Configuring Static PMTU
Context
Generally, PMTU is dynamically negotiated according to the IPv6 MTU value of an interface. In special situations, to protect devices on the network and avoid attacks from large-sized packets, you can manually configure the PMTU to a specified destination node to control the maximum length of packets forwarded from the device to the destination node.
When the PMTU from the device to a specified destination node is set, the IPv6 MTU values for interfaces on all intermediate devices cannot be smaller than the configured PMTU value. Otherwise, packets are discarded.
Procedure
- Run system-view
The system view is displayed.
- (Optional) Configure the IPv6 MTU for an interface.
Run interface interface-type interface-number
The specified interface view is displayed.
Run ipv6 mtu mtu
The MTU of IPv6 packets on an interface is set.
By default, the MTU of IPv6 packets on an interface is 1500 bytes. The default MTU of IPv6 packets on IPv6 over IPv4 tunnel interfaces is 1480 bytes on the AR611W, AR611W-LTE4CN, AR617VW, AR617VW-LTE4, and AR617VW-LTE4EA.
Run quit
Return to the system view.
- Run ipv6 pathmtu ipv6-address [ vpn-instance vpn-instance-name ] [ path-mtu ]
The PMTU for a specified IPv6 address is set.
By default, the PMTU is not set.
If the parameter path-mtu is not specified, the PMTU for a specified IPv6 address is 1500 bytes.