- This topic has 9 replies, 1 voice, and was last updated 8 years, 9 months ago by Vicky_RF.
18th April 2012 at 07:33 #68105Vicky_RFGuest
Pls help me,what is the LLC Re-transmission ,is at at the RLC layer??19th April 2012 at 17:41 #68106pixGuest
it’s probably at llc layer ! LLC is managed by the SGSN.
but (as far as i recall) LLC is not supposed to retransmit data (except some signalling, i believe). The retransmission is done at higher layers (applications, such as TCP).
pix21st April 2012 at 08:53 #68107Vicky_RFGuest
Thanks Pix,should we need to consider this LLC Re-transmission in our UL/DL TBF Establishment Success Rate formula.21st April 2012 at 11:53 #68108pixGuest
how would the llc retransmission impact the TBF establishment ?
please, more details !
pix23rd April 2012 at 16:40 #68109rajGuest
LLC retransmission occurs at the LLC layer and not at the RLC layer.
Have you ever wondered why there is an requirement of another logical link, i.e. LLC, above RLC, between the MS and SGSN?
There could scenario where LLC retransmissions will be required, for example, for an application that works in an unacknowledged mode and which do not have an error checking and correction mechanism on it own.
Due to LLC retransmission, timer running at TCP layer may expire. This will make the TCP to re-send the Network PDU (NPDU), for whom an ack was awaiting, to the LLC layer , which could further add to a delay in the TBF establishment or even a dip in throughput.
Hope above explains your concerns.
-Raj/www.telecomspeaks.com24th April 2012 at 09:35 #68110Vicky_RFGuest
Do u have the data flow for the same.26th April 2012 at 20:13 #68111pixGuest
are you saying that the application layer might force the LLC to work in an ack mode, thus enabling LLC retransmissions?
Maybe I am wrong, but as far as i remember, LLC ack mode is enabled only for specific messages (flow control or signalling msg, or something like this).
For user place, LLC is always unack.
==> no llc retransmission
==> no delay due to LLC retransmission
pix26th June 2012 at 06:53 #68112Vicky_RFGuest
How are you
LLC Transmission is happened due to resource re-allocation request made at RLC layer???26th June 2012 at 18:43 #68113pixGuest
no. But please expand your question, it looks like you are facing a problem ?
pix27th June 2012 at 09:15 #68114Vicky_RFGuest
Actually I want to know when UL/DL LLC frame changes during the UL/DL GPRS TBF transmission at that time resource re-allocation request is made at RLC layer for UL/DL TBF.
And also let me know how the LLC frame changes.