78 CHAPTER 4: NETWORK PROTOCOL OPERATION
operation, you may have to use the following commands to prevent the
corresponding packets from being sent to the CPU.
Perform the following configuration in system view.
By default, redirection packets and route unreachable packets are not sent to CPU,
while TTL timeout packets are sent to CPU.
Configuring L3
Broadcast Forwarding
Broadcast packets include full-net broadcast packets and direct-connected
broadcast packets. The destination IP address of a full-net broadcast packet is all
ones (255.255.255.255) or all zeros. A direct-connected broadcast packet is a
packet whose destination IP address is the network broadcast address of a subnet,
but the source IP address is not in the subnet segment. When a switch forwards a
packet, it cannot tell whether the packet is a broadcast packet unless the switch is
connected with the subnet.
If a broadcast packet reaches the destination network after being forwarded by
the switch, the switch will receive the broadcast packet; the switch also belongs to
the subnet. The VLAN of the switch isolates the broadcast domain, it will stop
forwarding the packet to the network. Using the following configuration task, you
can choose to forward the broadcast packet to the network for broadcasting.
Perform the following configuration in system view.
By default, L3 broadcast packets are forwarded.
Displaying and
Debugging IP
Performance
After the previous configuration, display the operation of the IP Performance
configuration in all views, and verify the effect of the configuration. Execute the
debugging command in user view to debug IP Performance configuration.
Tabl e 75 Configure Whether to Send Special IP Packets to CPU
Operation Command
Configure the system to send packets to the
CPU
ip { redirects | ttl-expires |
unreachables }
Configure the system not to send packets to
the CPU
undo ip { redirects | ttl-expires
| unreachables }
Tabl e 76 Configure Whether to Forward L3 Broadcast Packets
Operation Command
Configure forward L3 broadcast packets ip forward-broadcast
Disable forward L3 broadcast packets undo ip forward-broadcast
Tabl e 77 Display and Debug IP Performance
Operation Command
Display TCP connection state display tcp status
Display TCP connection statistics data display tcp statistics
Display IP statistics information display ip statistics
Display ICMP statistics information display icmp statistics
Reset IP statistics information reset ip statistics
Reset TCP statistics information reset tcp statistics