Proactive sending Status-Server requests

[d1sl1ke]

Message

Hello!
I haven't found way to open a feature req and haven't found this behaviour in doc..
Is possible to add proactive sending "Status-Servers" to each home server from a pool which described in proxy.conf when:

• proxy server has just been started (current status of home server is "Idle");
• after "idle_timeout" without any requests from client that could be proxied ("idle_timeout" could be conifgured parameter in home server, pool or relam section).

I think this feature is must have for high availability clsuter and system would not loose time to detect home server failure.
Requested algo for load-balance type:

1. first start (dont detect any processed requests)
2. wait for idle_timeout
3. start sending status-server requests
4. mark the server 'Alive' or 'zombie' (depends on behavior of home server)

Thank you for fast reply!

[d1sl1ke]

My bad.. missclick to close.. :(

[alandekok]

Doing this at the start is useful, but isn't enough. The only way to tell if a server is alive is to send it packets. For a number of reasons, sending Status-Server all of the time isn't useful. For details, see:

https://datatracker.ietf.org/doc/html/rfc2865#section-2.6

i.e. if you're not sending real packets, you don't care if it's up or down. If you are sending real packets, then those packets will tell you if the server is up or down.

And even if you're sending Status-Server, the home server could go down in the 5 seconds between one Status-Server and the next. So you still have to rely on real packets to determine if the server is down.

The only reason to continually send Status-Server is to have the server fail-over before sending real packets to it. But even that is very much a corner case.

i.e. if the next server is down for extended periods of time, the solution is to fix it so that it doesn't go down.

The underlying issue is that RADIUS does not have a routing protocol. There is no way for a server to tell a client "I'm up". Which means that any use of Status-Server is a hack which might help in some situations, but also causes problems in other situations.

[d1sl1ke]

I mean sending Status-Server if proxy doesn't have any real requests.
And it's actual behavior for the new implementation or after equipment repair: before moving the production traffic proxy would detect Alive servers only.

[alandekok]

Yes.... please read my comment again. That's exactly what I was saying. I explained that it had issues, and what those issues are.

[d1sl1ke]

Hello!
Sorry for late reply. I found workaround in freeradius-4.0~alpha1-1.el8.src.rpm from http://www.freeradius.org/

I have configured parallel proxying the Auth-Req from NAS to check status server (the simillar behavior like using "Access-Request" type to check status of home server).

Do you have info about roadmap to release version4 (if you have)? Thank you