Re: Bug#709616: floods the network with pause packets

Re: Bug#709616: floods the network with pause packets

[Ben Hutchings]

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On Sat, 2013-05-25 at 10:04 +0200, Stéphane Glondu wrote:
> Le 24/05/2013 18:07, Ben Hutchings a écrit :
> >> With Linux 3.8, my computer starts (after some time) flooding its
> >> network interface with pause packets, effectively freezing it and
> >> other network-dependent computers connected to the same switch.

This is still the important issue, and regardless of whether pause
frames are being handled properly it sounds like the hardware RX path
may be locking up and that causes it to generate them continuously.  I
don't know how to investigate that, so this message is going to the
e1000e developers.

> > Switches should normally be configured to generate but not respond
> > to pause frames.  I don't know how unmanaged switches are typically
> > configured.  What do ethtool (no options and 'ethtool -a' report for
> > this device?
> 
> The other frozen computers are connected via an unmanaged switch.
> 
> # ethtool eth0
> Settings for eth0:
>         Supported ports: [ TP ]
>         Supported link modes:   10baseT/Half 10baseT/Full
>                                 100baseT/Half 100baseT/Full
>                                 1000baseT/Full
>         Supported pause frame use: No
>         Supports auto-negotiation: Yes
>         Advertised link modes:  10baseT/Half 10baseT/Full
>                                 100baseT/Half 100baseT/Full
>                                 1000baseT/Full
>         Advertised pause frame use: No
>         Advertised auto-negotiation: Yes

I forgot, e1000e still doesn't report autoneg state completely through
ethtool.  How about 'mii-tool -v eth0'?

>         Speed: 100Mb/s
>         Duplex: Full
>         Port: Twisted Pair
>         PHYAD: 2
>         Transceiver: internal
>         Auto-negotiation: on
>         MDI-X: off
>         Supports Wake-on: pumbg
>         Wake-on: g
>         Current message level: 0x00000001 (1)
>                                drv
>         Link detected: yes
> # ethtool -a eth0
> Pause parameters for eth0:
> Autonegotiate:  on
> RX:             on
> TX:             on
> 
> >> When I connect directly my laptop to the computer, and run tcpdump on
> >> the laptop, I see:
> >> [...]
> > There seems to be a bug in your laptop's network driver, because pause
> > frames should not be passed to the kernel.  (Usually they are
> > discarded by the MAC.)
> 
> Even in promiscuous mode?
[...]

MAC control frames, which include pause frames, should never be passed
to the host (specified in IEEE 802.3 clause 31.3).  In case the hardware
still delivers them to the host, it's the driver's responsibility to
discard them.  This is the same as for frames that have an error at the
Ethernet level, e.g. bad CRC.

Ben.

-- 
Ben Hutchings
Computers are not intelligent.	They only think they are.

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Bug#709616: floods the network with pause packets

[Stéphane Glondu]

Le 26/05/2013 03:54, Ben Hutchings a écrit :
> I forgot, e1000e still doesn't report autoneg state completely through
> ethtool.  How about 'mii-tool -v eth0'?

# mii-tool -v eth0
SIOCGMIIREG on eth0 failed: Input/output error
SIOCGMIIREG on eth0 failed: Input/output error
eth0: negotiated 100baseTx-FD flow-control, link ok
  product info: vendor 00:55:00, model 9 rev 0
  basic mode:   autonegotiation enabled
  basic status: autonegotiation complete, link ok
  capabilities: 1000baseT-FD 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD
  advertising:  100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD flow-control
  link partner: 1000baseT-FD 100baseTx-FD 100baseTx-HD 10baseT-FD
10baseT-HD flow-control


I am not sure about who to put in CC of this mail; I've just put the
Debian bug.


Cheers,

-- 
Stéphane

Re: Bug#709616: floods the network with pause packets

[Ben Hutchings]

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On Sun, 2013-05-26 at 11:02 +0200, Stéphane Glondu wrote:
> Le 26/05/2013 03:54, Ben Hutchings a écrit :
> > I forgot, e1000e still doesn't report autoneg state completely through
> > ethtool.  How about 'mii-tool -v eth0'?
> 
> # mii-tool -v eth0
> SIOCGMIIREG on eth0 failed: Input/output error
> SIOCGMIIREG on eth0 failed: Input/output error
> eth0: negotiated 100baseTx-FD flow-control, link ok
>   product info: vendor 00:55:00, model 9 rev 0
>   basic mode:   autonegotiation enabled
>   basic status: autonegotiation complete, link ok
>   capabilities: 1000baseT-FD 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD
>   advertising:  100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD flow-control
>   link partner: 1000baseT-FD 100baseTx-FD 100baseTx-HD 10baseT-FD
> 10baseT-HD flow-control

OK, so the switch is indeed defective: it says it can handle pause
frames, but it can't.

Could you check whether the switch is also sending pause frames back to
the port that's generating them?

> I am not sure about who to put in CC of this mail; I've just put the
> Debian bug.

You replied-to-all, which is correct.

Ben.

-- 
Ben Hutchings
Computers are not intelligent.	They only think they are.

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Bug#709616: floods the network with pause packets

[Stéphane Glondu]

Le 26/05/2013 18:10, Ben Hutchings a écrit :
> OK, so the switch is indeed defective: it says it can handle pause
> frames, but it can't.

The problem happened on (at least) two different switches from different
manufacturers (Transtec and Netgear).

FWIW, the problem just happened on another machine (with same hardware)
this morning. It is running Ubuntu with kernel 3.5.0-31-generic.

> Could you check whether the switch is also sending pause frames back to
> the port that's generating them?

How exactly do I do that? Is disconnecting the faulty computer and
connecting my laptop in its place right?


Cheers,

-- 
Stéphane


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Re: Bug#709616: floods the network with pause packets

[Ben Hutchings]

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On Thu, 2013-05-30 at 11:21 +0200, Stéphane Glondu wrote:
> Le 26/05/2013 18:10, Ben Hutchings a écrit :
> > OK, so the switch is indeed defective: it says it can handle pause
> > frames, but it can't.
> 
> The problem happened on (at least) two different switches from different
> manufacturers (Transtec and Netgear).
> 
> FWIW, the problem just happened on another machine (with same hardware)
> this morning. It is running Ubuntu with kernel 3.5.0-31-generic.
> 
> > Could you check whether the switch is also sending pause frames back to
> > the port that's generating them?
> 
> How exactly do I do that? Is disconnecting the faulty computer and
> connecting my laptop in its place right?

ethtool -S eth0 | grep flow_control

Ben.

-- 
Ben Hutchings
If at first you don't succeed, you're doing about average.

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Re: Bug#709616: floods the network with pause packets

[Stéphane Glondu]

Le 30/05/2013 14:58, Ben Hutchings a écrit :
>>> Could you check whether the switch is also sending pause frames back to
>>> the port that's generating them?
>>
>> How exactly do I do that? Is disconnecting the faulty computer and
>> connecting my laptop in its place right?
> 
> ethtool -S eth0 | grep flow_control

     rx_flow_control_xon: 318
     rx_flow_control_xoff: 318
     tx_flow_control_xon: 0
     tx_flow_control_xoff: 0

-- 
Stéphane