Supported Platforms
Related Documentation
- EX, J, M, MX, QFX, T Series
- show subscribers
- M, MX Series
- Centrally Configured Opaque DHCP Options
Monitoring DHCP Options Configured on RADIUS Servers
Purpose
View information for DHCP options that are centrally configured on a RADIUS server and that are distributed using Juniper Networks VSA 26-55 (DHCP-Options).
Action
To display information for opaque DHCP options:
user@host> show subscribers detail
Type: DHCP IP Address: 192.168.9.7 IP Netmask: 255.255.0.0 Logical System: default Routing Instance: default Interface: demux0.1073744127 Interface type: Dynamic Dynamic Profile Name: dhcp-prof-23 MAC Address: 00:10:95:00:00:98 State: Active Radius Accounting ID: jnpr :2304 Session Timeout (seconds): 3600 Idle Timeout (seconds): 600 Login Time: 2011-08-25 14:43:52 PDT DHCP Options: len 52 35 01 01 39 02 02 40 3d 07 01 00 10 94 00 00 08 33 04 00 00 00 3c 0c 15 63 6c 69 65 6e 74 5f 50 6f 72 74 20 2f 2f 36 2f 33 2d 37 2d 30 37 05 01 06 0f 21 2c
Meaning
DHCP Options: len 52 35 01 01 39 02 02 40 3d 07 01 00 10 94 00 00 08 33 04 00 00 00 3c 0c 15 63 6c 69 65 6e 74 5f 50 6f 72 74 20 2f 2f 36 2f 33 2d 37 2d 30 37 05 01 06 0f 21 2c
The DHCP options output provides the following information:
- The len field is the total number of hex values in the message.
- The hex values specify the type, length, and value (TLV) of DHCP options, and are converted to decimal to identify the DHCP options, as defined in RFC 2132.
The number of hex values that make up a particular DHCP option varies, depending on the length of the option. For example, the first DHCP option specified in the output includes three sets of hex values (35 01 01). The first hex value (35) identifies the option type, the second value (01) indicates the length of the value entry, which is this case is one set of hex values. The third hex value (01) specifies the value for the DHCP option.
In the second DHCP option specification (39 02 02 40), the hex value 39 is the type, and the length of 02 specifies that two sets of hex entries make up the value for the option. Therefore, this option specification uses four sets of hex entries; one for the type (39), one to specify the length (02), and two for the option value (02 40).
The third DHCP option is specified by the hex values 3d 07 01 00 10 94 00 00 08. The hex value 3d is the type, followed by the length (07), which specifies that the next seven sets of hex entries make up the value for the option. Therefore, this option specification uses a total of nine sets of hex entries; one for the type (3d), one to specify the length (07), and seven for the value of the DHCP option (01 00 10 94 00 00 08).
Table 1 describes the first two options in more detail.
Table 1: DHCP Options Description
Option | Type | Length | Value |
|---|---|---|---|
35 01 01 | 35 = decimal 53 (Code 53 in RFC 2132 is the DHCP Message Type option) | 01 = the length of the option is one set of hex values (the next set in the list) | 01 = value of the message type that is described in RFC 2132. The code 01 specifies a message type of DHCPDISCOVER. |
39 02 02 40 | 39 = decimal 57 (Code 57 is the Maximum DHCP Message Size option) | 02 = the length of the option is two sets of hex values (the next two sets in the list) | 0240 = converted to a length of 576 octets |
Related Documentation
- EX, J, M, MX, QFX, T Series
- show subscribers
- M, MX Series
- Centrally Configured Opaque DHCP Options
Published: 2013-02-11
Supported Platforms
Related Documentation
- EX, J, M, MX, QFX, T Series
- show subscribers
- M, MX Series
- Centrally Configured Opaque DHCP Options
