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Verifying the configuration
After the configurations are completed, if you ping the subnet-directed broadcast address 2.2.2.255
on the host, VLAN-interface 2 of Switch B can receive the ping packets. If you delete the
ip
forward-broadcast
configuration on any switch, the interface cannot receive the ping packets.
Setting the MTU of IPv4 packets sent over an
interface
About setting the MTU of IPv4 packets sent over an interface
When a packet exceeds the MTU of IPv4 packets sent over an interface, the device processes the
packet in one of the following ways:
• If the packet disallows fragmentation, the device discards it.
• If the packet allows fragmentation, the device fragments it and forwards the fragments.
Fragmentation and reassembling consume system resources, so set the MTU based on the network
environment to avoid fragmentation.
Procedure
1. Enter system view.
system-view
2. Enter interface view.
interface interface-type interface-number
3. Set the MTU of IPv4 packets sent over the interface.
ip mtu mtu-size
By default, the MTU of IPv4 packets sent over an interface is not set.
Enabling sending ICMP error messages
About sending ICMP error messages
ICMP messages are used by network layer and transport layer protocols to communicate updates
and errors with other devices, facilitating network management.
Sending excessive ICMP messages increases network traffic. The device performance degrades if it
receives a lot of malicious ICMP messages that cause it to respond with ICMP error messages. To
prevent such problems, the sending of ICMP error messages is disabled by default. You can enable
sending ICMP error messages of different types as needed.
ICMP error messages include redirect messages, time exceeded messages, and destination
unreachable messages.
Enabling sending ICMP redirect messages
About ICMP redirect messages
A host that has only one default route sends all packets to the default gateway. The default gateway
sends an ICMP redirect message to inform the host of a correct next hop by following these rules:
• The receiving and sending interfaces are the same.
• The selected route is not created or modified by any ICMP redirect messages.
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