[Bloat] [Babel-users] RTT stability inside a GRE tunnel

[Mikael Abrahamsson]

On Tue, 2 Jul 2013, Juliusz Chroboczek wrote:

> Anybody seen anything similar?

I don't know if this is the cause, but older gear from Extreme Networks 
(their end-of-90ties and beginning of 2000s), will do ICMP in slow-path 
when routing (even packets going through the device) and "everything else" 
in fast-path. This could cause latency spikes and PDV approximately 
similar to what's seen in the picture.

The seen behaviour could also perhaps be caused by per-packet QoS settings 
in the path, where ICMP might have lower priority than GRE. I don't think 
this explanation is likely though.

-- 
Mikael Abrahamsson    email: swmike at swm.pp.se