Subject: Re: ZLB Ack.

From: Barney Wolff <[email-masked]>
Date: Fri, 14 Apr 2000 09:51 EDT

The queue is the output queue.  From the LNS's point of view when it
gets the SCCCN, it has nothing to send and must ack the SCCCN, so it
sends the ZLB.  It would be a (imho) needless sophistication for the
LNS to implement delayed acks and hope that the LAC will send another
packet quickly.  The cost of L2TP is the header applied to each PPP
frame, not the very few packets exchanged to setup/teardown tunnels
and sessions.

Regards,
Barney Wolff

> From: HOULLIER Francis FTRD/DMI/CAE <[email-masked]>
> Date: Fri, 14 Apr 2000 10:08:16 +0200
> 
> What is the condition to send a ZLB Ack (see the example below), is this a
> timer or something else ? The rfc says only that "the ZLB Ack is sent if
> there are no futher messages waiting in the queue".
> 
> LAC						LNS
> 
> SCCRQ ---->
> 					<----SCCRP
> SCCCN ---->
> 					<----ZLB ACK
> 
> But generally after the SCCCN, the LAC sends an ICRQ and the LNS can't send
> the ZLB ACK.
> Thank you for your help.
>