Dell Force10 E300, Configuration Manual

Page: 446 / 1262

446 | Interfaces
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To test the condition of cables on 10/100/1000 BASE-T modules, use the
tdr-cable-test
command:
Link Debounce Timer
Link Debounce Timer is supported on platform
e
This feature is supported on E-Series ExaScale
e
x
with FTOS 8.2.0.1 and later
The Link Debounce Timer feature isolates upper layer protocols on Ethernet switches and routers from
very short-term, possibly repetitive interface flaps often caused by network jitter on the DWDM equipment
connecting the switch and other devices on a SONET ring. The Link Debounce Timer delays link change
notifications, thus decreasing traffic loss due to network configuration. All interfaces have a built-in timer
to manage traffic. This feature extends the time allowed by the upper layers.
The SONET ring has its own restore time whenever there is a failure. During this time, however,
the Ethernet interface connected to the switch will flap. Link Debounce Timer instructs the
Ethernet switch to delay the notification of the link change to the upper layers. If the link state
changes again within this period, no notification goes to the upper layers, so that the switch
remains unaware of the change.
Important Points to Remember about Link Debounce Timer
• Link Debounce Timer is configurable on physical ports only.
• Only 1G fiber, 10/100/1000 copper, 10G fiber, 10G copper are supported.
• This feature is not supported on management interfaces or SONET interfaces.
• Link Debounce takes effect only when the operational state of the port is up.
• Link Debounce is supported on interfaces that also have link dampening configured.
• Unlike link dampening, link debounce timer does not notify other protocols.
Step Command Syntax Command Mode Usage
1
tdr-cable-test gigabitethernet
<slot>/
<port>
EXEC Privilege To test for cable faults on the GigabitEthernet
cable.
• Between two ports, the user must not start
the test on both ends of the cable.
• The user must enable the interface before
starting the test.
• The port should be enabled to run the test
or the test prints an error message.
2
show tdr gigabitethernet
<slot>/
<port>
EXEC Privilege Displays TDR test results.
Note: Enabling the link debounce timer causes link up and link down detections to be delayed, resulting in
traffic being blackholed during the debouncing period. This situation might affect the convergence and
reconvergence of some Layer 2 and Layer 3 protocols.