Brocade BigIron RX Series Configuration Guide - Manual (Page 1267)

BigIron RX Series Configuration Guide 1189
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Changing the IPv6 MTU
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Brocade does not recommend configuring a short reachable time duration, because a short
duration causes the IPv6 network devices to process the information at a greater frequency.
For example, to configure the reachable time of 40 seconds for Ethernet interface 3/1, enter the
following commands.
BigIron RX(config)# interface ethernet 3/1
BigIron RX(config-if-e100-3/1)# ipv6 nd reachable-time 40
Syntax: [no] ipv6 nd reachable-time <seconds>
For the <seconds> parameter, you can specify any numerical value. To restore the default time, use
the no form of this command.
Changing the IPv6 MTU
The IPv6 MTU is the maximum length of an IPv6 packet that can be transmitted on a particular
interface. If an IPv6 packet is longer than an MTU, the host that originated the packet fragments
the packet and transmits its contents in multiple packets that are shorter than the configured MTU.
You can configure the MTU on individual interfaces. Per RFC 2460, the minimum IPv6 MTU for any
interface is 1280 bytes.
For example, to configure the MTU on Ethernet interface 3/1 as 1280 bytes, enter the following
commands.
BigIron RX(config)# interface ethernet 3/1
BigIron RX(config-if-e100-3/1)# ipv6 mtu 1280
Syntax: [no] ipv6 mtu <bytes>
You can specify between 1280 – 1500 bytes. If a nondefault value is configured for an interface,
router advertisements include an MTU option.
You can configure IPv6 MTU for to be greater than 1500 bytes, although the default remains at
1500 bytes. The value of the MTU you can define depends on the following:
• For a physical port, the maximum value of the MTU is the equal to the maximum frame size of
the port minus 18 (Layer 2 MAC header + CRC).
• For a virtual routing interface, the maximum value of the MTU is the maximum frame size
configured for the VLAN to which it is associated, minus 18 (Layer 2 MAC header + CRC). If a
maximum frame size for a VLAN is not configured, then configure the MTU based on the
smallest maximum frame size of all the ports of the VLAN that corresponds to the virtual
routing interface, minus 18 (Layer 2 MAC header + CRC).
To define IPv6 MTU globally, enter the following command.
BigIron RX(config)#ipv6 mtu 1300
To define IPv6 MTU on an interface, enter the following command:
BigIron RX(config-if-e1000-2/1)#ipv6 mtu 1500
Syntax: ipv6 mtu <value>
NOTE
If a the size of a jumbo packet received on a port is equal to the maximum frame size – 18 (Layer
2 MAC header + CRC) and if this value is greater than the outgoing port’s IPv4/IPv6 MTU, then it will
be forwarded in the CPU.