L2TP capacity Tunnels/Sessions

What is the capacity of LT2P sessions on a VYOS router acting as the LNS?

All limits are based on your hardware CPU/NICs/Memory etc.

with 64GB and 4 CPU how many sessions?
looking to terminate a lot of sessions with low bandwidth per session.

Thank you , what hardware specs would I neet to support 5000 sessions ?

Depends on what kind of performance you expect in total vs single session.

Memory wise unless you run BGP and import large routingtables through peers etc 512MB of RAM is sufficient to boot VyOS 1.5-rolling.

Mine (in the lab) utilizes about 475MB after boot (thats including memory buffers/caching).

For conntrack its often said to estimate 320bytes per session so 5000 concurrent sessions would need approx 1.5 MB of RAM.

And then we need tcp send/receive buffers. Lets assume maxsize without timestamping which is 64Kbyte per direction so 128Kbyte per session which with 5000 concurrent sessions would mean about 625 MB of RAM.

So give or take 475 + 1.5 + 625 = 1101.5 MB of RAM. Lets round that up to at least 2GB of RAM for your VyOS and then whatever CPU you can afford (along with proper NICs that supports various offloading).

Over at OPNsense shop you can see various estimates (thats with OPNsense currently FreeBSD 13.2 but still while VyOS 1.5-rolling is currently using Linux LTS kernel 6.1.55)):



among other models…

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