Interacting With Baby Giants - Cisco Catalyst 4500 Series Configuration Manual

Configuring Optional Interface Features

Interacting with Baby Giants

The baby giants feature, introduced in Cisco IOS Release 12.1(12c)EW, uses the global command
system mtu size to set the global baby giant MTU. This feature also allows certain interfaces to support
Ethernet payload size of up to 1552 bytes.
Both the system mtu command and the per-interface mtu command can operate on interfaces that can
support jumbo frames, but the per-interface mtu command takes precedence.
For example, before setting the per-interface MTU for interface gi1/1, you enter the system mtu 1550
command to change the MTU for gi1/1 to 1550 bytes. You enter the per-interface mtu command to
change the MTU for gi1/1 to 9198 bytes. If you change the baby giant MTU to 1540 bytes with the
command system mtu 1540, the MTU for gi1/1 remains unchanged at 9198 bytes.
Configuring the Port Debounce Timer
You can only configure port debounce on 10-Gigabit Ethernet ports.
Note
The port debounce timer suppresses notification of short link-down events. Link-down events that are
shorter than the port debounce timer are not notified to Layer 2 or Layer 3 protocols, decreasing traffic
loss due to network reconfiguration. You can configure the port debounce timer separately on each LAN
port.
Enabling the port debounce timer causes a delay in link down detections, resulting in loss of traffic
Caution
during the debouncing period. This situation might affect the convergence and reconvergence of some
Layer 2 and Layer 3 protocols.
To configure the debounce timer on a port, perform this task:
Command
Step 1
Switch(config)# interface tengigabitethernet
slot/port
Step 2
Switch(config-if)# link debounce [time
debounce_time]
Switch(config-if)# no link debounce
Step 3
Switch# show interfaces debounce
Note The default time is 10ms for E-series supervisor engines and line cards.
When configuring the debounce timer on a port, you can increase the port debounce timer value between
10 milliseconds and 5000 milliseconds on the 10-Gigabit Ethernet ports.
This example shows how to enable the port debounce timer on 10-Gigabit Ethernet port 2/1 and to accept
the default value (10 ms):
Switch# config terminal
Enter configuration commands, one per line.
Software Configuration Guide—Release IOS XE 3.3.0SG and IOS 15.1(1)SG
7-28
Purpose
Selects the port to configure.
Configures the debounce timer.
By default, debounce is disabled.
Reverts to the default setting.
Verifies the configuration.
End with CNTL/Z.
Chapter 7 Configuring Interfaces
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