howto/Bird2.md
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@@ -429,15 +429,14 @@ protocol rpki rpki_dn42{
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}
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```
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### Use BFD in bird2
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-Warning: Enabling BFD may cause slow BGP flapping, use it with caution.
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-
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BFD is an additional protocol with extremely low overhead to detect failures in the switching plane between peers,
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-it is used widely by cleanet peerings and some networks already have enabled it globally.
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+it is used widely by cleanet peerings and some networks in DN42 already have enabled it globally.
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To do a basic configuration you need to add 1 line to your bird.conf and enable it per peer or globally by defining it in the
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template.
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It is currently recommended that you only enable it for each peer that supports it and has it enabled.
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-Add this above the template for dnpeers.
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It acts as a detection mechanism that is very fast and can detect for example if your tunnel link is down.
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+
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+Add this above the template for dnpeers.
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```conf
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protocol bfd {};
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```
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@@ -457,4 +456,11 @@ protocol bgp <NEIGHBOR_NAME> from dnpeers {
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};
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};
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```
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+
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+**Warning:** with high frequency connectivity issues and/or/with ping over ~150ms and/or/with significant packet loss
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+it can cause significant issues with route flapping since BFD uses UDP packets to reduce overhead.
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+It should not be used in extremely long distance peers with the default settings and use of it on
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+lossy networks like but not only, Satellite, Wireless Mesh Networks should be avoided.
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+Regardless, use of BFD in high quality fiber based networks with low ping is optimal.
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+
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Additional documentation about the BFD protocol is available at [the BIRD2 documentation](https://bird.network.cz/?get_doc&v=20&f=bird-6.html#ss6.3) .
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