SD-WAN

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Ask questions and share experiences with SD-WAN and Session Smart Router (formerly 128T).
  • 1.  BFD settings for LTE?

     
    Posted 03-13-2018 00:00
    I've got a deployment using LTE, and I'm looking to keep the data usage low, while still getting decent forwarding detection and path quality information. Anyone have some BFD settings they like when peering across LTE interfaces?


  • 2.  RE: BFD settings for LTE?

    Posted 03-13-2018 00:00

    Reid,

    Thank you for reaching out. As you know, 128T Routers leverage BFD to monitor multiple capabilities of paths between 128T Routers:

    • Path Availability
    • Path Health (Jitter, Packet Loss, Latency, and MOS Score)
    • Presence of Stateful Tracking Devices (Firewalls, CG NAT devices, etc).

     

    While these capabilities provide fine-grained analytics and service SLA monitoring, they can be problematic for metered connections. As of software version 3.1.9 with the default BFD settings, the 128T router will expend 1.6 GB per month per peer path. In many environments, the LTE path is often the path of last resort, so the path availability and fine-grained SLA measurements don't need to be as aggressive.

     

    The following recommended configuration changes for metered connections will reduce BFD Bandwidth Usage to 146 MB per month per peer path:

    bfd state enabled desired-tx-interval 60000 required-min-rx-interval 60000 required-min-echo-interval 60000 authentication-type sha256 multiplier 3 link-test-interval 120 link-test-length 10 exit

    Typically adjacencies are dynamically discovered and automatically generated, leveraging settings contained within the neighborhood object. As such, it is recommended to place these configurations in the neighborhood that is being leveraged for LTE network interfaces.

     

    EDIT: one can also add to the neighborhood configuration to disable the firewall detection test (udp-transform mode always-transform) to save an additional 30 MB per month per peer path.

    udp-transform mode always-transform exit

    If you have a specific circumstance that needs a more thorough investigation, please let us know!

     

    Thomas Sullivan

    128 Technology



  • 3.  RE: BFD settings for LTE?

     
    Posted 03-13-2018 00:00

    Thanks! Do you also use the udp-transform setting `mode always-transform`, to avoid use of FW detection tests?

    udp-transform mode always-transform exit

     



  • 4.  RE: BFD settings for LTE?

    Posted 03-13-2018 00:00

    Reid L Stidolph 

    You raise a good point. As of version 3.1.9, the default periodicity for the BFD firewall detection test for UDP transform was moved from every 10 seconds to every 5 minutes. That default behavior change alone drastically reduced the bandwidth consumed by the BFD firewall detection test (30% per month per peer path).

    Per your recommendation, one can also add to the neighborhood configuration to disable the firewall detection test (udp-transform mode always-transform) to save an additional 30 MB per month per peer path.

    Combining the other aforementioned settings with udp-transform mode set to always-transform, the LTE usage for BFD would be ~120 MB per month per peer path.

     

    Thomas Sullivan

    128 Technology



  • 5.  RE: BFD settings for LTE?

     
    Posted 01-08-2019 15:19
    As of #4.0.0, one parameter has been deprecated. Here's an example of the LTE recommended BFD settings in 4.0.0:
    admin@grimlock.seattle-site-02-lanner# configure authority router seattle-site-02-lanner node grimlock device-interface lte-wan network-interface lte-digi neighborhood lte show
    name               lte
    peer-connectivity  outbound-only
    vector             lte
    
    bfd
        state                     enabled
        desired-tx-interval       60000
        required-min-rx-interval  60000
        link-test-interval        120
    exit
    
    udp-transform
        mode  always-transform
    exit​


    Also, to note, be sure to adjust the BFD timers on the far end (head end router) neighborhood as well to match.



    ------------------------------
    Adam Morris
    Sales Engineer
    WA
    (206) 617-4999
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  • 6.  RE: BFD settings for LTE?

     
    Posted 07-20-2020 15:27
    Just wondering, do we have similar type recommendations for satellite and terrestrial links?

    gs

    ------------------------------
    Gene Shtirmer
    Sales Engineer
    Randolph NJ
    (973) 610-5676
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