Cisco 7604 Configuration Guide - Page 180

Option Code, Description, Table 8-1, Unsupported DHCP Options

Page 180 highlights

Configuring DHCP Chapter 8 Configuring IP Routing and DHCP Services Table 8-1 Unsupported DHCP Options Option Code 52 53 54 58 59 61 67 82 255 Description DHCPOPT_OPTION_OVERLOAD DHCPOPT_MESSAGE_TYPE DHCPOPT_SERVER_IDENTIFIER DHCPOPT_RENEWAL_TIME DHCPOPT_REBINDING_TIME DHCPOPT_CLIENT_IDENTIFIER DHCPOPT_BOOT_FILE_NAME DHCPOPT_RELAY_INFORMATION DHCPOPT_END Specific options, DHCP option 3, 66, and 150, are used to configure Cisco IP Phones. See the "Using Cisco IP Phones with a DHCP Server" section on page 8-38 topic for more information about configuring those options. Using Cisco IP Phones with a DHCP Server Enterprises with small branch offices that implement a Cisco IP Telephony Voice over IP solution typically implement Cisco CallManager at a central office to control Cisco IP Phones at small branch offices. This implementation allows centralized call processing, reduces the equipment required, and eliminates the administration of additional Cisco CallManager and other servers at branch offices. Cisco IP Phones download their configuration from a TFTP server. When a Cisco IP Phone starts, if it does not have both the IP address and TFTP server IP address preconfigured, it sends a request with option 150 or 66 to the DHCP server to obtain this information. • DHCP option 150 provides the IP addresses of a list of TFTP servers. • DHCP option 66 gives the IP address or the hostname of a single TFTP server. Cisco IP Phones might also include DHCP option 3 in their requests, which sets the default route. Cisco IP Phones might include both option 150 and 66 in a single request. In this case, the FWSM DHCP server provides values for both options in the response if they are configured on the FWSM. You can configure the FWSM to send information for most options listed in RFC 2132. The following table shows the syntax for any option number, as well as the syntax for commonly-used options 66,150, and 3: • To provide information for DHCP requests that include an option number as specified in RFC 2132, enter the following command: hostname(config)# dhcpd option number value • To provide the IP address or name of a TFTP server for option 66, enter the following command: hostname(config)# dhcpd option 66 ascii server_name • To provide the IP address or names of one or two TFTP servers for option 150, enter the following command: hostname(config)# dhcpd option 150 ip server_ip1 [server_ip2] 8-38 Catalyst 6500 Series Switch and Cisco 7600 Series Router Firewall Services Module Configuration Guide using ASDM OL-20748-01

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8-38
Catalyst 6500 Series Switch and Cisco 7600 Series Router Firewall Services Module Configuration Guide using ASDM
OL-20748-01
Chapter 8
Configuring IP Routing and DHCP Services
Configuring DHCP
Specific options, DHCP option 3, 66, and 150, are used to configure Cisco IP Phones. See the
“Using
Cisco IP Phones with a DHCP Server” section on page 8-38
topic for more information about
configuring those options.
Using Cisco IP Phones with a DHCP Server
Enterprises with small branch offices that implement a Cisco IP Telephony Voice over IP solution
typically implement Cisco CallManager at a central office to control Cisco IP Phones at small branch
offices. This implementation allows centralized call processing, reduces the equipment required, and
eliminates the administration of additional Cisco CallManager and other servers at branch offices.
Cisco IP Phones download their configuration from a TFTP server. When a Cisco IP Phone starts, if it
does not have both the IP address and TFTP server IP address preconfigured, it sends a request with
option 150 or 66 to the DHCP server to obtain this information.
DHCP option 150 provides the IP addresses of a list of TFTP servers.
DHCP option 66 gives the IP address or the hostname of a single TFTP server.
Cisco IP Phones might also include DHCP option 3 in their requests, which sets the default route.
Cisco IP Phones might include both option 150 and 66 in a single request. In this case, the FWSM DHCP
server provides values for both options in the response if they are configured on the FWSM.
You can configure the FWSM to send information for most options listed in RFC 2132. The following
table shows the syntax for any option number, as well as the syntax for commonly-used options 66,150,
and 3:
To provide information for DHCP requests that include an option number as specified in RFC 2132,
enter the following command:
hostname(config)#
dhcpd option
number
value
To provide the IP address or name of a TFTP server for option 66, enter the following command:
hostname(config)#
dhcpd option 66
ascii
server_name
To provide the IP address or names of one or two TFTP servers for option 150, enter the following
command:
hostname(config)#
dhcpd option 150
ip
server_ip1
[
server_ip2
]
52
DHCPOPT_OPTION_OVERLOAD
53
DHCPOPT_MESSAGE_TYPE
54
DHCPOPT_SERVER_IDENTIFIER
58
DHCPOPT_RENEWAL_TIME
59
DHCPOPT_REBINDING_TIME
61
DHCPOPT_CLIENT_IDENTIFIER
67
DHCPOPT_BOOT_FILE_NAME
82
DHCPOPT_RELAY_INFORMATION
255
DHCPOPT_END
Table 8-1
Unsupported DHCP Options
Option Code
Description