Enabling forwarding of jumbo frames, Enabling loopback detection on an ethernet port – H3C Technologies H3C S5120 Series Switches User Manual

Page 90

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Enabling Forwarding of Jumbo Frames

Due to tremendous amount of traffic occurring on an Ethernet port, it is likely that some frames greater

than the standard Ethernet frame size are received. Such frames (called jumbo frames) will be dropped.

With forwarding of jumbo frames enabled, the system does not drop all the jumbo frames. Instead, it

continues to process jumbo frames with a size greater than the standard Ethernet frame size and yet

within the specified parameter range.

In global configuration mode (system view), you can set the length of jumbo frames that can pass

through the Ethernet port.

Follow these steps to enable the forwarding of jumbo frames:

To do…

Use the command…

Remarks

Enter system view

system-view

Enable the forwarding of jumbo
frames

jumboframe enable

Optional.

By default, the device
allows jumbo frames with
the length of 10240 bytes
to pass through all Layer 2
Ethernet ports.

Enabling Loopback Detection on an Ethernet Port

If an interface receives a packet that it sent out, a loop occurs. Loops may cause broadcast storms. The

purpose of loopback detection is to detect loops on an interface. When loopback detection is enabled

on an Ethernet port, the device periodically checks for loops on the interface. If a loop is detected on the

interface, the device operates on the port according to the pre-configured loopback detection actions,

and sends a trap message to the terminal.

z

When a loop is detected on an access port, the device puts the port in control mode. In this mode,

inbound packets on the port are all discarded, while outbound packets on the port are forwarded

normally. Meanwhile, the device sends trap messages to the terminal, and deletes the

corresponding MAC address forwarding entry.

z

When a loop is detected on a trunk port or a hybrid port, the device sends a trap message to the

terminal. If loopback detection control is enabled on the port, the device places the port in control

mode and discards all inbound packets on the port while normally forwarding outbound packets on

it. Meanwhile, the device sends trap messages to the terminal, and deletes the corresponding MAC

address forwarding entry.

.Follow these steps to configure loopback detection:

To do…

Use the command…

Remarks

Enter system view

system-view

Enable global loopback
detection

loopback-detection enable

Required

Disabled by default

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