SD-WAN

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?

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

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

 

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

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
------------------------------

Original Message:
Sent: 03-13-2018 00:00
From: Archive User
Subject: BFD settings for LTE?

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

​

Just wondering, do we have similar type recommendations for satellite and terrestrial links?

gs

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

Original Message:
Sent: 01-08-2019 15:19
From: Adam Morris
Subject: BFD settings for LTE?

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

Original Message:
Sent: 03-13-2018 00:00
From: Archive User
Subject: BFD settings for LTE?

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

​