We use 100 kbits per call session of G711U. We took a while to get a good working config on junos to make sure only voip traffic comes in to the SM tagged for high priority. The SM only goes by the Priority Precedence selection to check either 802.1p or DSCP to determine transmit channel and you need to make sure inbound ethernet traffic to the SM is tagged correctly so that voip, and only voip, ends up in the high priority channel.
We also ran into issues with burst allocation and burst rates. In order for the high priority channel to work correctly on 450 platform we found you must set the Sustained Uplink/Downlink Data Rate and the Uplink/Downlink Burst Allocation to be the same (customer regular bandwidth + high priority bandwidth) and the Max Burst Uplink/Downlink Rates to double the Total Sustained Uplink/Downlink. We confirmed in extensive testing that if we simply enable a high priority channel on a normal customer, when the user maxes his upload or download we see packet loss on the high priority channel even when the upload/download is all low priority traffic and the high priority channel is not being 100% used. Why is this? We're not sure but our network engineers did pretty extensive testing and we consistently saw packet loss when configured with a high priority channel and a "normal" customer deployment of Sustained Down 4 Mbit / Sustained Up 1 Mbit, Downlink Burst Allocation 120000 and max burst downlink of 10000. Timothy Alexander Amplex Internet www.amplex.net [email protected]
From: Brian Sullivan<[email protected]> To:"[email protected]" <[email protected]> Subject: [AFMUG] High Priority Uplink / Downlink What do other operators set for the High Priority Uplink / Downlink CIR
that works best for VOIP?
