Navigation

    Netgate Discussion Forum
    • Register
    • Login
    • Search
    • Categories
    • Recent
    • Tags
    • Popular
    • Users
    • Search

    Jitter Buffer

    Traffic Shaping
    4
    6
    1524
    Loading More Posts
    • Oldest to Newest
    • Newest to Oldest
    • Most Votes
    Reply
    • Reply as topic
    Log in to reply
    This topic has been deleted. Only users with topic management privileges can see it.
    • M
      mdonnolo last edited by

      I am relaying a T1 over ethernet, using an Adtran MX408e.

      Since it is a TDM interface packets must be received prior to the jitter buffer on the MX408e exhausting.  The MX408e only has a max  jitter buffer of 100ms.  The jitter on my present connection is ~300ms.

      Has someone done this with traffic shaping or dummynet?  I have been playing with queues to no avail.

      It is not VOIP traffic so a short delay will not pose any problems.

      1 Reply Last reply Reply Quote 0
      • H
        Harvy66 last edited by

        I'm not entirely privy to T1 terminology, so I may make some incorrect assumptions.

        My question is do you know why the jitter is so incredibly high? T1s are rated for 1-5ms of jitter and Ethernet is typically in the microseconds. You're talking about latencies 100x greater that normal. While the max buffer may be 100ms, you shouldn't be filling a buffer on a synchronous connection.

        1 Reply Last reply Reply Quote 0
        • Derelict
          Derelict LAYER 8 Netgate last edited by

          Are you relaying a T1 over "ethernet" or ethernet then the internet.  A good switch should be able to forward frames with latency measured in microseconds, not 300 milliseconds.

          1 Reply Last reply Reply Quote 0
          • M
            mdonnolo last edited by

            The set up looks like this:

            +–----+          +--------+
                T1+--+MX408e++ETHERNET+-+PFSENSE |+----+
                      +------+          +--------+    |
                                                        |
                      MOBILE CONNECTION/OPENVPN        |
              +----------------------------------------+
              |
              |
              |  +-------+          +------+
              +-+|PFSENSE++ETHERNET++MX408e+--+T1
                  +-------+          +------+

            The T1s are either end are used for relaying telemetry data from two arcane pieces of equipment between power plants a delay of under 2 seconds end to end is acceptable.

            The jitter comes when the connection is piped over the mobile connection.  Asterisk and FreeSwitch seemed to have some jitter buffering capabilities, but I am not sure how to implement..

            The buffer would work like this (assume 1 packet per millisecond):
            -Wait and capture 300 packets–->Send 1 packet every millisecond.

            1 Reply Last reply Reply Quote 0
            • B
              BeerCan last edited by

              I might be confused but wouldn't the 100ms buffer on the mx408e always be the limiting factor in the above scenario?

              1 Reply Last reply Reply Quote 0
              • Derelict
                Derelict LAYER 8 Netgate last edited by

                I think you're going to have a hell of a time trying to get a TDM circuit transported over a 300ms RTT VPN link.  No amount of traffic shaping is going to make that any better.  SIP trunking would probably be better, but 300ms is a lot for that too.

                1 Reply Last reply Reply Quote 0
                • First post
                  Last post

                Products

                • Platform Overview
                • TNSR
                • pfSense
                • Appliances

                Services

                • Training
                • Professional Services

                Support

                • Subscription Plans
                • Contact Support
                • Product Lifecycle
                • Documentation

                News

                • Media Coverage
                • Press
                • Events

                Resources

                • Blog
                • FAQ
                • Find a Partner
                • Resource Library
                • Security Information

                Company

                • About Us
                • Careers
                • Partners
                • Contact Us
                • Legal
                Our Mission

                We provide leading-edge network security at a fair price - regardless of organizational size or network sophistication. We believe that an open-source security model offers disruptive pricing along with the agility required to quickly address emerging threats.

                Subscribe to our Newsletter

                Product information, software announcements, and special offers. See our newsletter archive to sign up for future newsletters and to read past announcements.

                © 2021 Rubicon Communications, LLC | Privacy Policy