Basic VoIP shaping from scratch - either its high or low…

  • Greetings,

    After reading a few threads like these:,6338.0.html,7502.0.html

    I feel I am beginning to understand how things work a fair bit better, however Im wanting to simplify life, as few queues and rules as possible ;) At the moment no matter what I try, I always get errors … :(

    The ADSL Modem (Linksys AM300) is operating in half-bridge mode to an Alix 6b2 500MHz w/256MB Ram on a 128MB CF Card.
    The modem syncs at approx 12000kbps down and 1000kbps up.

    Ideally Id like to establish the 2x root queues (Currently Ive got them as 9000kbps & 700kbps -- Im not sure how "safe" I should be), then establish a "priority" queue which obviously has the VoIP and any other required traffic, then have a "bulk" queue which is EVERYTHING else, http, ftp, email, whatever ...

    The VoIP is connecting from an asterisk box on the LAN side to the ITSP via an IAX2 trunk on UDP Port 4569. We're using iLBC 13.3kbps and expect to do a max of 3x concurrent calls.
    Based on the calculations from here:
    If I change it to iLBC 13.3kbps, PPPoA & use IAX2 Trunked, then I set it to 3 calls it tells me I need 95kbps of bandwidth. So I'll round it off to 100kbps just coz I can.

    Using 1/7 of all the connection is not much, is it possible to permanently reserve that much with max priority for VoIP traffic, with the possibility of it asking for more should it need it?

    I wouldnt think the rest of the connection will need to "borrow" from the VoIP queue, as having 8900kbps download & 600kbps upload is still plenty for what we're wanting to be doing.

    Im also not entirely sure what the values should be for RED / ECN / RIO, as well as the "REALTIME" Service Curve values. We wont always have 3x concurrent calls through it, but if that bandwidth is permanently reserved, we wont really care too much...

    Also, I can see the qwanacks & qlanacks queues after Ive run the Wizard, and I can see things going through them when I view the Queues Status, however I cant see any rules directing anything to them so I have no idea what they'er used for as current etc :-/ Searching around I mostly find people telling you to tweak them, but not specifically why / what they're for.

    Any suggestions / comments / recommendation / help would be greatly appreciated

    Kind regards


  • Ive also been reading the likes of this:

    Basically my questions would be:
    I have a connection, we'll say Im generally always getting 10000 download & 600 upload

    My problem is:
    I need a constant 100Kbps for VoIP, and I almost need it gauranteed.
    Ive tried fluffing around with the shaper so that I class everything thats not VoIP or ACK as p2p and it gets lowest priority, but I still get a relatively bad call, the same if I leave it on or dont…

    Any ideas about where I should start would be much appreciated

  • This is a very old post, but could you give a follow up to what you did to fix your problem, if you ever got it resolved?

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