Filter
Top Products
C H A P T E R 6 Configuring Ports
83
IP Fragmentation with Jumbo frames
To set the MTU size
greater than 1500, all
ports in the VLAN must be
jumbo-frame enabled.
If an IP packet originates in a local network that allows large
packets and that packet traverses a network that limits packets to a
smaller size, the packet is fragmented instead of discarded. This is
designed for use in conjunction with jumbo frame support.
Frames that are fragmented are not processed at wire-speed within
the switch fabric.
Also note that jumbo frame to jumbo frame fragmentation is not
supported – only jumbo frame to normal frame fragmentation is
currently supported.
To configure VLANs for IP fragmentation:
1. Enable jumbo frames on the incoming port
2. Add the port to a VLAN
3. Assign an IP address to the VLAN
4. Enable IP forwarding on the VLAN
5. Set the MTU size using the following new command:
configure ip-mtu <size> vlan <vlan name>
The ip-mtu value can be 1500 or 9216, with 1500 the default. If
you enter a value other than 1500, the switch will recognize that
value as 9216.
IP Fragmentation within a VLAN
The routing switch also supports IP fragmentation within a VLAN.
This feature does not require you to configure the MTU size. To use
IP fragmentation within a VLAN:
1. Enable jumbo frames on the incoming port
2. Add the port to a VLAN
3. Assign an IP address to the VLAN
4. Enable IP forwarding on the VLAN
If you leave the default MTU (maximum transmission unit) size
when you enable jumbo-frame support on a port in the VLAN, you
will receive a warning that the VLAN IP-MTU size is not set at
maximum jumbo frame size. You can ignore this warning if you