Enabling Forwarding Of Jumbo Frames; Enabling Loopback Detection On An Ethernet Port - 3Com 4500G Family Configuration Manual

To do...
Set the interval for collecting
statistics on the Ethernet port

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 port configuration mode (Ethernet port view/port-group view), you can enable jumbo frames that can
pass through the Ethernet port.
If you execute the command in Ethernet port view, the configurations take effect only on the current
port.
If you execute the command in port-group view, the configurations take effect on all ports in the port
group.
Follow these steps to enable the forwarding of jumbo frames:
To do...
Enter system view
Enable the
forwarding of
jumbo
frames

Enabling Loopback Detection on an Ethernet Port

If a port 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 a port.
When loopback detection is enabled on an Ethernet port, the device periodically checks whether the
ports have any external loopback. If it detects a loopback on a port, the device will set that port to be
under loopback detection mode.
If loops are detected on an access port, the port will be blocked. Meanwhile, trap messages will be
sent to the terminal, and the corresponding MAC address forwarding entries will be removed.
If loops are detected on a trunk port or a hybrid port, trap messages are sent to the terminal. If the
loopback detection control function is also enabled on the port, the port will be blocked, trap
messages will be sent to the terminal, and the corresponding MAC address forwarding entries will
be removed.
Follow these steps to configure loopback detection:
flow-interval interval
system-view
port-group manual
In port-group
port-group-name
view
jumboframe enable
interface interface-type
In Ethernet port
interface-number
view
jumboframe enable
Use the command...
Use the command...
1-7
Remarks
Optional
By default, the interval for
collecting port statistics is 300
seconds.
Remarks
—
Use any command.
By default, the device
allows jumbo frames with
the length of 1.522 bytes to
pass through all Layer 2
Ethernet ports.