Optimizing ip performance, Overview, Configuration guidelines – H3C Technologies H3C S12500 Series Switches User Manual
Page 135: Configuration procedure
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Optimizing IP performance
Overview
A customized configuration can help optimize overall IP performance. This chapter describes various
techniques you can use to customize your installation.
Enabling forwarding of directed broadcasts to a
directly connected network
Directed broadcast packets are broadcast on a specific network. In the destination IP address of a
directed broadcast, the network ID identifies the target network, and the host ID is all ones. If a switch is
allowed to forward directed broadcasts to a directly connected network, hackers might mount attacks to
the network. Therefore, the switch is disabled from receiving and forwarding directed broadcasts to a
directly connected network by default. However, you should enable the feature when:
•
Using the UDP Helper function to convert broadcasts to unicasts and forward them to the specified
server.
•
Using the Wake on LAN function to forward directed broadcasts to a host on the remote network.
Configuration guidelines
When you enable forwarding of directed broadcasts to a directly connected network, follow these
guidelines:
•
You can enable forwarding of directed broadcasts to a directly connected network on a VLAN
interface only. Although you can enable this feature on a super-VLAN interface, the switch cannot
forward corresponding directed broadcasts.
•
After this feature is enabled on an interface, the switch automatically generates a forwarding entry
for the network segment where the interface is located. H3C recommends not configuring a static
ARP entry or a static route for the corresponding network segment because of possible
configuration conflict. For example, if an interface on network segment 10.0.0.1/24 has this feature
enabled, the switch generates a forwarding entry of 10.0.0.255/32. If a static ARP entry for
10.0.0.255 is configured, a configuration conflict occurs and logs might be generated. If such a
conflict occurs, you must delete both the static ARP entry and the directed broadcast configuration,
and reconfigure forwarding of directed broadcasts or a static ARP entry. After that, the service
resumes.
•
To forward directed broadcasts, make sure the link status and protocol status of the interface must
be up.
Configuration procedure
To enable forwarding of directed broadcasts to a directly connected network: