[Chilli] inconsistency in downlink and uplink bandwidths using coovachilli

[Steffen Dettmer]

Hi,

I had a similar issue which may or may not be related.
If client sends fragments, they are also dropped by Coova Chilli, I patched this out of "my" version and asked why Coova drops fragments, but did not get any answer.

Does anyone know why Coova drops IP fragments?

Steffen

-----Ursprüngliche Nachricht-----
Von: chilli-bounces at coova.org [mailto:chilli-bounces at coova.org] Im Auftrag von Michele Bergonzoni
Gesendet: Donnerstag, 15. Mai 2014 10:20
An: chilli at coova.org
Betreff: Re: [Chilli] inconsistency in downlink and uplink bandwidths using coovachilli

> we are only seeing downlink and uplink bandwidth of ~8Mbps (measured 
> using www.speedtest.net),when we have configured coovachilli to 
> 100Mbps

I had a simlar issue, it turned out to be quite weird but, I think, not uncommon. Your issue could be related or not, but it is very quick to check if you have the same problem I had.

With tcpdump on the dhcp interface, check if you see ICMP unreachables, with remote servers as source, of the "Fragmentation needed and DF set" 
kind.

If you see this messages, you will probably also see huge TCP segments being received on the same interface: in this case your NIC hardware is glueing TCP segments to offload your CPU, but chilli does not understand this.

If this is the problem, you can solve it by disabling "coalesce" or whatever it is called, in your NIC with ethtool or similar.

Regards,
			Bergonz

--
Ing. Michele Bergonzoni - Laboratori Guglielmo Marconi S.p.a.
Phone:+39-051-6781926 e-mail: bergonz at labs.it alt.advanced.networks.design.configure.operate
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