Using dyn-gw plugin vs. freifunk-gwcheck

[Ben West]

Hello again,

I'm curious if anyone is aware of any benefits to using either of these
methods for detecting Internet connectivity on a OpenWRT gateway node:

1. The "ping" parameter for dyn-gw plugin (readme for v0.6.5.4 below):
https://github.com/opentechinstitute/olsrd/blob/release-0.6.5.4/lib/dyn_gw/README_DYN_GW

2. The freifunk-gwcheck scripting-based tool:
http://luci.subsignal.org/trac/browser/luci/trunk/contrib/package/freifunk-gwcheck

I had been trying out freifunk-gwcheck with its default config on nodes
running olsrd v0.6.5.4 and with SmartGateway enabled. However, I was
finding gateway nodes occasionally losing their default route entirely
after outages in their upstream Internet connection. That is,
freifunk-gwcheck would detect the outage and modify node's local routing
table, but it would apparently not recover when the outage was resolved.
I'm not asking on this list for any further into about freifunk-gwcheck
operation, as this is not the right venue.

The ping parameter for the dyn-gw plugin, however, looks like it might be a
better option, as it does not modify the routing table. Still, that plugin
is now a few years old. Are there any known interoperability issues with
dyn-gw ping parameter and the SmartGateway plugin?

[Teco Boot]

I use both dyn_gw and sgw. The sgw HNA advertisement is controlled by dyn_gw, this works well.

I tested the dyn_gw ping, but I don't use it today because I don't want the overhead or delay for bi-dir check or dependency on pinged host. But yes, false default route advertisements have bad effects.

During dyn_gw rework some years ago, Henning asked to remove the separate thread for the ping. Caspar only checked / changed the code so the thread is only set up if ping was configured. I don't know why Henning was concerned.

Options for improvement: use layer-2 or data plane feedback and adjust the HNA saw metrics? And / or only ping if there is no user traffic? Maybe use something stupid simple like ntp status. If clock is not in sync, half the data rate...
For dynamic metrics, multi sgw is almost mandatory to use best exit path for new connections.

Teco

Post by Ben West
Hello again,
https://github.com/opentechinstitute/olsrd/blob/release-0.6.5.4/lib/dyn_gw/README_DYN_GW
http://luci.subsignal.org/trac/browser/luci/trunk/contrib/package/freifunk-gwcheck
I had been trying out freifunk-gwcheck with its default config on nodes running olsrd v0.6.5.4 and with SmartGateway enabled. However, I was finding gateway nodes occasionally losing their default route entirely after outages in their upstream Internet connection. That is, freifunk-gwcheck would detect the outage and modify node's local routing table, but it would apparently not recover when the outage was resolved. I'm not asking on this list for any further into about freifunk-gwcheck operation, as this is not the right venue.
The ping parameter for the dyn-gw plugin, however, looks like it might be a better option, as it does not modify the routing table. Still, that plugin is now a few years old. Are there any known interoperability issues with dyn-gw ping parameter and the SmartGateway plugin?
--
Ben West
http://gowasabi.net
314-246-9434
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