Brocade Multi-Service IronWare Switching Configuration Guide (Supporting R05.6.00) - Manual (Page 773)

Multi-Service IronWare Switching Configuration Guide 743
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Configuring IP parameters
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3. If neither an IPv4 Interface MTU value or an IPv4 Global MTU value are configured, the default
IPv4 MTU value of 1500 will be used.
Globally changing the IP MTU
To globally enable jumbo support on all IP interfaces, enter commands such as the following.
Brocade(config)# ip global-mtu 5000
Brocade(config)# write memory
Syntax: [no] ip global-mtu bytes
The bytes parameter specifies the maximum IP packet size to be forwarded on a port. You may
enter any number within the range of 576 – 9198. However, this value must be 18 bytes less than
the value of the global maximum frame size.
NOTE
The global IP MTU change does not get applied to IP tunnel interfaces such as GRE interface. The
MTU for these interfaces has to be changed on interface level.
Changing the maximum transmission unit on an individual interface
By default, the maximum IP MTU sizes are as follows:
• 1500 bytes – The maximum for Ethernet II encapsulation
NOTE
The IP MTU configured at the IP interface level takes precedence over the IP MTU configured at the
global level for that IP interface.
To change the IP MTU for interface 1/5 to 1000, enter the following commands.
Brocade(config)# int e 1/5
Brocade(config-if-e10000-5)# ip mtu 1000
Syntax: [no] ip mtu bytes
The bytes variable specifies the IP MTU. However, the value of IP MTU on an interface cannot
exceed the configured value default-max-frame-size, minus 18 bytes. The default IP MTU for
Ethernet II packets is 1500.
If the interface is part of a VLAN, then ensure that you change the IP MTU only at the VE interface
and not at the physical port. To change the IP MTU at the VE interface, enter the following
commands:
Brocade(config)# int ve 103
Brocade(config-vif-103)# ip mtu 1000
NOTE
All member ports of a VLAN will have the same IP MTU value as the VE interface.