Chapter 20: CPE Device Classes
STANDARD Revision 1.0
C4® CMTS Release 8.3 User Guide
© 2016 ARRIS Enterprises LLC. All Rights Reserved.
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Sends configuration information appropriate for that client.
DHCP Relay Agent
To allow DHCP clients on subnets not directly served by DHCP servers to communicate with DHCP servers, DHCP relay
agents are used.
The DHCP client broadcasts on the local link and the relay agent receives the broadcast and transmits it to one or more
DHCP servers.
The relay agent stores its own IP address in the giaddr field of the DHCP packet. The DHCP server uses the giaddr to
determine the subnet on which the relay agent received the broadcast and allocates an IP address on that subnet.
When the DHCP server replies to the client, it sends the reply to the giaddr address. The relay agent then retransmits the
response on the local network.
DHCP Options
DHCP consists of various options determined and defined by CableLab™ for different functionality in a system. Three of the
options that impact the C4/c CMTS are as follows:
Option 43
Option 60
Option 82
Option 43
The DHCP Relay Agent identifies the device class of an eSAFE based on the Vendor Specific Information option 43, sub-
option 2 and sub-option 3, in the DHCP DISCOVER packet.
Option 43.2 — The eSAFEs that are supported are based on the value in the option 43.2, as shown in the table below