The device sensor is used to gather endpoint data from network devices. The endpoint information helps to complete the profiling capability of devices. Profiling is the process of determining the endpoint type based on the information gleaned from various protocol packets from an endpoint during its connection to a network. The HTTP Gleaning feature allows the device sensor to extract the HTTP packet type, length, value (TLV) to get information about the type of the end device.

User-Agent is one such TLV that contains information such as end-device operating system details and the browser used for the operation. This information is gleaned by the device sensor. The device classifier can use this information to ascertain the device type.

HTTP User-Agent requires the following functionalities to support HTTP gleaning.

• HTTP packet handler
• HTTP packet header parser
• HTTP TLV gleaner (DSensor shim)

Device sensors use filters to include or exclude specific TLVs to be stored by the device sensor cache. The filter configuration is a two-step process.

1. Creating a protocol filter list.
2. Applying the protocol filter list to the filter specification.

The protocol filter list is a protocol-specific list that stores the list of TLVs that are configured as part of this list. You can configure any number of filter lists for a single protocol.

The following is sample output from the show device-sensor cache [all | interface | mac] command. The output shows that the HTTP TLVs are gleaned by the device sensor.

Device# show device-sensor cache all

Device: c8e0.eb17.0b6f on port Capwap0
--------------------------------------------------
Proto    Type:Name                       Len Value
HTTP     1:user-agent              83 01 51 4D 6F 7A 69 6C 6C 61 2F 35 2E 30 20 28 4D
                                   61 63 69 6E 74 6F 73 68 3B 20 49 6E 74 65 6C 20
                                   4D 61 63 20 4F 53 20 58 20 31 30 2E 38 3B 20 72
                                   76 3A 32 35 2E 30 29 20 47 65 63 6B 6F 2F 32 30
                                   31 30 30 31 30 31 20 46 69 72 65 66 6F 78 2F 32
                                   35 2E 00
DHCP    54:server-identifier       6 36 04 C0 A8 0A 01
DHCP    50:requested-address       6 32 04 C0 A8 0A 16
DHCP     0:                								8 00 06 44 AD D9 03 3B 00
DHCP   255:end                     2 FF 00
DHCP    12:host-name               14 0C 0C 73 70 72 61 73 61 64 73 2D 6D 61 63
DHCP    61:client-identifier       9 3D 07 01 C8 E0 EB 17 0B 6F
DHCP    57:max-message-size        4 39 02 05 DC
DHCP    55:parameter-request-list  11 37 09 01 03 06 0F 77 5F FC 2C 2E
DHCP    53:message-type            3 35 01 03

The following table describes the significant fields shown in the display: