# many receive errors on Realtek 8139

## javeree

This is my card: lspci -v 

 *Quote:*   

> 
> 
> 01:07.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ (rev 10)
> 
>         Subsystem: U.S. Robotics Device 00ff
> ...

 

The relevant messages in dmesg are

 *Quote:*   

> eth1: RealTek RTL8139 at 0xce812000, 00:c0:49:d5:a2:89, IRQ 17
> 
> eth1:  Identified 8139 chip type 'RTL-8100B/8139D'
> 
> eth1: Media type forced to Full Duplex.

 

when I use the network to download any significant amount of data, I get unacceptably low transfer rates (transferring 3Mb takes more than  a minute)

When I look at ifconfig, I see

 *Quote:*   

> eth1      Link encap:Ethernet  HWaddr 00:c0:49:d5:a2:89  
> 
>           inet addr:192.168.1.53  Bcast:192.168.1.255  Mask:255.255.255.0
> 
>           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
> ...

 

Remark the RX  errors. 

I only seem to find a lot of people complaining about this card, and I most probably will be one of these soon. I just wonder if there is some way to further investigate this problem and hopefully find a solutionthat does not involve replacing the card with a new one.

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## NeddySeagoon

javeree,

Is it the card, the cable, or the switch at the other end of the cable?

The only reliable way to test is by substitution

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## think4urs11

could be related to ACPI - try with that completely disabled.

You should also check why full duplex is forced.

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## cyrillic

 *javeree wrote:*   

> I just wonder if there is some way to further investigate this problem and hopefully find a solutionthat does not involve replacing the card with a new one.

 

I would probably try replacing the cable first.

That may end up being a more expensive solution because Realtek network cards tend to be very cheap.

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## javeree

Thanks for the hints.

This definitely seems to be some hardware/interworking problem.

When I have some time I will have to do some switching around with network cards, interconnecting them not over the old 100Mb Etherhub, but directly with a cross-connect cable, and then gradually take more items in the loop.

What I already definitly found out is that a major cause of my problem is a powerline bridge that is also connected to the hub.

Using different NICs I was able to reach reasonable speeds between the two PCs (however still half duplex). However when doing on one of the PCs

 *Quote:*   

> cp -rv /mnt/remotehost/folder-with thousands-of-files/* .

 

I saw files being copied one after the other (and also saw the hub complaining about collisions). 

However, as soon as I plugged additionally the powerline brick to the hub, the network traffic completely thrashed (minutes for transferring 3 Mb). Unplugging the powerline brick => 'normal' speeds again.

The funny thing is that I have no problem sending data through the hub over the powerline brick. It just seems to interfere with the other traffic. I guess I will end up with replacing this old hub with a router or switch.

However, As I have a lot of PCs with an RTL8139 (that seems to be in all old PCs from a few years back), I'll get back to experimenting with these NIC later on.

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## NeddySeagoon

javeree,

A hub sends all traffic to all ports. Its not possible to support full duplex like that.

A switch learns what IP addresses are on what ports and only routes traffic where its needed. That allows full duplex operation because you only get packets intended for you.

Exactly what is a 'powerline bridge', what does it do ?

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## javeree

I understand the difference between a hub and a switch, and how a hob creates much more noise than a switch. However, I would expect that even with a hub full duplex is possible, just as it would be possible to reach full-duplex with a crossover cable. After all, a hub with two ethernet cables plugged in does just that (simplistically): crossing over the cables.

The powerline bridge is a device that has a power connector to plug into the wall and an ethernet connector on the other side. Somewhere else in the house there is a similar device plugged in, and ethernet-over-power (which is named powerline) allows you to connect both devices transparently. The two devices act as a bridge. In the case I was describing, the second powerline brick was plugged in into the wall outlet, but not connected to a device, so there should be not traffic going over the bridge (but I am not an expert on powerline standard). Obviously, it must be doing something to affect the traffic between the other ports.

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## eccerr0r

Not that the errors are related to the hub/switch issue, but it's impossible to support full duplex on a hub when you're dealing with 3 or more computers.  That's what the switches' job is, to connect two computers together to support a direct connection.  When dealing with three machines, how would you connect them full duplex such that each machine has a one way connection to the other two machines at the same time?  What might be missing from the picture is understanding how packets get handled beyond the wire...

In any case, we're not talking token ring here, where it is possible to do something where packets simply get forwarded through if the packets aren't destined to you.  This reduces collisions.

A crossover cable is not a hub or switch.  Since you don't have a third machine to deal with, packets can be sent directly to the other machine.

So you're using power line Ethernet?  I've always wondered about those as power line noise is a severe problem for me.  Power line noise sure can cause lots of errors in your network packets.

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