[Oisf-users] Percentage of dropped packets

[Chris Wakelin]

On 30/05/12 10:39, Peter Bates wrote:
> 
> Hello again all
> 
> Adding a point to my own reply...
> 
> On 30/05/2012 09:29, Peter Bates wrote:
>> When I first had the 10Gb NIC up I was seeing (in ifconfig) rx 
>> dropped increasing and no rx packets received - and subsequently 
>> nothing to capture in tcpdump/etc - however as the advice above 
>> changes all the settings to 'off' I was unsure which one
>> actually solved my problem.
> 
> My ixgbe settings are now: Offload parameters for eth6: 
> rx-checksumming: on tx-checksumming: on scatter-gather: on 
> tcp-segmentation-offload: on udp-fragmentation-offload: off 
> generic-segmentation-offload: on generic-receive-offload: on 
> large-receive-offload: off rx-vlan-offload: off tx-vlan-offload:
> off ntuple-filters: off receive-hashing: off
> 
> ... I find when I turn 'large-receive-offload' on then my NIC
> stops receiving packets and drops everything.
> 
> I'm receiving traffic from a Cisco SPAN not sure whether it 
> encapsulates the packets or makes them larger than 1514 hence this 
> setting disturbing the capture.

It might be worth trying a higher MTU, say "ifconfig eth6 mtu 1522".
Are there VLAN tags on the port? Our Extreme border switches add VLAN
tags to the port mirror in one direction only :-o

It might also be worth compiling your own ixgbe driver from
http://sourceforge.net/projects/e1000/files/ixgbe%20stable/ or with
PF_RING as the one shipped in the 2.6.x kernels seems very old.

I'm using PF_RING-enabled ixgbe-3.7.17 (DNA version at the moment) and
have left the offload parameters at the defaults:

Offload parameters for dna0:
rx-checksumming: on
tx-checksumming: on
scatter-gather: on
tcp-segmentation-offload: on
udp-fragmentation-offload: off
generic-segmentation-offload: on
generic-receive-offload: on
large-receive-offload: on
rx-vlan-offload: off
tx-vlan-offload: off
ntuple-filters: off
receive-hashing: off


driver: ixgbe
version: 3.7.17-DNA
firmware-version: 0x18f60001
bus-info: 0000:0c:00.0
supports-statistics: yes
supports-test: yes
supports-eeprom-access: yes
supports-register-dump: yes
supports-priv-flags: no

Best Wishes,
Chris

-- 
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Christopher Wakelin,                           c.d.wakelin at reading.ac.uk
IT Services Centre, The University of Reading,  Tel: +44 (0)118 378 2908
Whiteknights, Reading, RG6 6AF, UK              Fax: +44 (0)118 975 3094