22.4.7 Jumbo Frame Settings
The maximum transmission unit (MTU) in the Ethernet interface standard is 1500 octets. On the Switch, the MTU can be extended by using jumbo frames to increase the amount of data that is transmitted at one time, which improves throughput.
For a port to send or receive jumbo frames, an MTU must be set. When an MTU is set, the Switch can send or receive frames whose maximum size is the specified MTU plus the size of one VLAN tag.
Determine the port MTU value appropriate for the network and remote device. Because two VLAN tags are sometimes added (for example, when VLAN tunneling is used), add 4 to the MTU value so that frames with two VLAN tags can be sent or received.
- <Structure of this section>
(1) Configuring Per-Port MTU
- Points to note
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The example below shows how to set 8192 octets as the MTU for port 1/0/10. This setting allows you to send and receive jumbo frames of up to 8210 octets.
Command examples
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(config)# interface gigabitethernet 1/0/10
(config-if)# shutdown
(config-if)# mtu 8192
Shuts down the Ethernet interface and sets MTU of the port to 8192 octets.
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(config-if)# no shutdown
Releases the Ethernet interface from the shutdown status.
- Notes
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MTU of a port is 1500 octets when 10BASE-T is used to connect to a port (including when auto-negotiation results in an 10BASE-T).
(2) Configuring MTU for All Ports
- Points to note
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The example below shows how to set 4096 octets as the MTU for the ports of all Ethernet interfaces on the Switch. This setting allows you to send and receive jumbo frames of up to 4114 octets.
Command examples
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(config)# system mtu 4096
Sets the MTU of all ports on a switch to 4096 octets.
- Notes
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MTU of a port is 1500 octets when 10BASE-T is used to connect to a port (including when auto-negotiation results in an 10BASE-T).