Rate of DHCP Client Packets Processed by DHCP Relay Overview

In instances when multiple IP clients send a large number of packets, DHCP relay is kept busy processing client packets. While DHCP relay processes client packets, it does not process the packets returned from DHCP server at the same rate. This causes a drop in the number of successful transactions between the remote clients and DHCP server.

You can avoid this situation by limiting the number of client packets that DHCP relay processes and assigning a higher priority to packets that DHCP server sends. While DHCP relay monitors the load on the uplink line module, it calculates the number of client packets it can process for the next second. This calculation enables DHCP relay to handle only that number of client packets and process all the packets as calculated. DHCP relay continues to monitor the uplink line module and sets a new rate for packets processed every second. DHCP assigns higher priority to server packets so, when processing an excessive number of packets, DHCP relay discards the client packets first.

Manually Configuring the Maximum Rate of Client Packets Processed Per Second by DHCP Relay

DHCP relay monitors the load on the interface controller (IC). In some cases, when packets are discarded before they reach the IC, the DHCP relay cannot set the maximum client packet rate automatically. You can then manually reconfigure the rate at which DHCP relay processes client packets per second. Manual reconfiguration of the maximum client packet rate is necessary in cases such as the following:

• When DHCP relay forwards a large number of client packets, DHCP server might not be able to process all of them. DHCP server discards the excess packets. You can set the maximum rate of client packets based on the server capability.
• When the uplink line module cannot handle heavy loads, packets are discarded before they reach the IC. You can set the maximum rate of client packets based on the uplink load capacity.
• When DoS parameters are configured on the uplink line module, packets are discarded at the forwarding controller (FC). You can set the maximum rate of client packets based on these DoS parameters.