[ixpmanager] sFLOW graph limiting

[Nick Hilliard]

Paul Emmons via ixpmanager wrote on 27/04/2022 22:07:
> The downside was that our sflow rrds got hosed.   Any thoughts of being 
> able to enforce an upper limit in the RRDs?

this is not as simple as it looks.  Once you hard-code a limit into an 
RRD, it's difficult to change later because it needs to be done using 
"rrdtool tune --maximum"; this is problematic because you then need a 
second process outside the sflow-to-rrd script which handles 
provisioning changes. And then, which value do you set the max to - the 
ingress flow or the egress?  What if there's 100g ingress and 1G egress? 
What's the correct semantic value to use here?  One organisation will 
want to see the size of their DDOS; the other the utilisation on their 
link.  I.e. if you want fabric utilisation and congestion info, you 
would need to set all graphs on the IXP to be the size of the largest 
link on the entire IXP.

Nick