Operation Manual – IP Address-IP Performance-IPXH3C S7500 Series Ethernet Switches Chapter 2 IP Performance Configuration2-3To do… Use thecommand… RemarksConfigure to send TTLtimeout packets andunreachable packetsto CPUip { ttl-expires |unreachables }RequiredBy default, Unreachable packets arenot sent to the CPU, while TTLtimeout packets are sent to the CPU2.5 Configuring to Forward Layer 3 Broadcast PacketsBroadcast packets include total-net broadcast packets and directly-connectedbroadcast packets. The destination IP address of a total-net broadcast packet is all 1s(255.255.255.255) or all 0s. A directly-connected broadcast packet is a packet whosedestination IP address is the network broadcast address of a subnet, but the source IPaddress is not in the subnet segment. When a switch forwards this kind of packet, theswitch cannot tell whether the packet is a broadcast packet if the switch is notconnected with the subnet.If a broadcast packet reaches the destination network after being forwarded by theswitch, the switch will receive the broadcast packet, because the switch also belongs tothe subnet. Because the VLAN of the switch isolates the broadcast domain, the switchwill stop forwarding the packet to the network. Using the following configuration tasks,you can choose to forward the broadcast packet to the network for broadcast.Follow these steps to configure to forward layer 3 broadcast packets in system view:To do… Use the command… RemarksEnter system view system-view —Configure to forwardLayer 3 broadcastpacketsip forward-broadcastRequiredBy default, the switchdoes not forward Layer 3broadcast packets.
