mode of operation, we recommend that you segregate the VLANs among
the OpenFlow-controlled ports and the regular ports. You should take caution in
ensuring that the VLANs are not shared among the OpenFlow and non-OpenFlow
ports in order to prevent traffic leaks.
Interface Level
Configurations
To make the
interfaces connected to other switches receive spanned traffic, the interface
is connected to the analyzer and configured to support OpenFlow. The interface ethernet command changes the parser to
the interface submode. Before entering the
mode openflow
command which enables OpenFlow support on the interface, the following commands
are required:
In order for the
strip-vlan functionality to work on the Cisco Nexus device, the trunk port must
be configured with the native VLAN.
Cisco One controllers can perform topology discovery of OpenFlow enabled ports. To allow topology discovery on trunk ports,
the native VLANs must be configured on trunk ports
switchport trunk native vlan z
When an interface is
added to the OpenFlow logical switch, the following commands are applied to the
interface implicitly:
Template Based
TCAM Carving for OpenFlow
The Cisco Nexus
device supports template-based TCAM carving. To configure OpenFlow on the device, you must make a number of changes to
the TCAM carving regions using the template based TCAM carving commands.
To configure OpenFlow on the switch you must increase the default size of the Sup region to 256 using the template based TCAM
carving commands, as shown in this example:
switch(config)# hardware profile tcam resource template openflow
switch(config-tcam-templ)# sup 256
switch(config)# hardware profile tcam resource service-template openflow
To support higher scale numbers for OpenFlow policies, the IFACL-region of the TCAM must be recarved accordingly. To apply
TCAM
carving for a maximum flow scale, enter the following commands:
switch(config)# hardware profile tcam resource template openflow
switch(config-tcam-templ)# vacl 64
switch(config-tcam-templ)# ifacl 3520
switch(config-tcam-templ)# qos 128
switch(config-tcam-templ)# rbacl 64
switch(config-tcam-templ)# span 64
switch(config)# hardware profile tcam resource service-template openflow
Enter the following
command to verify the TCAM carving:
show hardware profile tcam
resource template
tmplt-name
![](https://www.cisco.com/content/dam/en/us/td/i/templates/note.gif)
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Configuring TCAM
carving requires that the Cisco Nexus device be reloaded.
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