will frequently changing allowed-list result in latency spikes?

Arvid Picciani aep at exys.org
Wed Apr 20 08:05:30 UTC 2022


we're currently using wg as point-to-point transport between thousands of vms.
each peer has a separate interface so we can do BGP with bird.

this works extremely well. But due to lack of port-reuse, eventually
you run out of udp ports.
Now i'm thinking of redesigning it with a single wg interface and
using wgs native destination selection which is based on allow-list.

that means every topology change results in a netlink call to wg to
replace all affected peers with a new peer with a new allowed-list.

In a quick test i couldn't see any problems with that.  But i'm
worried that might change with scale. Replacing a peer config might
flush its buffer, possibly resulting in packet loss.  Or more likely
reset its crypto session, resulting in a latency spike until the
handshake finished.

anyone has more insight into that?


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