RX Packet errors on ADSL line

RX Packet errors on ADSL line

Post by Fernando Garcia Penel » Sat, 06 Oct 2001 09:33:47



I recently installed RH 7.1 and managed to make a connection with my
ADSL provider through Roaring Penguin. I share the internet connection
with a Windows Me box with IP masquerading. Recently however I've
experienced performance problems on the ADSL line, and when running
ifconfig I noticed many errors on the IP packets. Being a newcomer to
the Linux world, I think it has to do with config problems, but I
would like any input on what could be wrong. This is a sample output
on ifconfig:

eth0      Link encap:Ethernet  HWaddr 00:01:03:32:02:BB  
          inet addr:192.168.0.1  Bcast:192.168.0.255
Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:260704 errors:0 dropped:0 overruns:0 frame:0
          TX packets:259897 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100
          Interrupt:9 Base address:0xe000

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:50 errors:0 dropped:0 overruns:0 frame:0
          TX packets:50 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0

ppp0      Link encap:Point-to-Point Protocol  
          inet addr:200.63.139.49  P-t-P:192.168.96.237
Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1492  Metric:1
          RX packets:124291 errors:126938 dropped:0 overruns:0 frame:0
          TX packets:132088 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:3

Thanks in advance.

 
 
 

RX Packet errors on ADSL line

Post by Simon Gree » Sat, 06 Oct 2001 09:38:40


Try reducing the MTU for your PPP device. I believe that 1412 or
thereabouts is the recommended maximum due to the fact that PPP has to
add it's own headers onto the IP packet. When the MTU is too high all
this doesn't fit into a single ether packet (1500 bytes including
ethernet headers) and you will have problems.

Cheers
Simon


>I recently installed RH 7.1 and managed to make a connection with my
>ADSL provider through Roaring Penguin. I share the internet connection
>with a Windows Me box with IP masquerading. Recently however I've
>experienced performance problems on the ADSL line, and when running
>ifconfig I noticed many errors on the IP packets. Being a newcomer to
>the Linux world, I think it has to do with config problems, but I
>would like any input on what could be wrong. This is a sample output
>on ifconfig:

>eth0      Link encap:Ethernet  HWaddr 00:01:03:32:02:BB  
>          inet addr:192.168.0.1  Bcast:192.168.0.255
>Mask:255.255.255.0
>          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
>          RX packets:260704 errors:0 dropped:0 overruns:0 frame:0
>          TX packets:259897 errors:0 dropped:0 overruns:0 carrier:0
>          collisions:0 txqueuelen:100
>          Interrupt:9 Base address:0xe000

>lo        Link encap:Local Loopback  
>          inet addr:127.0.0.1  Mask:255.0.0.0
>          UP LOOPBACK RUNNING  MTU:16436  Metric:1
>          RX packets:50 errors:0 dropped:0 overruns:0 frame:0
>          TX packets:50 errors:0 dropped:0 overruns:0 carrier:0
>          collisions:0 txqueuelen:0

>ppp0      Link encap:Point-to-Point Protocol  
>          inet addr:200.63.139.49  P-t-P:192.168.96.237
>Mask:255.255.255.255
>          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1492  Metric:1
>          RX packets:124291 errors:126938 dropped:0 overruns:0 frame:0
>          TX packets:132088 errors:0 dropped:0 overruns:0 carrier:0
>          collisions:0 txqueuelen:3

>Thanks in advance.

--
Simon Green
Logica Mobile Networks
+61 419 479 908

Please read the lawyer-speak below, it costs us 50 quid a word!

Plain ASCII: Virus-free since 1963!

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RX Packet errors on ADSL line

Post by Fernando Garcia Penel » Sat, 06 Oct 2001 23:17:23


Thanks for the tip. Reducing mtu to 1412 made it work like a charm.

> Try reducing the MTU for your PPP device. I believe that 1412 or
> thereabouts is the recommended maximum due to the fact that PPP has to
> add it's own headers onto the IP packet. When the MTU is too high all
> this doesn't fit into a single ether packet (1500 bytes including
> ethernet headers) and you will have problems.

> Cheers
> Simon


> >I recently installed RH 7.1 and managed to make a connection with my
> >ADSL provider through Roaring Penguin. I share the internet connection
> >with a Windows Me box with IP masquerading. Recently however I've
> >experienced performance problems on the ADSL line, and when running
> >ifconfig I noticed many errors on the IP packets. Being a newcomer to
> >the Linux world, I think it has to do with config problems, but I
> >would like any input on what could be wrong. This is a sample output
> >on ifconfig:

> >eth0      Link encap:Ethernet  HWaddr 00:01:03:32:02:BB  
> >          inet addr:192.168.0.1  Bcast:192.168.0.255
> >Mask:255.255.255.0
> >          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
> >          RX packets:260704 errors:0 dropped:0 overruns:0 frame:0
> >          TX packets:259897 errors:0 dropped:0 overruns:0 carrier:0
> >          collisions:0 txqueuelen:100
> >          Interrupt:9 Base address:0xe000

> >lo        Link encap:Local Loopback  
> >          inet addr:127.0.0.1  Mask:255.0.0.0
> >          UP LOOPBACK RUNNING  MTU:16436  Metric:1
> >          RX packets:50 errors:0 dropped:0 overruns:0 frame:0
> >          TX packets:50 errors:0 dropped:0 overruns:0 carrier:0
> >          collisions:0 txqueuelen:0

> >ppp0      Link encap:Point-to-Point Protocol  
> >          inet addr:200.63.139.49  P-t-P:192.168.96.237
> >Mask:255.255.255.255
> >          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1492  Metric:1
> >          RX packets:124291 errors:126938 dropped:0 overruns:0 frame:0
> >          TX packets:132088 errors:0 dropped:0 overruns:0 carrier:0
> >          collisions:0 txqueuelen:3

> >Thanks in advance.

> --
> Simon Green
> Logica Mobile Networks
> +61 419 479 908

> Please read the lawyer-speak below, it costs us 50 quid a word!

> Plain ASCII: Virus-free since 1963!

 
 
 

1. 3c905 100Mbps: RX-ERR RX-DRP RX-OVR?

Hi,

I have really strange effects using the 3c905 with the new 3c59x.c driver.

http://cesdis.gsfc.nasa.gov/linux/drivers/3c59x.c
line 725: vp->full_bus_master_tx = 0;
The cards didn't work at all without this patch.
At boot time, the Pacing bug is detected so busmastering isn't enabled.

I am administrating an 100Mbps net with several Dual PPro 200MHz (2.0.30)
and some SGI O2. At first, the only problem was that a copy O2->PPro caused
many RX-OVR on the PPro and bad performance (250KBps), while the other
direction worked fine (5,6MBps).

Then I tested the tcp connection between the PPros (with ttcp). Some
connections worked fine (5,6MBps), others also caused some RX-OVR (visible
by 'netstat -i') and bad performance (in this case: 2,5MBps). The strange
thing is that all the PPros are equally equipped (hardware and software).

I tried a lot of things (reconfigured the kernel of the O2 with small buffers
etc, changed some of the network options on the PPro, eg. 'optimize as router
not host', 'PC/TCP compatibility mode', 'Disable Path MTU Discovery', disabled
'Allow large windows') but nothing changed this effect.

The only workaround by now is to reduce the rsize and wsize of mounts (O2->PPro
is 2560 now). But this doesn't effect ftp transfers.

What is responsible for these strange RX-ERR RX-DRP RX-OVR effects? Is there
still a bug in the 3c900.c:v0.40 4/16/97 driver?

Thanks for any hint.
T.B.

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