Re: [Cerowrt-devel] Build instructions for regular OpenWRT with Ceropackages

[Mikael Abrahamsson <swmike@swm.pp.se>]

On Wed, 1 Jul 2015, David Lang wrote:

> not true, the switch doesn't give any way for traffic to get from one vlan to 
> the other one, so if you have gig-e connections on both sides, the traffic 
> going from one to the other will have to go through the soc, so if there is 
> more than 1Gb of traffic in either direction the interface will be saturated.

I don't see how it can be. The switch has a 4 externally facing ports, 
these all go to a single SoC port that is GigE, so the SoC cannot ingest 
more than 1G of traffic from the 4 LAN ports. The L2 switch chip will do 
the egress dropping from LAN ports->SoC ports, so there is no AQM there.

> The problem is if you have a slower connection, the bottleneck is in the 
> switch not the soc. you may be able to set the soc-switch interface to 100Mb 
> (make sure you have access through another interface in case you cut yourself 
> off) and that would make the soc see the queue directly.

That is my point. There is no way by doing traffic LAN<->WAN to get egress 
congestion on the SoC ports, and it's on the SOC ports we can do AQM.

The SoC ports is gigabit ethernet only, no 10/100 available according to 
ethtool.

So the only way to generate congestion egress on the WAN SOC port is to 
add traffic locally from the SoC (iperf3 for instance), or adding traffic 
from Wifi.

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