This is an option defined by CableLabs to carry the information necessary to configure PacketCable devices. DOCSIS mandates that this option is filled with the MAC address of the cable modem and applies to all traffic from the cable modem, or any device appearing from behind that cable modem It is commonly used as a subscriber identifier in DOCSIS-based networks. This is an identifier added by the relay agent to identify the client. This is commonly used as a subscriber identifier in DSL-based networks. This is an identifier added by the relay agent to indicate which interface the client is on. Some of the common options are listed below This option carries many other sub-options that are added by relay agents and not the clients themselves. (Note: Address Commander can do some dynamic file name generation for this name.) Note that often data put into option 67 does not actually appear in the DHCP packet as option 67, but may be moved into the “”file”” field of the DHCP packet. Additionally, the FQDN may have been resolved to an IP address and also placed in the “”siaddr”” field of the DHCP packet.ĭefines the filename that is to be downloaded from the server specified in option 66. Note that often the data put into option 66 does not actually appear in the DHCP packet as option 66, but may have been moved into the “”same”” field of the DHCP packet. For example, the DOCSIS specifications state that if the device is DOCSIS-compliant, option 60 must start with “”DOCSIS”” (and also include other details).ĭefines the FQDN or IP address (or cluster identifier) that the device should use to download the file specified in option 67. The DHCP specification does not define what values go into this field, but other specifications do. CableLabs’ eDOCSIS specification, for example, defines certain sub-options that appear in this optionĭefines some identifier from the client that may identify the client’s device class. Individual vendors can define different pieces of data that may be found in this option. )ĭefines configuration data that is not defined in the standard DHCP RFCs. 15ĭefines the domain name to use for the device (e.g. The log server the client is going to forward logs to.ĭefines the FQDN for this device (e.g. The IP address of the DNS server(s) to use This is related to the Time Zone Offset option. Tells the client the IP address of a time server that can determine the client’s current time. Tells the client which router is the default Gateway. (Eight hours * 60 minutes/hour * 60 seconds/minute) This field would be filled with “”- 28800″”. For example, Pacific Standard Time is GMT Ð 8 hours. Informs the client about the time zone offset, in seconds. The subnet mask to apply to the address that is assigned to the client. I recommend you check that one out as well. A few years back, I wrote an article on how DHCP v4 really works. When configuring DHCP in various system, you sometimes requires specific options such as when you configure Cisco Phones and need to tell the phones where to get their boot image from using option 150.
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