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Which DHCP options are used when an APC Network Management Device makes a DHCPv4 request?


Issue

Which DHCP options are used when an APC Network Management Device makes a DHCPv4 request?


Product Line
 
 
  • Network Management Card 1 (NMC1) - AP9617, AP9618, AP9619
Devices with an embedded Network Management Card 1 include (but are not limited to): Metered/Switched Rack PDUs (AP78XX, AP79XX), Rack Automatic Transfer Switches (AP77XX, Environmental Monitoring Units (AP9320, AP9340, Netbotz 200)
  • Network Management Card 2 (NMC2) - AP9630/AP9630CH, AP9631/AP9631CH, AP9635/AP9635CH
Devices with an embedded Network Management Card 2 include (but are not limited to): 2G Metered/Switched Rack PDUs (AP86XX, AP88XX, AP89XX), Certain Audio/Video Network Management Enabled products.

 


Environment

  • All serial numbers
  • Firmware versions as noted in line with text below
  • DHCP users

Cause

Below, you will find a list of DHCPv4 options that the APC Network Management Card (AP9617/AP9618/AP9619, AP9630/AP9631/AP9635, and any NMC embedded devices) send/receive in a DHCP Request/Offer. At the current time, option 81 is being investigated for addition (NMC2 products ONLY).


Resolution



Sent by the APC NMC - The NMC uses the following options within a valid DHCP response. (Most of these options are described in RFC2132.)

 


  • Vendor Class Identifier - (option 60) - This option is used by DHCP clients to optionally identify the type and configuration of a DHCP client.  
  • Client Identifier - (option 61) - This option type is most useful for reserved clients. When a reserved client contacts the server, the DHCP service can check and match the client's identifier value to a corresponding identifier used to configure an address reservation in the server's database.
  • User Class - (option 77) - This option is used by a DHCP client to optionally identify the type or category of user or applications it represents.  A DHCP server uses the User Class option to choose the address pool it allocates an address from and/or to select any other configuration option.
  • Host Name - (option 12) - NMC2 only - AOS 5.1.5 and above - This option specifies the name of the client.


Received by the APC NMC The NMC uses the following options within a valid DHCP response. (All of these options except the first are described in RFC2132.) 
 


TCP/IP Options:

  • IP Address (from the yiaddr field of the DHCP response) - The IP address that the DHCP server is leasing to the NMC.
  • Subnet Mask - (option 1) - The Subnet Mask value that the NMC needs to operate on the network.
  • Router, i.e., Default Gateway - (option 3) - The default gateway address that the NMC needs to operate on the network.
  • IP Address Lease Time - (option 51) - The time duration for the lease of the IP Address to the NMC.
  • Renewal Time, T1 - (option 58) - The time that the NMC must wait after an IP address lease is assigned before it can request a renewal of that lease.
  • Rebinding Time, T2 - (option 59) - The time that the NMC must wait after an IP address lease is assigned before it can seek to rebind that lease.
     

Other Options:

  • NTP Server, Primary and Secondary - (option 42) - Up to two NTP servers (primary and secondary) that the NMC can use.
  • NTP Time Offset - (option 2) - The offset of the NMC's subnet, in seconds, from Coordinated Universal Time (UTC).
  • DNS Server, Primary and Secondary - (option 6) - Up to two Domain Name System (DNS) servers (primary and secondary) that the NMC can use.
  • Host Name - (option 12) - Max length of 32 characters - The host name that the NMC will use.
  • Domain Name - (option 15) -  Max length of 64 characters - The domain name that the NMC will use.
  • Boot File Name - (from the file field of the DHCP response, described in RFC2131) - The fully qualified directory-path to a user configuration file (.ini file) to download. The siaddr field of the DHCP response specifies the IP address of the server from which the NMC will download the .ini file. After the download, the NMC uses the .ini file as a boot file to reconfigure its settings.
  • Vendor Specific Information - (option 43) - this option encapsulates the APC cookie and the Boot Mode Transition setting.
The NMC uses this option in a DHCP response to determine whether the DHCP response is valid. This option contains an option in a TAG/LEN/DATA format, called the APC Cookie. This is disabled by default on NMC2 devices.

APC Cookie. Tag 1, Len 4, Data “1APC”

 
Option 43 communicates to the NMC that a DHCP server is configured to service devices. Following, in hexadecimal format, is an example of a Vendor Specific Information option that contains the APC cookie:


Option 43 = 0x01 0x04 0x31 0x41 0x50 0x43


Currently being considered for addition on to the AP9630/AP9631/AP9635 and NMC2 embedded devices:

  • FQDN - (option 81)

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