Setup Guide

• When you insert a QSA into a 40 Gigabit port, you can use only the rst 10 Gigabit port in the fan-out mode to plug-in SFP or SFP+
cables. The remaining three 10 Gigabit ports are perceived to be in Link Down state and are unusable.
• You cannot use QSFP Optical cables on the same port where QSA is used.
• When you remove the QSA module alone from a 40 Gigabit port, without connecting any SFP or SFP+ cables; Dell Networking OS
does not generate any event. However, when you remove a QSA module that has SFP or SFP+ optical cables plugged in, Dell
Networking OS generates an SFP or SFP+ Removed event.
Example Scenarios
Consider the following scenarios:
• QSFP port 0 is connected to a QSA with SFP+ optical cables plugged in.
• QSFP port 4 is connected to a QSA with SFP optical cables plugged in.
• QSFP port 8 in fanned-out mode is plugged in with QSFP optical cables.
• QSFP port 12 in 40 G mode is plugged in with QSFP optical cables.
For these congurations, the following examples show the command output that the show interfaces tengigbitethernet
transceiver, show interfaces tengigbitethernet, and show inventory media commands displays:
NOTE: In the following show interfaces tengigbitethernet commands, the ports 1,2, and 3 are inactive and no physical
SFP or SFP+ connection actually exists on these ports. However, Dell Networking OS still perceives these ports as valid and the
output shows that pluggable media (optical cables) is inserted into these ports. This is a software limitation for this release.
Link Dampening
Interface state changes occur when interfaces are administratively brought up or down or if an interface state changes.
Every time an interface changes a state or aps, routing protocols are notied of the status of the routes that are aected by the change in
state. These protocols go through the momentous task of re-converging. Flapping; therefore, puts the status of entire network at risk of
transient loops and black holes. Dampening limits the notication of status to the routing protocols. Link dampening minimizes the risk
created by apping by imposing a penalty (1024) for each interface ap and decaying the penalty exponentially based on the half-time.
When the accumulated penalty exceeds a certain threshold (suppress threshold), the interface is put in an Error-Disabled state and for all
practical purposes of routing, the interface is deemed to be “down.” After the interface becomes stable and the penalty decays below a
certain threshold (reuse threshold), the interface comes up again and the routing protocols re-converge.
You congure link dampening using the dampening [[[[half-life] [reuse-threshold]] [suppress-threshold]]
[
max-suppress-time]] command on the interface.
Following is the detailed explanation of interface state change events:
• suppress-threshold— The suppress threshold is a value that triggers a apping interface to dampen. The system adds penalty
when the interface state goes up and down. When the accumulated penalty reaches the default or congured suppress threshold, the
interface state changes to Error-Disabled state. The range of suppress threshold is from 1 to 20000. The default is
2500.
• half-life— The accumulated penalty decays exponentially based on the half-life period. The accumulated penalty decreases half
after each half-life period. The range of half-life is from 1 to 30 seconds. The default is 5 seconds.
• reuse-threshold— After exponential decay, the penalty reaches the default or congured reuse threshold. The interface is
unsuppressed and the state changes to “up”. The range of reuse threshold is from 1 to 20000. The default is
750.
• max-suppress-time— The maximum amount of time during which the interface remain suppressed. The range is from 1 to 86400.
The default is 20 seconds or four times the default half-life period (5 seconds).
Interfaces
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