Belkin PF31 Specifications download pdf (Page 22)

Basic Configuration and Operation

193

BD Address: 00:0A:D9:15:CB:B4

Device Name: ED P800

LMP Version: 1.1 (0x1) LMP Subversion: 0x9040

Manufacturer: Ericsson Mobile Comunications (0)

Features: 0xff 0xfb 0x01 0x00

<3-slot packets> <5-slot packets> <encryption> <slot offset>

Pinging a Remote Device

The ping command is an incredibly useful tool for discovering whether

remote computers are reachable over a TCP/IP network. BlueZ has an ana-

log to ping, called l2ping. Its name refers to the fact that it attempts to create

a connection to the device using the logical link control and adaptation proto-

col (L2CAP), the lowest-level link-based protocol in Bluetooth.

In other words, before despairing because you cannot connect to a device,

check it with l2ping. There may be a fault with software higher up the chain;

l2ping enables you to determine whether a basic connection can be estab-

lished with a remote device. Here’s an example of l2ping in action (you need

to run l2ping as root):

# l2ping 00:0A:D9:15:CB:B4

Ping: 00:0A:D9:15:CB:B4 from 00:80:98:24:15:6D (data size 20) ...

0 bytes from 00:0A:D9:15:CB:B4 id 200 time 54.85ms

0 bytes from 00:0A:D9:15:CB:B4 id 201 time 49.35ms

0 bytes from 00:0A:D9:15:CB:B4 id 202 time 34.35ms

0 bytes from 00:0A:D9:15:CB:B4 id 203 time 28.33ms

4 sent, 4 received, 0% loss

If you have not yet paired your computer with the device with

which you are testing, using l2ping may result in a “permis-

sion denied” error. To remedy this, you must either pair your

device with the computer (see “Bonding/Pairing” later in this

chapter) or ensure that the remote device is discoverable.

Why Isn’t Scanning Instantaneous?

The reason scanning can take a long time is because a Bluetooth inquiry is

being performed. As Bluetooth devices frequency-hop, inquiry cannot be

instantaneous. The device performing the inquiry transmits a special code on

two consecutive frequencies. When the other devices’ hop patterns take them

onto those frequencies, they listen for a repetition of that code and then indi-

cate their presence to the inquirer.

1 2 ... 17 18 19 20 21 22 23 24 25 26 27 ... 45 46

No comments

Belkin PF31 Specifications Page 22