Riverstone Networks WICT1-12 - Manual (Page 117)

Riverstone Networks RS Switch Router User Guide Release 8.0 7-5
CMTS Configuration Guide Connecting and Configuring the Downstream
7.3.4 DHCP Servers
A Dynamic Host Configuration Protocol (DHCP) server must be installed at the headend site to assign an IP address
to each cable modem in compliance with DOCSIS specification. The DHCP server must also offer a time-of-day server
option that is compliant with RFC-868.
Note In HFC networks where a small number of cable modems are installed, the
DHCP/TFTP server can be installed somewhere on the wide-area network (WAN)
instead of at the headend. In a routed configuration, the RS 8000/8600 can be
configured as a proxy device to forward DHCP requests from cable modems to the
DHCP server.
The CMTS module uses these assigned IP addresses to identify individual cable modems operating on the network.
The CMTS module stores DOCSIS registration parameters for future reference.
Note The RS 8000/8600 DHCP server should not be used.
When a DHCP server is configured in a network, the server assigns an IP address to each cable modem when a
connection is made to the network. The RS 8000/8600 periodically polls the cable modems on the network to see if
the network connection is still active. When the connection to the network ends, the IP address is reassigned, as needed,
to other cable modems establishing a connection to the network.
If a cable modem’s IP address assignment expires and the DHCP server is not accessible, the cable modem will not
operate as a bridge to other network devices until another IP address is obtained. When a cable modem enters ranging
and registration mode to obtain another IP address, the RS 8000/8600 will not handle any requests to or from other
devices attached to the cable modem.
7.3.5 DNS and TFTP Servers
In conjunction with the DHCP server, a Domain Name Server (DNS) server must be installed to translate names of
network nodes into IP addresses, and a Trivial File Transfer Protocol (TFTP) server must be installed to transfer
configuration files over the network for field support and future software upgrades.
7.4 CONNECTING AND CONFIGURING THE
DOWNSTREAM
After installing the RS 8000/8600 router chassis and the CMTS module at the headend site, connect the CMTS module
to the HFC network and configure the network. The following sections describe how to connect to and configure the
downstream.