Link Level Policies
You can configure link level policies, which are a type of access policy. A link level policy includes the physical layer (Layer 1) interface configurations, such as auto-negotiation, port speed, and link debounce.
Electromagnetic Interference Retrain
In the 5.2(4) and later releases, the electromagnetic interference (EMI) retrain feature filters any noise on a link due to electromagnetic interference, and retrains the link to avoid a link flap. Enable EMI retrain if your data center environment has a lot of EMI noise.
You can enable EMI retrain when you configure a link level policy by choosing enable for the EMI Retrain property. This feature is supported only with the Cisco N9K-C93108TC-EX and N9K-C93108TC-FX leaf switches using copper cables.
Configuring a Link Level Policy Using the GUI
Procedure
Step 1 |
On the menu bar, choose . |
Step 2 |
In the Navigation pane, choose . |
Step 3 |
Right-click Link Level and choose Create Link Level Policy. |
Step 4 |
In the Create Link Level Policy dialog, fill out the fields as appropriate for your desired configuration. For Speed, we recommend that you choose inherit, which is the default value. With this value, the Cisco APIC determines the speed based on the transceiver that is inserted into a switch. See the tooltips for more information about the fields. |
Step 5 |
Click Submit. |
Port Bring-up Delay
When you configure a link level policy, you can set the Port bring-up delay (milliseconds) parameter, which specifies a time in milliseconds that the decision feedback equalizer (DFE) tuning is delayed when a port is coming up. The delay is used to help avoid CRC errors during link bringup when using some third-party adapters. You should set the delay only as required; in most cases, you do not need to set a delay.
Note |
The Port bring-up delay (milliseconds) parameter is not honored on fabric extender (FEX) ports. |
Link Debounce Interval
A link level policy applies to the fabric interfaces (leaf switch uplink ports and spine switch ports) at the link level and you use this policy where there might be link noise or transient flaps. In this policy, you can configure the link debounce interval, which specifies a wait time for the fabric interfaces when there is a flap in the link. After the interval passes, Cisco Application Centric Infrastructure (ACI) checks the link status again to re-confirm the event. If the link is okay at this time, then the interfaces will remain up.
Set the interval in a link level policy using the Link debounce interval (msec) field in the Cisco Application Policy Infrastructure Controller (APIC) GUI or the [no] link debounce time <time> CLI command. The default debounce interval is 0 ms. We recommend a value of 100 ms, but you should choose a value that is appropriate to your fabric.