[gentoo-user] OT: wlan0 is sssloooow

[Sergio Polini <sp_rm_it@yahoo.it>]

Scenario:
- I have a HAG (Home Access Gateway, which embodies an ADSL modem) 
installed by my provider;
- the HAG has three RJ45 ports; when a PC is connected to one of 
theese ports, it gets an IP address via DHCP;
- I have connected a Belkin wireless rooter to one of theese ports;
- I connect my PC to another port, and/or to the wireless router (by 
running modprobe ndiswrapper; then /etc/init.d/net.wlan0 is ran by 
ifplugs - at least, this is what I can guess ;-).

When I run Windows, my wireless connection is "normal", but when I run 
Gentoo there are strange delays. For example, a simple ping is fast 
under Windows, very slow under Gentoo. I have to stop net.wlan0 to 
get "normal" pings again.

As far as I can understand, it is a matter of metric.
When I only connect my PC to the wireless router, I can see:

a) under Windows (the output is in Italian, but I'm sure you can read 
it - using a fixed font may help ;-):

> route PRINT
============================================================
Elenco interfacce
0x1 ........................... MS TCP Loopback interface
0x2 ...00 16 d3 09 2d 17 ...... NVIDIA nForce Networking
0x3 ...00 14 a5 e1 d2 b9 ...... WLAN Broadcom 802.11a/b/g
============================================================
============================================================
Route attive:
Indirizzo rete           Mask     Gateway   Interfac. Metric
        0.0.0.0         0.0.0.0 192.168.2.1 192.168.2.2 25
      127.0.0.0       255.0.0.0   127.0.0.1   127.0.0.1  1
    192.168.2.0   255.255.255.0 192.168.2.2 192.168.2.2 25
    192.168.2.2 255.255.255.255   127.0.0.1   127.0.0.1 25
  192.168.2.255 255.255.255.255 192.168.2.2 192.168.2.2 25
      224.0.0.0       240.0.0.0 192.168.2.2 192.168.2.2 25
255.255.255.255 255.255.255.255 192.168.2.2           2  1
255.255.255.255 255.255.255.255 192.168.2.2 192.168.2.2  1
Gateway predefinito:       192.168.2.1
============================================================
Route permanenti:
  Nessuno

b) under Gentoo:

b.1) fast:

sergio ~ # route -n
Kernel IP routing table
Destination Gateway     Genmask       Flags Metric Ref Use Iface
192.168.2.0 0.0.0.0     255.255.255.0 U     2000   0     0 wlan0
127.0.0.0   0.0.0.0     255.0.0.0     U     0      0     0 lo
0.0.0.0     192.168.2.1 0.0.0.0       UG    2000   0     0 wlan0

b.1) very slow:

sergio ~ # route
Kernel IP routing table
Destination Gateway     Genmask       Flags Metric Ref Use Iface
192.168.2.0 *           255.255.255.0 U     2000   0     0 wlan0
loopback    *           255.0.0.0     U     0      0     0 lo
default     192.168.2.1 0.0.0.0       UG    2000   0     0 wlan0

I can just notice an astonishing difference between metrics: 25 under 
Windows, 2000 (!) under Linux.

I've tried "route del default" and then "route add default gw 
192.168.2.1 metric 0", but the wireless connection was still slow.
"Slow" means, for example, that if I use my browser and go 
to "www.google.com", "Looking for www.google.com" lasts too mach.

Any hints?
Thanks
Sergio
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