Re: [Bluez-users] MTU in l2test

Marcel Holtmann
2005-01-03T11:43:26Z

Hi Manjunath,

> > > I am using anycom-120 dongles and using the l2test utility. I am also
> > > setting the incoming and outgoing mtu values (imtu and omtu variables)
> > > to the same value, say 65000 bytes. My 'datasize' is about 45000
> > > bytes. I get the error as mentioned above.
> >
> > what is the output of "hciconfig -a" of the Anycom dongle. Check when
> > this error occurs. Do you see it only when calling the send()/write()
> > function? Maybe there is a buffer problem. What do you see with hcidump?
> > Is the MTU correctly negotiated?
>
> hi marcel,
>
> the "hciconfig -a" shows
>
> hci0: Type: USB
> BD Address: 00:0B:0D:30:5D:EA ACL MTU: 120:20 SCO MTU: 64:0
> UP RUNNING PSCAN ISCAN
> RX bytes:114526 acl:28 sco:0 events:15460 errors:0
> TX bytes:4857089 acl:39552 sco:0 commands:1400 errors:0
> Features: 0xff 0xff 0x05 0x00 0x00 0x00 0x00 0x00
> Packet type: DH5
> Link policy:
> Link mode: SLAVE ACCEPT
> Name: ''
> Class: 0x000000
> Service Classes: Unspecified
> Device Class: Miscellaneous,
> HCI Ver: 1.1 (0x1) HCI Rev: 0x0 LMP Ver: 1.1 (0x1) LMP Subver: 0x757
> Manufacturer: Silicon Wave (11)

leave the packet types to the default (all on).

> I get this error when i use the send() function to pump the data out.
> May be there is a problem with the HCI buffer. Is there some way to
> add a delay. The L2CAP connection is correctly established and the MTU
> is also correctly negotiated to the set value (65000) as seen in the
> hcidump on both sides.

The problem is maybe inside the l2cap_do_send() kernel function. I never
played with MTUs such big.

You should think about using RFCOMM, because this is a stream and so MTU
less.