H3C Technologies H3C S5120 Series Switches - Manual (Page 90)

1-9
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