Re: E1 interface, layer 2

On Tue, Mar 10, 2009 at 03:24:00PM +0100, Klaus-Peter Junghanns wrote:

i am staring at the sources right now, figuring out how openbsc uses which part of misdn to send/receive frames over the e1 link. I think it's doing something like this (please correct me if i am wrong:

i hope it's not too hard to figure it out, the e1_input abstraction makes it a bit more difficult than it used to be.

• use timeslot 1 in hdlc mode for the signalling link

yes. And use a number (minimum: two) DLC's with each their own pair of SAPI/TEI.

• use misdns layer 2 to handle the TEI assignment, etc

yes.

What i am wondering about is:

• which ETSI standard describs layer 2 for GSM abis?

it's gsm 08.56 (ETSI TS 100 595). you also might want to look at 08.51 / 08.52 and 08.54.